EN5322QI Created on 2/27/2007 11:55:00 AM 2 A Voltage Mode Synchronous Buck PWM DC-DC Converter with Integrated Inductor RoHS Compliant Halogen Free General Description Features The EN5322 provides the benefits of high switching frequency with the flexibility to optimize the design for footprint or efficiency. • Revolutionary Integrated Inductor • Total Footprint as Small as 60 mm2 • 4 mm x 6 mm x 1.1 mm QFN Package • 4 MHz Fixed Switching Frequency • High Efficiency, up to 93 % • 2% Initial VOUT Accuracy with VID Codes • 2% Initial 0.6 V Feedback Voltage Accuracy • 2.4 V to 5.5 V Input Voltage Range • 2 A Output Current Capability • Fast Transient Response • Low Ripple Voltage; 8 mVP-P Typical • Low Dropout Operation: 100 % Duty Cycle • Power OK Signal with 5 mA Sink Capability • Dynamic Voltage Scaling with VID Codes • 17 μA Typical Shutdown Current • Under Voltage Lockout, Over Current, Short Circuit, and Thermal Protection • RoHS Compliant; MSL 3 260 °C Reflow The 4 MHz operation allows for the use of tiny MLCC capacitors. It also enables a very wide control loop bandwidth providing excellent transient performance and reduced output impedance. The internal compensation is designed for unconditional stability. Three VID output voltage select pins provide seven pre-programmed output voltages along with an option for external resistor divider. Output voltage can be programmed on-the-fly to provide fast, dynamic voltage scaling with smooth transitions between programmed output voltages. Applications • • • • • • • • Point of Load Regulation for Low Power Processors, Network Processors, DSPs’ FPGAs and ASICs Replacement of LDOs Servers, Desktop Computers, Notebooks and UMPC Storage and Networking Instrumentation DSL, STB, DVR, DTV, and iPC Computer Peripherals Audio Application Circuit ENABLE VIN 10 uF CBYPASS 470 pF VSENSE PVIN VS0 VS1 VOUT VOUT EN5322 POK COUT 47 uF VS2 PGND AVIN PGND AGND 1 uF Ordering Information Part Number EN5322QI-T EN5322QI-E CIN Figure 1. Application Circuit Temp Rating (°C) Package -40 to +85 24-pin QFN T&R QFN Evaluation Board ©Enpirion 2007 all rights reserved, E&OE 1 www.enpirion.com October 2007 EN5322QI Absolute Maximum Ratings CAUTION: Absolute maximum ratings are stress ratings only. Functional operation beyond recommended operating conditions is not implied. Stress beyond absolute maximum ratings may cause permanent damage to the device. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. Absolute Maximum Electrical Ratings MIN Voltages on: PVIN, AVIN, VOUT Voltages on: VSENSE, VS0, VS1, VS2, ENABLE, POK Voltage on: VFB ESD Rating (Human Body Model) ESD Rating (Charge Device Model) MAX -0.3 V -0.3 V -0.3 V 2 kV 500 V 6.5 V VIN 2.7 V -40 °C -65 °C +85 °C +150 °C +260 °C Absolute Maximum Thermal Ratings Ambient Operating Range Storage Temperature Range Reflow Peak Body Temperature MSL3 (10 s) Thermal Characteristics PARAMETER Thermal Shutdown Thermal Shutdown Hysteresis Thermal Resistance: Junction to Case Thermal Resistance: Junction to Ambient SYMBOL MIN TSD TSDH θJC θJA TYP 155 15 6 36 MAX UNITS °C °C °C/W °C/W Recommended Operating Conditions PARAMETER SYMBOL MIN Input Voltage Range VIN 2.4 Output Voltage Range VOUT 0.6 Output Current ILOAD 0 Operating Junction Temperature TJ 0 Note: VDROPOUT is defined as (ILOAD x Dropout Resistance) including temperature effect. VIN MAX 5.5 - VDROPOUT 2 +125 UNITS V V A °C Electrical Characteristics VIN = 5 V and TA = 25 °C, unless otherwise noted. Note 1: The tolerances with VID codes hold true only if VIN is greater than (VOUT + VDROPOUT). Note 2: VFB, ENABLE, VS0-VS2 pin input current specification is guaranteed by design. PARAMETER Operating Input Voltage Under Voltage Lockout UVLO Hysteresis Output Voltage with VID Codes (Note 1) VFB Voltage SYMBOL VIN VUVLO TEST CONDITIONS VIN going low to high