AN-861 APPLICATION NOTE
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AN-861 APPLICATION NOTE One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com ADP1653 Evaluation and Test Methods by Leo Chou and Adrian Fox GENERAL DESCRIPTION This application note presents some methods used in evaluating the ADP1653 white LED driver. The ADP1653 evaluation board, sold by Analog Devices, Inc., is used during the evaluation, but users may choose to design their own evaluation boards. For simplicity, however, all the testing procedures in this application note are based on the Analog Devices ADP1653 evaluation board. There are also switches on the board that allow users to easily change voltages at certain pins. Note, however, that even though this application note is based on the ADP1653 evaluation board, it is not a user manual that shows how to use the board and the included software. For more details, see the document ADP1653 Flash LED Driver Evaluation Board Manual. The ADP1653 evaluation board is designed specifically for the purpose of evaluation. There are numerous jumpers and test points on the board for users to measure currents, voltages, or probe important nodes. U3 C30 MINI USB C51 C8 C11 C15 C16 5V VIC J6 R66 REV 0.4.1 D7 R23 GP1 GND GP2 SDA Tx R6 R5 J4 R4 R3 SETI R2 ANALOG DEVICES C1 GND J1 SETF L1 SCL R25 OUT D1 D2 C3 SHARP R1 C2 J3 J2 D3 JP3 GND GND D10 HPLED U4 JP11 JP10 VBAT 1.8V 3.3V H ADI USB/I2C INTERFACE 0.4 J8 J5 SDA R65 VIC VBAT SETT INT R64 C17 C14 R22 R24 C19 EN J7 STR U2 C10 JP12 5V C6 VBAT GND VBAT GND GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 R51 R31 C21 L SCL/CTRL1 H JP9 L L H SDA/CTRL0 TxMASK ADP1653 Figure 1. Rev. 0 | Page 1 of 20 06320-001 C31 L JP6 GP1 GP2 D6 R20 R27 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR FUNCTIONAL BLOCK DIAGRAM AN-861 TABLE OF CONTENTS General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Board Schematics.............................................................................. 3 Motherboard ................................................................................. 3 Daughter Board ............................................................................ 4 General Considerations ................................................................... 5 Cables ............................................................................................. 5 Ammeter........................................................................................ 5 Temperature Measurement ......................................................... 5 Evaluation Methods ......................................................................... 6 Shutdown Current........................................................................ 6 VDD Soft Power-Down Current................................................... 7 VDD Operating Current HPLED Register = 001 (Boost Not Running, One LED) ......................................................................9 VDD Operating Current HPLED Register = 001 (Boost Running, Two LEDs) ................................................................. 10 Undervoltage Lockout Threshold (UVLO) ............................ 11 OUT Overvoltage Threshold.................................................... 12 LX Switching Frequency............................................................ 13 OUT Soft Start Ramp ................................................................ 14 Start-Up Inrush Current............................................................ 15 Efficiency..................................................................................... 16 Current Limit .............................................................................. 18 Line Regulation........................................................................... 19 VDD Operating Current ILED Register = 001 ........................... 8 Rev. 0 | Page 2 of 20 VDD D– D+ ID GND SHELL C31 47µF TP16 3.3V C30 100nF TP18 IC_VDD TP19 VBAT TP17 USB OUT1 IN1 TP20 1.8V ADP3303- 3.3 OUT2 NR GND IN2 ERR SD U3 ADP1715-1.8 C17 C18 C14 C15 C16 1nF 100nF 100nF 100nF 100nF 1 2 3 4 5 6 R27 100kΩ GND1 TP21 GND 1 2 3 IC_VDD VBAT_M IC_VDD2 2 1 3 C12 1µF 5V USB JP13 C5 100nF R31 1kΩ Y1 2 3 1 2 3 C19 100nF R22 10kΩ RES IFCLK GND1 SDA JP11 TP15 1 1 2 3 3 R33* 105kΩ STR SDA/CTRL0 2 SDA1 INT GPIO2 GPIO1 3.3V JP10 1 1 3.3V PAD 29 30 31 32 33 34 35 36 37 38 39 40 41 42 2 SCL/CTRL1 2 3 3 1 C6 100nF R30 100kΩ JP9 IC_VDD GPIO1 GPIO2 SDA1 SCL1 INT STR EN 2 1 EN 3 JP6 1 1 1 2 3 R66* R65* R64* R63* R62* 2 SETF 2 3 R35* 0Ω IC_VDD 3 IC_VDD ENABLE JP8 4 19 17 15 13 11 9 7 5 3 1 JP20 1 2 3 4 5 6 7 8 9 10 6 JP21 1 2 3 4 5 6 7 8 9 10 8 HEADER 10 1 2 3 4 5 6 7 8 9 10 R51* 7 VBAT_M JP7 HEADER LARGE 8 R23* D7* LED 2 HEADERS USED FOR MECHANICAL STABILITY 1 ON MOTHER, DAUGHTER HEADER 10 1 2 3 4 5 6 7 8 9 10 5 SCL1 SDA1 3 R20* D6* LED GPIO2 GPIO1 HEADER LARGE 10 × 2 20 18 16 14 12 10 8 6 4 2 STROBE ! 2 R19* 2 1 SW PUSHBUTTON S1 3 4 INT D5 LED R32 105kΩ IC_VDD STROBE ! SWITCH BRINGS STR HIGH FOR FLASH ! IC_VDD 3.3V EN R34* 105kΩ 3.3V 3.3V C7 10µF SCL1 PAD CTL0 CTL1 CTL2 VCC4 PA0/INT1 VCC1 PA1/INT1 PA2/*SLOE PA3/*WU2 AGND2 R25 2.2kΩ U4 M24C64-R CY7C68013A PA4/FIFOADR0 PA5/FIFOADR1 PA6/*PKTEND PA7/*FLAG GND4 RESET D– D+ AVCC2 AGND1 XTALIN XTALOUT AVCC1 RDY1/SLWR RDY0/SLRD R24 2.2kΩ 14 13 12 11 10 9 8 7 6 5 4 3 2 1 I2C CONTROL LINES SCL TP14 IC_VDD C11 2.2uF 3.3V C8 6.2pF C51 100nF 3.3V 1.8V 3.3V IC_VDD1 2 1 3 JP12 IC_VDD 3.3V C10 10nF C9 6.2pF CRYSTAL14 1 4 3.3V NOTES 1. DECOUPLING FOR EACH OF 6 68013A DIGITAL INPUTS, 0402 CAPS PLACED AS CLOSE AS POSSIBLE TO EACH PIN. GROUND IS COMMON GROUND TO AGND AT 1 POINT. NO GROUND DISTINCTION IN SCHEMATIC. 2. IC_VDD IS THE DIGITAL INTERFACE SUPPLY VOLTAGE—IC_VDD SHOULD BE CONNECTED TO EITHER 5V, 3.3V, 1.8V OR VBATT USING J4, J5. 3. R33, R34, R35 CAN BE ADDED IN HW MODE TO ALLOW FAST TRANSITIONS BETWEEN STATES *NOT POPULATED 3.3V C13 100nF 1.8V VBAT_M IC_VDD 5V USB 3.3V USB MINI B JP5 5V USB GND2 15 SS 56 SCL 16 OUT 55 VCC6 SDA 17 R26 220kΩ U2 18 C50 2.2µF VCC2 GND6 54 CLKOUT 53 GND5 PB0/FD0 19 D8 LED PB1/FD1 20 GND3 PB2/FD2 21 GND4 PB3/FD3 22 IN 23 EN 24 U5 PB4/FD4 3.3V PB5/FD5 52 PD7/FD14 51 PD6/FD13 50 PD5/FD12 49 PD4/FD11 48 PD3/FD10 47 PD2/FD9 PB6/FD6 25 C21 2.2µF WP VCC A0 PB7/FD7 26 1.8V SCL A1 VCC3 27 C20 2.2µF SDA Rev. 0 | Page 3 of 20 A2 Figure 2. Motherboard Schematics VSS GND2 46 PD1/FD9 45 PD0/FD8 44 *WAKEUP 43 VCC5 GND3 28 3.3V 06320-002 R21 100kΩ AN-861 BOARD SCHEMATICS MOTHERBOARD 14 13 Figure 3. Daughter Board Schematics J6 8 TxMASK 9 10 8 9 10 VBAT TP3 VIC_D 7 7 4 INT 4 6 CTRL0/SDA 3 STR 3 6 2 EN 2 5 CTRL1/SCL 1 1 5 VIC_D JP2 NOTES 1. GND (IC), PGND SHOULD BE CONNECTED AT A SINGLE POINT. *NOT POPULATED ON THE BOARD. 20 12 11 19 10 9 18 8 7 17 6 5 16 4 3 15 2 1 JP1 VBAT PGND TP10 AGND TP13 AGND TP5 R2 10kΩ VIC_D CTRL0/SDA VIC_D CTRL1/SCL R4 332kΩ VBAT VIC_D J5 TP4 R5 105kΩ VIC_D J4 R6 47kΩ J7 VBAT VBAT CTRL0/SDA R3 47kΩ J8 J1 1 2 U1 17 9 10 11 12 PGND D1 2 1 J2 TP2 C3 * HPLED D3 WHITE-LED D2 WHITE-LED JP3 OUT 4 C2 3 A2 2 A1 1 C1 D9 CAPACITOR/TVS DIODES CAN BE PLACED HERE FOR ESD PROTECTION. J3 OUT R1 0Ω 3 2 1 INTF = GND, I 2C MODE INTF 3 2 C2 4.7 µF LX NODE TP1 INTF = HI, HW MODE VBAT OUT PAD HPLED INTF INT PGND 1 L1 2.2µH C1 4.7µF POWER SECTION ADP1653 CTRL1/SCL SETF D4 INDICATOR LED 4 3 2 1 SETT ILED 6 TP11 AGND SETI 5 13 TP12 AGND 16 STR 15 EN 14 VDD OUT 7 LX GND 8 Rev. 0 | Page 4 of 20 D10 WHITE-LED SHARP LED C3 5 A3 6 A4 7 C4 8 06320-003 RANDOM AGND TESTPOINTS FOR DIGITAL SIGNALS. AN-861 DAUGHTER BOARD AN-861 GENERAL CONSIDERATIONS CABLES Because the ADP1653 is a high current, high power device, the cables used to connect the power supply to the chip must be as thick and short as possible to minimize the series resistance. However, no matter how short and thick a cable is, it still has a finite resistance, and the voltage at the VBAT pin is lower than the power supply voltage. For example, if the cable resistance is 0.1 Ω and the input current is 1 A, there is a 0.1 V drop between the power supply and the VBAT pin. That means if the supply is set to 2.8 V, the chip gets only 2.7 V, and, in some cases, this can trigger the UVLO. Users are, therefore, advised to take into account the IR drop across cables. It is recommended that the voltage be measured at VBAT with a