VOUT ILOAD = 100 mA VS2 VS1 VS0 VOUT (V) 0 0 0 3.3 0 0 1 2.5 0 1 0 1.8 0 1 1 1.5 1 0 0 1.25 1 0 1 1.2 1 1 0 0.8 VFB ILOAD = 100 mA, VS0 = VS1 = VS2 = 1 ©Enpirion 2007 all rights reserved, E&OE MIN 2.4 2 TYP MAX 5.5 2.2 0.15 +2.0 +2.0 +2.0 +2.0 +2.0 +2.0 +2.0 -2.0 -2.0 -2.0 -2.0 -2.0 -2.0 -2.0 0.588 0.600 0.612 UNITS V V V % V www.enpirion.com October 2007 PARAMETER Output Voltage with VID Codes (Note 1) VFB Voltage Dynamic Voltage Slew Rate Soft Start Slew Rate Line Regulation Load Regulation VFB, ENABLE, VS0-VS2 Pin Input Current (Note 2) ENABLE, VS0-VS2 Voltage Threshold POK Upper Threshold POK Upper Threshold POK Lower Threshold POK Lower Threshold POK Low Voltage POK Pin VOH Leakage Current Shutdown Current Quiescent Current Quiescent Current Current Limit Threshold PFET On Resistance NFET On Resistance Dropout Resistance Operating Frequency Output Ripple Voltage EN5322QI SYMBOL TEST CONDITIONS VOUT 2.4 V ≤ VIN ≤ 5.5 V, ILOAD = 0 ~ 2 A, TA = -40 ~ +85 °C VS2 VS1 VS0 VOUT (V) 0 0 0 3.3 0 0 1 2.5 0 1 0 1.8 0 1 1 1.5 1 0 0 1.25 1 0 1 1.2 1 1 0 0.8 VFB 2.4 V ≤ VIN ≤ 5.5 V, ILOAD = 0 ~ 2 A, VS0 = VS1 = VS2 = 1, TA = -40 ~ +85 °C MIN TYP +3.0 +3.0 +3.0 +3.0 +3.0 +3.0 +3.0 -3.0 -3.0 -3.0 -3.0 -3.0 -3.0 -3.5 0.582 0.600 TA = -40 ~ +85 °C 0.0 1.4 111 102 92 90 0.15 POK High, TA = -40 ~ +85 °C ENABLE Low No Switching Switching, VOUT = 1.2 V 2.4 V ≤ VIN ≤ 5.5 V FOSC VRIPPLE ©Enpirion 2007 all rights reserved, E&OE COUT = 2 x 22 μF 0805 X5R MLCC, VOUT = 1.2 V, ILOAD = 2 A 3 0.618 1.5 1.5 0.033 0.13 2.4 V ≤ VIN ≤ 5.5 V, VOUT = 1.2 V 0 A ≤ ILOAD ≤ 2 A, , VOUT = 1.2 V Logic Low Logic High VOUT Rising VOUT Falling VOUT Rising VOUT Falling ISINK = 5 mA, TA = -40 ~ +85 °C MAX UNITS % V V/ms V/ms %/V %/A +/-40 nA 0.4 VIN V 0.4 % % % % V 500 nA 160 60 200 4 μA μA mA A mΩ mΩ mΩ MHz 8 mVP-P 17 800 15 2.1 www.enpirion.com October 2007 EN5322QI Pin Configuration NOTE: NC(SW) pins are not to be electrically connected to any external signal, ground, or voltage. However, they must be soldered to the PCB. Failure to follow this guideline may result in part malfunction or damage. Figure 1. Pin Diagram, Top View. Pin Description PIN NAME 1, 21-24 NC(SW) 2-3, 8-9 PGND 4-7 VOUT 10-12 VS2-0 13 VSENSE 14 VFB 15 AGND 16 AVIN 17 POK 18 ENABLE 19-20 PVIN FUNCTION No Connect. These pins are internally connected to the common drain output of the internal MOSFETs. NC(SW) pins are not to be electrically connected to any external signal, ground, or voltage. However, they must be soldered to the PCB. Failure to follow this guideline may result in part malfunction or damage. Input/Output Power Ground. Connect these pins to the ground electrode of the input and output filter capacitors. Refer to Layout Considerations section for details. Voltage and Power Output. Connect these pins to output capacitor(s). Output Voltage Select. These pins set one of seven preset output voltages and the external divider option (refer to Electrical Characteristics table for more details), and can be directly pulled up to VIN or pulled down to GND. Sense Pin for Internally Programmed Output Voltages with VID Codes. Connect this pin to the last local output filter capacitor at all times for internal compensation. Feedback Pin for External Voltage Divider Network. Connect a resistor divider to this pin to set the output voltage. Use 340 kΩ, 1% or better for the upper resistor. Analog Ground for the Controller Circuits Analog Voltage Input for the Controller Circuits. Connect this pin to the input power supply. Use a 1 μF bypass capacitor on this pin. Power OK with an Open Drain Output. Refer to Power OK section. Input Enable. A logic high signal on this pin enables the output and initiates a soft start. A logic low signal disables the output and discharges the output to GND. This pin must not be left floating. Input Power Supply. Connect