voltmeter and the supply adjusted until the desired VBAT voltage is obtained. AMMETER Even though an ammeter is convenient to use, because of the large current levels in power devices its internal resistance could cause incorrect measurements. As a result, care must be taken when using an ammeter. Users should ensure that the scale is set to the order of magnitude of the current being used to minimize the series resistance of the ammeter. For example, when measuring a current that is expected to be on the order of hundreds of microamperes, the scale should be set to hundreds of microamperes or a few milliamperes. If the current measured is going to be high (hundreds of milliamperes or even amperes), then using an ammeter could cause a significant error. In such cases, a small, high precision power resistor should be used. A good choice is a 1%, 0.1 Ω power strip that has a rating of several amps. Then, measuring the voltage across the resistor and dividing it by the resistance gives the current reading. TEMPERATURE MEASUREMENT Because the Cypress CY7C68013A chip on the motherboard is not rated at −40°C, it is not recommended to subject the motherboard to temperature testing. As a result, a ribbon cable is provided so users can separate the motherboard and daughter board for temperature measurement. Connect both ends of the ribbon cable to the headers on the motherboard and daughter board and place only the daughter board under temperature stress. Rev. 0 | Page 5 of 20 AN-861 EVALUATION METHODS SHUTDOWN CURRENT To measure the shutdown current, connect an ammeter in series with the power supply and the VBAT pin. The ammeter should have enough resolution to measure down to tens of nanoamperes. Otherwise, it is difficult to distinguish the actual current from noise. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER C31 U3 MINI USB SHORT VIC TO 3.3V C51 C8 C11 C15 C16 5V VIC J6 R66 D7 R23 D6 R20 GP1 GND GP2 SDA Tx R6 R5 J4 R4 R3 SETI REV 0.4.1 R2 SHORT THIS JUMPER GND J1 OUT D1 D2 SHARP R1 C2 J3 C3 J2 D3 JP3 GND GND D10 HPLED U4 JP11 JP10 H NOTES 1. USE THICK, SHORT CABLES. SCL ANALOG DEVICES C1 SETF L1 J5 R25 VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 J8 INT SDA R65 VIC VBAT SETT J7 STR R64 C17 C14 R22 R24 C19 EN U2 C10 JP12 5V C6 VBAT GND VBAT GND GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 R51 R31 C21 C30 L JP6 GP1 GP2 L SCL/CTRL1 H JP9 L L H SDA/CTRL0 TxMASK SHORT SCL, SDA, AND TxMASK TO H Figure 4. Measuring Shut-Down Current Rev. 0 | Page 6 of 20 SHORT THIS JUMPER TO SET PART TO I2C MODE ADP1653 06320-004 R27 INT D5 R19 H R26 SCL EN U5 INT STROBE EN C20 STR SHORT EN TO L AN-861 VDD SOFT POWER-DOWN CURRENT The VDD soft power-down current is the current that the part draws when it is enabled but not boosting. It is measured in the same way as the shutdown current. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C15 C16 5V REV 0.4.1 J4 R6 R5 R4 R3 SETI J6 D7 R23 D6 R20 GP1 GND J8 R2 ANALOG DEVICES SHORT THIS JUMPER C1 GND J1 OUT SETF L1 J5 Tx R66 R25 D1 D2 SHARP R1 C2 J3 C3 J2 D3 JP3 GND GND D10 HPLED U4 JP11 JP10 H NOTES 1. USE THICK, SHORT CABLES. SDA R65 VIC VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 GP2 INT SCL VIC VBAT SETT STR R64 C17 C14 R22 R24 C19 EN J7 GND VBAT GND VBAT U2 C10 C11 JP12 5V C6 SDA R51 GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 L JP6 R31 GP1 GP2 L SCL/CTRL1 H JP9 L L H SDA/CTRL0 TxMASK SHORT SCL, SDA, AND TxMASK TO H ADP1653 Figure 5. Measuring Soft Power-Down Current Rev. 0 | Page 7 of 20 SHORT THIS JUMPER TO SET PART TO I2C MODE 06320-005 R27 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H AN-861 VDD OPERATING CURRENT ILED REGISTER = 001 The test setup for this is the same as that of the soft power-down current. With the device powered up, use the software to program 001 to the ILED register and read the supply current from the ammeter. To get an accurate reading, make sure the scale of the ammeter is set to larger than hundreds of microamperes. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE SUPPLY CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER R27 C31 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C15 C16 INT 5V R25 REV 0.4.1 R6 R5 R4 R3 SETI J6 D6 R20 D7 R23 GND GP1 J4 GND R2 ANALOG DEVICES C1 GND J1 OUT SETF L1 J5 Tx R66 VIC D1 D2 SHARP R1 C2 J3 C3 J2 D3 JP3 GND GND D10 HPLED U4 JP11 JP10 VBAT 1.8V 3.3V H ADI USB/I2C INTERFACE 0.4 SETT J8 SCL SDA R65 VIC VBAT GP2 EN J7 STR R64 C17 C14 R22 R24 C19 VBAT GP1 GP2 VBAT GND GND U2 C10 C11 JP12 5V C6 SDA R51 C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 L JP6 R31 C21 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H L SCL/CTRL1 H JP9 L L H SDA/CTRL0 TxMASK SHORT THIS JUMPER TO SET PART TO I2C MODE NOTES 1. USE THICK, SHORT CABLES. SHORT TxMASK TO L Figure 6. Measuring Supply Current (ILED) Rev. 0 | Page 8 of 20 06320-006 ADP1653 SHORT SCL AND SDA TO H AN-861 VDD OPERATING CURRENT HPLED REGISTER = 001 (BOOST NOT RUNNING, ONE LED) This test measures the supply current when the HPLED register is set to 001, the ILED register is set to 0, and the part is not boosting. This means only one LED is on, and VBAT is greater than VOUT. To measure the supply current with boost disabled, place a jumper on J2 to short out one of the LEDs, and make sure the supply voltage is greater than the forward voltage of the diode. The Tx mask voltage can be set to either HI, LO, or left floating. The current is different in each case. See the ADP1653 data sheet for more information on Tx mask. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER R27 C31 U3 MINI USB SHORT VIC TO 3.3V C51 C8 C19 C15 C16 5V R25 J1 SHORT THIS JUMPER OUT D1 D2 J3 C3 R2 SHARP R1 C2 J2 D3 JP3 GND REV 0.4.1 D7 R23 D6 R20 GP1 GP2 SDA GND R6 R5 R4 R3 SETI J6 VIC GND D10 HPLED U4 JP11 JP10 VBAT 1.8V 3.3V H ADI USB/I2C INTERFACE 0.4 J4 Tx R66 VIC VBAT SDA R65 ANALOG DEVICES GND SETF L1 J5 INT SCL C17 C14 R22 R24 J8 STR R64 GND C1 SETT J7 EN U2 C10 C11 JP12 5V C6 VBAT GP1 GP2 VBAT GND GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 R51 R31 C21 C30 L JP6 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H L SCL/CTRL1 H JP9 L L H SDA/CTRL0 TxMASK SHORT THIS JUMPER TO SET PART TO I2C MODE SHORT THESE JUMPERS NOTES 1. USE THICK, SHORT CABLES. SWITCH TxMASK TO DESIRED SETTING Figure 7. Measuring Supply Current (HPLED—Boost Disabled) Rev. 0 | Page 9 of 20 06320-007 ADP1653 SHORT SCL AND SDA TO H AN-861 VDD OPERATING CURRENT HPLED REGISTER = 001 (BOOST RUNNING, TWO LEDs) This test measures the supply current when the HPLED register is set to 001, the ILED register is set to 0, and the part is boosting. Therefore, both LEDs should be on and Jumper J2 should not be shorted. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER R27 C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C14 R22 R24 C19 C15 C16 5V Tx R66 R25 R6 R5 R4 R3 SETI J6 J1 JP11 H L SCL/CTRL1 H OUT D2 J3 C3 R2 SHARP R1 C2 J2 D3 JP3 U4 JP10 SHORT THIS JUMPER D1 GND REV 0.4.1 D7 R23 D6 R20 GND GP1 J4 VIC VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 J8 SDA R65 ANALOG DEVICES GND SETF L1 J5 INT SCL GND C1 SETT STR VIC VBAT GP2 EN R64 C17 J7 GP1 GP2 VBAT GND VBAT U2 C10 C11 JP12 5V C6 SDA R51 GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 L JP6 R31 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H GND D10 HPLED SHORT THIS JUMPER JP9 L L H SDA/CTRL0 TxMASK SHORT THIS JUMPER TO SET PART TO I2C MODE NOTES 1. USE THICK, SHORT CABLES. SWITCH TxMASK TO DESIRED SETTING Figure 8. Measuring Supply Current (HPLED—Boost Enabled) Rev. 0 | Page 10 of 20 06320-008 ADP1653 SHORT SCL AND SDA TO H AN-861 UNDERVOLTAGE LOCKOUT THRESHOLD (UVLO) The first voltage at which the ILED is able to turn on is the UVLO (VDD rising). To measure UVLO (VDD falling), power up the part and use the software to turn on the ILED. Then slowly decrease the supply voltage in 1 mV steps until the ILED turns off. The voltage at which turn-off occurs is the UVLO (VDD falling). The UVLO is the VBAT voltage required to turn on or turn off the part. There are two UVLOs: UVLO (VDD rising) is the voltage at which the part turns on, and UVLO (VDD falling) is the voltage at which the part turns off. To measure UVLO (VDD rising), apply a low voltage to the part and slowly increase it, 1 mV at a time. For each increase in the voltage steps, use the software to try to turn on the ILED. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER R27 C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C19 C15 C16 5V SCL J4 Tx R66 R25 R6 R5 R4 R3 SETI J6 R2 REV 0.4.1 H L SCL/CTRL1 H SHORT THESE JUMPERS OUT D1 D2 SHARP R1 C2 J3 C3 J2 D3 JP3 LIGHT ILED UP JP11 JP10 ANALOG DEVICES GND J1 GND U4 D7 R23 D6 R20 GP1 GND J8 SDA R65 GND C1 SETF L1 J5 INT VIC VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 SETT STR VIC VBAT GP2 EN R64 C17 C14 R22 R24 J7 GP1 GP2 VBAT GND VBAT U2 C10 C11 JP12 5V C6 SDA R51 GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 L JP6 R31 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H JP9 L L H SDA/CTRL0 TxMASK GND D10 HPLED SHORT THIS JUMPER SHORT THIS JUMPER TO SET PART TO I2C MODE NOTES 1. USE THICK, SHORT CABLES. SWITCH TxMASK TO DESIRED SETTING Figure 9. Measuring UVLO (Rising and Falling) Rev. 0 | Page 11 of 20 06320-009 ADP1653 SHORT SCL AND SDA TO H AN-861 To measure this voltage, first power up the part and use the software to turn on the ILED. Then apply an external voltage to the OUT pin and keep raising it until the ILED turns off. That voltage is the overvoltage threshold. OUT OVERVOLTAGE THRESHOLD The ADP1653 has a safety feature that turns itself off when the voltage at the OUT pin rises above 10.2 V (nominal). VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER R27 C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C15 C16 5V INT SCL SDA R25 REV 0.4.1 R6 R5 R4 R3 SETI J6 R2 H L SCL/CTRL1 H SHORT THESE JUMPERS FORCE A HIGH VOLTAGE AT OUT PIN OUT D1 D2 SHARP R1 C2 J3 C3 JP9 L L H SDA/CTRL0 TxMASK POWER SUPPLY J2 D3 JP3 LIGHT ILED UP JP11 JP10 ANALOG DEVICES GND J1 GND U4 D7 R23 D6 R20 GP1 GND GP2 J4 GND C1 SETF L1 J5 Tx R66 VIC VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 J8 STR R65 VIC VBAT EN SETT J7 GP1 GP2 VBAT GND VBAT R64 C17 C14 R22 R24 C19 R51 GND U2 C10 C11 JP12 5V C6 SDA L C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 JP6 R31 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H GND D10 HPLED SHORT THIS JUMPER SHORT THIS JUMPER TO SET PART TO I2C MODE SWITCH TxMASK TO DESIRED SETTING NOTES 1. USE THICK, SHORT CABLES. Figure 10. Measuring Overvoltage Protection Rev. 0 | Page 12 of 20 06320-010 ADP1653 SHORT SCL AND SDA TO H AN-861 LX SWITCHING FREQUENCY VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT VOLTMETER 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY AMMETER R27 C31 U3 MINI USB SHORT VIC TO 3.3V C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 C51 C8 C6 C11 C19 C15 C16 J8 SCL Tx R6 R5 J4 R4 R3 SETI VIC J6 REV 0.4.1 H H L SCL/CTRL1 SHORT THESE JUMPERS OUT D1 SCOPE D2 SHARP R1 C2 J3 C3 J2 D3 JP3 R2 GND GND JP11 D7 R23 J1 U4 JP10 ANALOG DEVICES GND SETF L1 J5 R66 GND C1 SETT INT SDA D6 R20 GP1 GND GP2 SDA J7 STR R25 VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 EN R65 VIC VBAT VBAT GP1 GP2 VBAT GND R64 C17 C14 R22 R24 JP12 5V 5V R51 GND U2 C10 R50 JP13 L R31 C21 C30 JP6 INT D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT EN TO H D10 HPLED SHORT THIS JUMPER JP9 SHORT THIS JUMPER TO SET PART TO I2C MODE L L H SDA/CTRL0 TxMASK ADP1653 SWITCH TxMASK TO DESIRED SETTING 06320-011 NOTES 1. USE THICK, SHORT CABLES. SHORT SCL AND SDA TO H Figure 11. Measuring Switching Frequency To see the LX switching waveform, power on the device and use the software to turn on the HPLEDs. Probe the test point right above Diode D1. Then, using the cursor function on the scope, measure the switching frequency. Δ: 1.20MHz @: 1.20MHz 1 06320-012 Note that some switching waveforms contain ringing that should be included in the switching frequency measurement. The ringing is caused by the part going into the discontinuous mode of operation (the inductor current ripple dropping to 0) and is completely normal. Δ: 3.84V @: 1.72V CH1 2.00V M200ns T 50.20% A CH1 5.16V Figure 12. LX Pin, Discontinuous Conduction Mode Rev. 0 | Page 13 of 20 AN-861 OUT SOFT START RAMP VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C11 JP12 C19 INT SCL C15 C16 R66 R25 VIC J6 REV 0.4.1 J1 H H L SCL/CTRL1 OUT SCOPE D2 J3 C3 R2 SHARP R1 C2 J2 D3 JP3 GND GND JP11 JP10 SHORT THESE JUMPERS D1 U4 VBAT 1.8V 3.3V D7 R23 D6 R20 GP1 GND GP2 J8 Tx ANALOG DEVICES GND SETF L1 J5 R6 R5 J4 R4 R3 SETI SDA GND C1 SETT STR R65 VIC ADI USB/I2C INTERFACE 0.4 EN J7 GP1 GP2 VBAT GND VBAT R64 C17 C14 R22 R24 VBAT 5V R51 GND U2 C10 R50 5V C6 SDA L C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 C8 JP13 JP6 R31 INT D5 R19 H R26 INT EN SCL STROBE U5 R27 POWER SUPPLY AMMETER SHORT EN TO H STR C20 VOLTMETER EN PRESS THE STROBE BUTTON TO FLASH 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY D10 HPLED SHORT THIS JUMPER JP9 SHORT THIS JUMPER TO SET PART TO I2C MODE L L H SDA/CTRL0 TxMASK ADP1653 SWITCH TxMASK TO DESIRED SETTING 06320-013 SHORT SCL AND SDA TO H NOTES 1. USE THICK, SHORT CABLES. Figure 13. Measuring OUT Soft Start Ramp The ADP1653 contains a soft start feature at the OUT pin to reduce the output voltage ramp rate. This prevents a large inrush current to the chip, as well as accidental tripping of the overvoltage threshold. To measure the OUT soft start ramp rate, hook up a scope to the OUT pin. In the example shown in Figure 14, the soft start ramp rate is 3.52 V 183 μs = 19.23 V/ μs Δ: 183µs @: –102µs 06320-014 Use the software to program the first flash setting to the part. Program the HPLED register to 0x09 or any other setting, as desired, and press the strobe button to flash the LEDs. Capture the output voltage waveform on the scope, and measure the amount of rise in the output voltage and the time it takes. Dividing the output voltage rise by the time yields the soft start ramp rate. Δ: 3.52V @: 2.88V 1 CH1 1.00V M40.0µs T 50.00% A CH1 Figure 14. Typical Soft Start Ramp Rev. 0 | Page 14 of 20 4.76V AN-861 START-UP INRUSH CURRENT VOLTMETER TO CHECK ACTUAL VBAT VOLTAGE C31 U3 MINI USB SHORT VIC TO 3.3V C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 C51 C8 5V C15 C16 INT SETT J8 J4 Tx R66 R25 REV 0.4.1 R6 R5 R4 R3 SETI J6 H L SCL/CTRL1 H SHORT THESE JUMPERS GND J1 OUT D1 D2 SHARP R1 C2 J3 C3 J2 D3 JP3 R2 GND GND JP11 ANALOG DEVICES C1 U4 JP10 D7 R23 GND SETF L1 J5 SCL SDA D6 R20 GP1 GND GP2 SDA J7 STR VIC VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 EN R65 VIC VBAT VBAT GP1 GP2 VBAT GND GND R64 C17 C14 R22 R24 C19 R51 U2 C11 JP12 5V C6 C10 R50 JP13 L R31 C21 C30 JP6 INT D5 R19 H R26 SCL EN INT STROBE U5 R27 POWER SUPPLY SCOPE SHORT EN TO H STR C20 VOLTMETER EN PRESS THE STROBE BUTTON TO FLASH 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY D10 HPLED SHORT THIS JUMPER JP9 L L H SDA/CTRL0 TxMASK SHORT THIS JUMPER TO SET PART TO I2C MODE ADP1653 SWITCH TxMASK TO DESIRED SETTING 06320-015 NOTES 1. USE THICK, SHORT CABLES. SHORT SCL AND SDA TO H Figure 15. Measuring Inrush Current at Startup When the ADP1653 first starts boosting, it may initially draw slightly more current than required, which is known as the start-up inrush current. To measure the inrush current, place a current probe on the positive power supply cable, use the software to program the HPLED register to the desired setting (press the strobe button if in the flash mode), and capture the input current waveform on the scope. 1 06320-016 Figure 16 shows an example of the start-up inrush current, and the overshoot is the inrush current. How much overshoot there is depends on the external components, such as the input/output capacitors. CH1 MAX 28.0mV CH1 10.0mV Ω M100µs T 0.0s A CH1 15.4mV Figure 16. Typical Supply Inrush Current Waveform Rev. 0 | Page 15 of 20 AN-861 Under normal boost conditions, VLED ≈ 6.5 V; therefore, POUT = 3.25 W, and the efficiency loss due to the sense resistor is 0.77%. The user can add that loss back to the calculated efficiency to get the real efficiency. EFFICIENCY Torch Mode LED efficiency is computed using the following equation: VLED × I OUT V BAT × I IN When measuring VLED, the two terminals of the voltmeter must be connected to the OUT pin and the HPLED pin, respectively. This measures the voltage across the LEDs, and the efficiency computed from it is the LED efficiency. If the negative terminal of the voltmeter is connected to ground, then the voltage measured is the pure boosted