to input supply. Decouple with input capacitor(s) to PGND. ©Enpirion 2007 all rights reserved, E&OE 4 www.enpirion.com October 2007 EN5322QI Functional Block Diagram PVIN POK UVLO POK Thermal Limit Current Limit ENABLE NC (SW) Soft Start P-Drive Logic (-) VOUT PWM Comp (+) N-Drive PGND VSENSE Sawtooth Generator Compensation Network (-) Switch VFB Error Amp (+) DAC Voltage Select VREF BIAS Package Boundary AVIN AGND VS0 VS1 VS2 Figure 3. Functional Block Diagram. ©Enpirion 2007 all rights reserved, E&OE 5 www.enpirion.com October 2007 EN5322QI ENABLE VS0 VS1 VS2 VIN VS0 VS1 ENABLE VSENSE VS2 EN5322 PVIN CIN-1 10 uF 10 V 0805 CIN-2 CIN-3 470 pF 1 uF 0603 VOUT VOUT AVIN PGND AGND POK COUT-1 COUT-2 22 uF 6.3 V 0805 22 uF 6.3 V 0805 RPOK* 100 k 5% POK * Leave RPOK open if the POK function is not used. Figure 4. Typical Application Circuit with VID Codes. Typical Performance Characteristics Circuit of Figure 4, VIN = 5 V, VOUT = 1.2 V and TA = 25°C, unless otherwise noted. Efficiency vs. Load Current (Vin = 3.3 V) 100 100 90 90 Efficiency (%) Efficiency (%) Efficiency vs. Load Current (Vin = 5 V) 80 70 60 50 80 70 60 50 40 40 30 30 0 0.4 0.8 1.2 1.6 0 2 0.8 1.2 1.6 2 Load Current (A) Load Current (A) Top to Bottom: VOUT = 3.3 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V, 0.8 V ©Enpirion 2007 all rights reserved, E&OE 0.4 6 Top to Bottom: VIN = 2.5 V, 1.8 V, 1.5 V, 1.2 V, 0.8 V www.enpirion.com October 2007 EN5322QI Quiescent Current (Switching) vs. Input Voltage Quiescent Current (mA) Quiescent Current (uA) Quiescent Current (No Switching) vs. Input Voltage 840 820 800 780 760 740 2 3 4 5 18 16 14 12 10 8 2 6 3 4 5 6 Input Voltage (V) Input Voltage (V) Output Voltage (V) Load Regulation (Vin = 5 V) 1.202 1.200 1.198 1.196 1.194 1.192 1.190 0 0.4 0.8 1.2 1.6 2 Load Current (A) Output Ripple at 2 A Load (VIN = 5 V ) CH2: VOUT ©Enpirion 2007 all rights reserved, E&OE Output Ripple at 2 A Load (VIN = 3.3 V ) CH2: VOUT 7 www.enpirion.com October 2007 EN5322QI Transient Response at VIN = 5 V (0-2 A Load Step) CH2: VOUT, CH4: ILOAD Transient Response at VIN = 3.3 V (0-2 A Load Step) CH2: VOUT, CH4: ILOAD VOUT Scaling with VID Codes at VIN = 5 V (VOUT = 1.2 V-2.5 V) CH1: VS2, CH2: VOUT, CH3: POK VOUT Scaling with VID Codes at VIN = 3.3 V (VOUT = 1.2 V-2.5 V) CH1: VS2, CH2: VOUT, CH3: POK Power Up/Down at No Load CH1: ENABLE, CH2: VOUT, CH3: POK, CH4: IINDUCTOR Power Up/Down at 0.6 Ω Load CH1: ENABLE, CH2: VOUT, CH3: POK, CH4: IINDUCTOR ©Enpirion 2007 all rights reserved, E&OE 8 www.enpirion.com October 2007 EN5322QI Output Over Load at No Load CH1: VOUT, CH2: VNC(SW), CH3: POK, CH4: IINDUCTOR Output Over Load at 2 A Load CH1: VOUT, CH2: VNC(SW), CH3: POK, CH4: IINDUCTOR Output Over Load at No Load CH1: VOUT, CH2: VNC(SW), CH3: POK, CH4: IINDUCTOR Output Over Load at 2 A Load CH1: VOUT, CH2: VNC(SW), CH3: POK, CH4: IINDUCTOR Functional Description The EN5322 leverages advanced CMOS technology to provide high switching frequency, while also maintaining high efficiency. The converter uses voltage mode control to provide a high noise immunity, low output impedance and excellent load transient response. No external compensation components are needed. Packaged in a 4 mm x 6 mm x 1.1 mm QFN, the EN5322 provides a high degree of flexibility in circuit design while maintaining a very small footprint. High switching frequency allows for the use of very small MLCC input and output filter capacitors. ©Enpirion 2007 all rights reserved, E&OE Output voltage is chosen from one of seven preset values via a three-pin VID voltage select scheme. An external divider option enables the selection of any output voltage ≥ 0.6 V. The VID pins can be toggled dynamically to implement glitch-free dynamic voltage scaling. 9 www.enpirion.com October 2007 POK monitors the output voltage and signals if it is in regulation. Protection features include under voltage lockout (UVLO), over current protection, short circuit protection, and thermal overload protection. EN5322QI voltage reaches sufficient level to ensure proper operation. If the voltage drops below the UVLO threshold the lockout circuitry will again disable switching. Hysteresis is included to prevent chattering between UVLO high and low states. Stability over Wide Range of Operating Conditions Enable The EN5322 utilizes an internal compensation network and is designed to provide stable operation over a wide range of operating conditions. One of the key features of this device is the ability to add supplementary capacitance to the output to improve transient performance or reduce output voltage ripple with dynamic loads. The EN5322 is stable with up to 60 μF of output capacitance at the VSENSE sense point. The high switching frequency allows for a wide control loop bandwidth. The ENABLE pin provides means to shut down the converter or initiate normal operation. A logic high will enable the converter to go through the soft start cycle and regulate the output voltage to the desired value. A logic low will allow the device to discharge the output and go into shutdown mode for minimal power consumption. When the output is discharged, an auxiliary NFET turns on and limits the discharge current to 300 mA or below. In shutdown mode, the device typically drains as little as 17 μA. Soft Start NOTE: The ENABLE pin must not be left floating. The internal soft start circuit limits inrush current to negligible levels when the device starts up from a power down condition or when the ENABLE pin is asserted “high”. Digital control circuitry sets the VOUT ramp rate to minimize input voltage ripple and inrush current to ensure a glitch-free start up. The soft start ramp rate is nominally 1.5 V/ms. Thermal Shutdown When excessive power is dissipated in the device, its junction temperature rises. Once the junction temperature exceeds the thermal shutdown temperature 155 °C, the thermal shutdown circuit turns off the converter, allowing the device to cool. When the junction temperature drops 15 °C, the device will be reenabled and go through a normal startup process. Over Current/Short Circuit Protection Current limit function is implemented by sensing the current flowing through a sense PFET which is then compared to a reference current. When the sensed value exceeds the reference current, the PFET is turned off and the NFET is turned on at the next clock edge, pulling VOUT low. This condition is maintained for a period of 1.2 ms and then a normal soft start cycle is initiated. If the over current condition still persists, this cycle will repeat. Power OK The EN5322 provides an open drain output to indicate if the output voltage stays within 92% to 111% of the set value. Within this range, the POK output is allowed to be pulled high. Outside this range, POK remains low. However, during transitions such as power up, power down, and dynamic voltage scaling, the POK output will not change state until the transition is complete for enhanced noise immunity. Under Voltage Lockout An under voltage lockout circuit will hold off switching during initial power up until the input ©Enpirion 2007 all rights reserved, E&OE 10 www.enpirion.com October 2007 EN5322QI used for minimal current consumption in shutdown mode. The POK has 5 mA sink capability for events where it needs to feed a digital controller with standard CMOS inputs. When POK is pulled high, the pin leakage current is as low as 500 nA maximum over temperature. This allows a large pull up resistor such as 100 kΩ to be The POK output can also be conveniently used as an ENABLE input of the next stage for power sequencing of multiple converters. ENABLE VS0 VS1 VS2 VIN VS0 VS1 VS2 ENABLE