output voltage, and the efficiency calculated is the boost efficiency. The LED efficiency is always lower than the boost efficiency, because there is approximately a 350 mV loss at the HPLED pin when the part is boosting. The user must first measure VLED, IOUT, VBAT, and IIN separately. VBAT and IIN are easily measured with a voltmeter and an ammeter. For IOUT, it is recommended that a high power currentsensing resistor of a small value be used, such as 0.1 Ω. Solder the leads of the resistor directly onto Jumper J3 without using any wires, because the wire resistance could be on the same order of magnitude as that of the resistor. Measure the voltage drop across the resistor and divide it by the resistance to compute the output current. Note that there is some loss in efficiency due to the current-sensing resistor. The amount of loss depends on the size of the resistor. For example, if R = 0.1 Ω and IOUT = 500 mA, then VLOSS = 0.05 V and PLOSS = 25 mW. In addition, when measuring the efficiency at different output currents and a fixed VBAT voltage, increasing the output current inevitably decreases the supply voltage that the part receives due to the internal resistance of the cables. As a result, the user must adjust the power supply so the voltage at the VBAT pin stays constant. VOLTMETER AMMETER TO CHECK ACTUAL TO MEASURE VBAT VOLTAGE INPUT CURRENT C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C11 C19 C15 C16 5V SETF L1 SCL Tx R6 R5 J4 R4 R3 SETI VIC J6 SDA R66 REV 0.4.1 D7 R23 D6 R20 GP1 GND GP2 INT J5 R25 GND J8 R2 ANALOG DEVICES SHORT THESE JUMPERS C1 GND J1 OUT MEASURE LED VOLTAGE D1 D2 SHARP R1 C2 J3 C3 J2 D3 JP3 GND VOLTMETER GND D10 HPLED U4 JP11 JP10 VBAT 1.8V 3.3V H ADI USB/I2C INTERFACE 0.4 SETT STR R65 VIC VBAT J7 EN GP1 GP2 VBAT GND VBAT R64 C17 C14 R22 R24 JP12 R51 GND U2 C10 R50 5V C6 SDA L C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 C8 JP13 JP6 R31 INT D5 R19 H R26 INT EN SCL STROBE U5 R27 POWER SUPPLY AMMETER SHORT EN TO H STR C20 VOLTMETER EN PRESS THE STROBE BUTTON TO FLASH 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY L SCL/CTRL1 H JP9 L L H SDA/CTRL0 TxMASK SHORT THIS JUMPER TO SET PART TO I2C MODE HIGH POWER CURRENT SENSING RESISTOR MEASURE LED CURRENT VOLTMETER NOTES 1. USE THICK, SHORT CABLES. SWITCH TxMASK TO DESIRED SETTING Figure 17. Measuring Efficiency in Torch Mode Rev. 0 | Page 16 of 20 06320-017 ADP1653 SHORT SCL AND SDA TO H AN-861 To measure IIN, use a current probe on the power supply cable. To measure IOUT, place a thick wire loop on Jumper J3 and use another current probe to measure the current. Flash Mode Efficiency measurement in the flash mode is not as straightforward as in the torch mode because the boost only lasts less than a second. As a result, scopes must be used to capture the waveforms. Use a 4-channel scope to capture VBAT, IIN, VOUT, and IOUT, and use a separate scope to probe VHPLED. Subtracting VHPLED from VOUT gives VLED. Keep in mind that scopes do not have as much resolution as a voltmeter or ammeter, so the flash efficiency computed may have some error. It is advisable to use a calibrated electronic load to do regular probe calibration of the wire used in the measurement. 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY PRESS THE STROBE BUTTON TO FLASH POWER SUPPLY SHORT EN TO H R27 C31 C21 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C15 C16 5V EN INT J8 SCL SDA J4 Tx R66 R25 REV 0.4.1 R6 R5 R4 R3 SETI R2 ANALOG DEVICES SHORT THESE JUMPERS C1 GND J1 OUT SETF L1 J6 D7 R23 GND VBAT SETT J5 GP1 GP2 D6 R20 GP1 GND GP2 J7 STR VIC D1 D2 SHARP R1 C2 J3 C3 J2 D3 D10 HPLED JP3 GND GND U4 JP11 JP10 VBAT 1.8V 3.3V H ADI USB/I2C INTERFACE 0.4 VBAT R65 VIC VBAT INT GND GND R64 C17 C14 R22 R24 C19 R51 U2 C10 C11 JP12 5V C6 SDA L C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 JP6 R31 4-CHANNEL SCOPE D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR CURRENT PROBE L SCL/CTRL1 H CURRENT PROBE JP9 L L H SDA/CTRL0 TxMASK SHORT THIS JUMPER TO SET PART TO I2C MODE SCOPE NOTES 1. USE THICK, SHORT CABLES. SWITCH TxMASK TO DESIRED SETTING Figure 18. Measuring Efficiency in Flash Mode Rev. 0 | Page 