VSENSE VOUT PVIN CIN-1 10 uF 10 V 0805 CIN-2 470 pF CIN-3 EN5322 VFB PGND AGND AVIN 1 uF 0603 340 k 1% R1 COUT-1 VOUT COUT-2 1% R2 22 uF 6.3 V 0805 22 uF 6.3 V 0805 POK RPOK* 100 k 5% POK * Leave RPOK open if the POK function is not used. Figure 5. Typical Application Circuit with External Resistor Divider. Application Information Setting the Output Voltage Input and Output Capacitor Selection The output voltage can be set by programming VS0-VS2 pins as shown in the Electrical Characteristics table or by pulling all these VID pins high and using an external voltage divider, as shown in Figure 5. If the external voltage divider option is chosen, use 340 kΩ, 1% or better for the upper resistor R1. Then the value of the bottom resistor R2 in kΩ is given as: Low ESR MLCC capacitors with X5R or X7R or equivalent dielectric should be used for input and output capacitors. Y5V or equivalent dielectrics lose capacitance with frequency, DC bias, and temperature. Therefore, they are not suitable for switch-mode DC-DC converter filtering, and must be avoided. A 10 μF, 10 V, 0805 ceramic capacitor with a 470 pF high frequency bypass capacitor is required on PVIN for all applications. A 1 μF, 10 V, 0603 ceramic capacitor on AVIN is generally sufficient for high frequency bypass to ensure clean chip supply for optimal performance. 204 R2 = kΩ VOUT − 0.6 where VOUT is the output voltage. R2 should also be a 1% or better resistor. ©Enpirion 2007 all rights reserved, E&OE 11 www.enpirion.com October 2007 Two 22 μF, 6.3 V, 0805 ceramic capacitors are recommended on the output for most applications. The output capacitance before the output voltage sense point can be increased to 60 μF to improve load transient response and output ripple. 3. 4. POK Pull Up Resistor Selection POK can be pulled up through a resistor to any voltage source as high as VIN. The simplest way is to connect POK to the power input of the converter through a resistor. A 100 kΩ pull up resistor is typically recommended for most applications for minimal current drain from the voltage source and reasonable noise immunity. 5. 6. Layout Considerations Proper layout and placement of external components is critical to optimal functioning of the converter and for minimizing radiated and conducted noise. 7. Following these layout guidelines as demonstrated in the EN5322 customer eval boards: 1. Input and output capacitors should be placed on the same side of the PCB as the EN5322 and immediately adjacent to their respective pins on the package. To minimize parasitic inductances, the traces for making these connections should be as short and wide as possible. 2. A row of vias connecting these capacitors’ ground pads to the PCB GND plane should be placed along the edge of the capacitor ground copper closest to the positive capacitor pads. These vias should start as close to the ©Enpirion 2007 all rights reserved, E&OE 12 EN5322QI device as possible and continue underneath the capacitors. Avoid adding a test pin or test pad for NC(SW) pins on the PCB. Doing so can compromise the GND plane and result in degradation of the performance. There should be as many vias as possible connecting the thermal pad under the device to the PCB GND plane for best thermal performance. Ideally, the vias should have a drill diameter of about 0.3 mm with at least 1 oz copper plating in the barrel. Keep the input and output current loops separate from each other as much as possible by putting a slit in the PGND copper if necessary. Keep sensitive signals on the PCB away from the power supply circuit. Connect the VSENSE trace to the last local output capacitor. Make sure the trace inductance between the output capacitors and the sensing point is minimized. The VSENSE trace should also be kept away from noisy signals that can contaminate it. When using multiple converters on the same PCB, try to minimize any crosstalk between them: - Keep the input circuit of any converter away from the output circuit of any other converter. - Isolate the input circuits from each other by connecting all the inputs to a common point using a start connection. Add a 2.2 μF bypass capacitor at the start connection if necessary. - Add a SMT ferrite bead before the input capacitor of each converter, and a 2.2 μF or similar bypass capacitor before the ferrite bead. www.enpirion.com October 2007 EN5322QI Design Considerations for Lead-Frame Based Modules Exposed Metal Pads on Package Bottom QFN lead-frame based package technology utilizes exposed metal pads on the bottom of the package that provide improved thermal dissipation and low package thermal resistance, smaller package footprint and thickness, large lead size and pitch, and excellent lead co-planarity. As the EN5322 package is a fully integrated module consisting of multiple internal devices, the lead-frame provides circuit interconnection and mechanical support of these devices resulting in multiple exposed metal pads on the package bottom. Only the two large thermal pads and the perimeter leads are to be mechanically/electrically connected to the PCB through a SMT soldering process. All other exposed metal is to remain free of any interconnection to the PCB. Figure 6 shows the recommended PCB metal layout for the EN5322 package. A GND pad with a solder mask "bridge" to separate into two pads and 24 signal pads are to be used to match the metal on the package. The PCB should be clear of any other metal, including traces, vias, etc., under the package to avoid electrical shorting. Solder mask should cover the PCB in all areas under the package. Figure 6. Recommended Footprint for PCB. ©Enpirion 2007 all rights reserved, E&OE 13 www.enpirion.com October 2007 EN5322QI Package and Mechanical ©Enpirion 2007 all rights reserved, E&OE 14 www.enpirion.com October 2007 EN5322QI Additional Products Part Number EP5352QI EP5362QI EP5382QI EQ5352DI EQ5362DI EQ5382DI EN5312QI ER5312DI EN5335QI EN5336QI EN5365QI EN5366QI Description 500 mA dc-dc with integrated inductor; 5 mm x 4 mm x 1.1 mm package 600 mA dc-dc with integrated inductor; 5 mm x 4 mm x 1.1 mm package 800 mA dc-dc with integrated inductor; 5 mm x 4 mm x 1.1 mm package 500 mA dc-dc regulator; tiny 3 mm x 2 mm x 0.9 mm DFN package 600 mA dc-dc regulator; tiny 3 mm x 2 mm x 0.9 mm DFN package 800 mA dc-dc regulator; tiny 3 mm x 2 mm x 0.9 mm DFN package 1 A dc-dc with integrated inductor; 5 mm x 4 mm x 1.1 mm package 1 A dc-dc regulator; tiny 3 mm x 2 mm x 0.9 mm DFN package 3 A dc-dc with integrated inductor; 10 mm x 7.5 mm x 1.85 mm QFN package 3-Pin VID VOUT programming 3 A dc-dc with integrated inductor; 10 mm x 7.5 mm x 1.85 mm QFN package External resistor divider VOUT programming 6 A dc-dc with integrated inductor; 12 mm x 10 mm x 1.85 mm QFN package 3-Pin VID VOUT programming; Parallel capable 6 A dc-dc with integrated inductor; 12 mm x 10 mm x 1.85 mm QFN package External resistor divider VOUT programming; Parallel capable Contact Information Enpirion, Inc. 685 Route 202/206 Suite 305 Bridgewater, NJ 08807 Phone: 908-575-7550 Fax: 908-575-0775 Enpirion reserves the right to make changes in circuit design and/or specifications at any time without notice. Information furnished by Enpirion is believed to be accurate and reliable. Enpirion assumes no responsibility for its use or for infringement of patents or other third party rights, which may result from its use. Enpirion products are not authorized for use in nuclear control systems, as critical components in life support systems or equipment used in hazardous environment without the express written authority from Enpirion.. ©Enpirion 2007 all rights reserved, E&OE 15 www.enpirion.com