17 of 20 06320-018 ADP1653 SHORT SCL AND SDA TO H AN-861 CURRENT LIMIT 2.7V TO 5.5V, 2.0A SUPPLY OR BATTERY POWER SUPPLY PRESS THE STROBE BUTTON TO FLASH SHORT EN TO H R27 C21 C31 U3 C30 MINI USB SHORT VIC TO 3.3V C8 C11 C19 R65 C15 C16 VIC J6 REV 0.4.1 D7 R23 D6 R20 GP1 GND GP2 SDA Tx R6 R5 J4 R4 R3 SETI R25 VIC OUT D1 D2 J3 C3 R2 SHARP R1 C2 J2 D3 D10 HPLED JP3 GND GND U4 VBAT 5V SCL R66 GND PROBE J1 SETF L1 J5 ANALOG DEVICES CURRENT J8 INT SDA GND C1 SETT J7 STR R64 C17 C14 R22 R24 JP12 5V C6 EN GP1 GP2 VBAT GND VBAT U2 C10 R50 JP13 R51 GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 C51 INT L JP6 R31 4-CHANNEL SCOPE D5 R19 H R26 INT EN U5 SCL STROBE EN C20 STR SHORT THIS JUMPER JP11 JP10 VBAT 1.8V 3.3V H ADI USB/I2C INTERFACE 0.4 H L SCL/CTRL1 CURRENT PROBE JP9 SHORT THIS JUMPER TO SET PART TO I2C MODE L L H SDA/CTRL0 TxMASK ADP1653 NOTES 1. USE THICK, SHORT CABLES. SWITCH TxMASK TO DESIRED SETTING 06320-019 SHORT SCL AND SDA TO H Figure 19. Measuring Current Limit The purpose of the current limit is to restrict the amount of input current so the battery does not get overloaded. When the current limit is reached, both the input and LED currents stop increasing, even if the user tries to program a higher LED current setting. To measure the current limit, place a thick wire loop on Jumper J1 and use a current probe to capture the inductor current waveform on the scope. Then, use the software to increase the LED current setting, until a point when the inductor current stops increasing. The peak of the inductor current is the current limit. Figure 20 shows the inductor current ripple when the current has NOT been reached, and Figure 21 shows when the current limit has been reached. In the figures, Channel 1 is input voltage, Channel 2 is inductor current ripple, and Channel 4 is output current. Δ: 3.60V @: 3.60V 1 CH2 MAX 1.43A Δ: 3.60V @: 3.60V CH2 MAX 1.9A 2 06320-020 2 4 CH1 5.00V CH2 500mA Ω CH4 10.0mV Ω M1.00µs T 50.60% A CH2 06320-021 1 It may be useful, as well, to measure the LED current to know the maximum LED current that can be achieved with the particular external components. 4 CH1 5.00V 1.18A CH2 500mA Ω CH4 10.0mV Ω M1.00µs T 50.60% A CH2 1.18A Figure 21. Inductor Current Waveform at Current Limit Figure 20. Inductor Current Waveform Rev. 0 | Page 18 of 20 AN-861 LINE REGULATION VBAT1 R27 C31 U3 C30 MINI USB SHORT VIC TO 3.3V C51 C8 C11 C19 C15 C16 5V R65 SCL Tx R6 R5 J4 R4 R3 SETI VIC J6 R66 D7 R23 D6 R20 GP1 J5 J1 OUT D2 JP11 H L SCL/CTRL1 H SHARP R1 C2 J3 C3 J2 D3 D10 HPLED JP3 R2 GND U4 JP10 SHORT THESE JUMPERS D1 GND REV 0.4.1 ANALOG DEVICES GND SETF L1 INT R25 VBAT 1.8V 3.3V ADI USB/I2C INTERFACE 0.4 GND STR VIC VBAT J8 SDA GND C1 SETT J7 EN R64 C17 C14 R22 R24 JP12 5V C6 VBAT GP1 GP2 VBAT GND U2 C10 GP2 R51 GND C5 D8 USB_OK C7 R21 C12 C18 C9 C50 R62 R30 C13 R63 R50 JP13 L JP6 R31 C21 INT D5 R19 H R26 SDA EN INT STROBE U5 SCL SHORT EN TO H STR C20 SCOPE VBAT2 EN PRESS THE STROBE BUTTON TO FLASH SHORT THIS JUMPER JP9 SHORT THIS JUMPER TO SET PART TO I2C MODE L L H SDA/CTRL0 TxMASK ADP1653 SWITCH TxMASK TO DESIRED SETTING 06320-022 NOTES 1. USE THICK, SHORT CABLES. SHORT SCL AND SDA TO H Figure 22. Measuring Line Regulation Figure 23 shows the line regulation when VBAT1 = 3.3 V and VBAT2 = 4.0 V. Because ADP1653 is a current-mode controller, it is insensitive to changes in the supply voltage, and the line regulation is very good. 1 2 06320-023 Line regulation measures how much the output voltage changes in response to a change in the input voltage. To test this, the setup shown in Figure 22 can be used with two high power Schottky diodes and a P-channel power MOSFET. Use a function generator to generate a square wave for the gate of the MOSFET. If VBAT1 < VBAT2, when the gate of the MOSFET is low, the top diode is reverse-biased, and VBAT = VBAT2. When the gate is high, the bottom diode is reverse-biased, and VBAT = VBAT1. CH1 = VBAT CH2 = VOUT CH1 1.00V CH2 2.00V M100ms T 40.60% A CH1 Figure 23. Typical Line Regulation Plot Rev. 0 | Page 19 of 20 3.68V AN-861 NOTES ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. AN06320-0-3/07(0) Rev. 0 | Page 20 of 20
