Advanced
Monolithic
Systems
AMS34063
DC-TO-DC CONVERTER CONTROL CIRCUIT
FEATURES
APPLICATIONS
• Wide Input Voltage Operating Range from 2.5V to 40V
• Low Standby Current
• Current Limiting
• Output Switch Current of 1.5A
• Output Voltage Adjustable from 1.25 to 40V
• Frequency of Operation to 100kHz
• Step-Up Converter
• Step-Down Converter
• Voltage Inverting Application
GENERAL DESCRIPTION
The AMS34063 series is a control circuit containing the basic functions required for DC-to-DC converters. The device consists
of an internal temperature compensated reference, a comparator, a controlled duty cycle oscillator with an active current limit
circuit, a driver and a high current output switch. Designed specifically to be incorporated in Step-Up, Step-Down and Voltage
-Inverting applications, the AMS34063 requires a minimum number of external components.
The AMS34063 is available in the 8-lead plastic SOIC and 8-lead plastic DIP packages.
ORDERING INFORMATION
PACKAGE TYPE
8 LEAD PDIP
AMS34063P
OPER. TEMP
8 LEAD SOIC
AMS34063S
RANGE
-40°C to +85°C
PIN CONNECTIONS
8 LEAD SOIC/ 8 LEAD PDIP
SWITCH
COLLECTOR
SWITCH
EMITTER
TIMING
CAPACITOR
GND
DRIVER
COLLECTOR
IPK SENSE
1
8
2
7
3
6 VCC
4
5 COMPARATOR
INVERTING
INPUT
Top View
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AMS34063
ABSOLUTE MAXIMUM RATINGS (Note 1)
Power Supply Voltage, VCC
40V
Comparator Input Voltage Range, VIR
-0.3V to +40V
Switch Collector Voltage, VC(switch)
40V
Switch Emitter Voltage, VE(switch)
40V
Switch Collector to Emitter Voltage, VCE(switch)
40V
Driver Collector Voltage, VC(driver)
Switch Current, ISW
Power Dissipation
Maximum Junction Temperature
Storage Temperature
40V
1.5A
(Note 3)
+125°C
-65°C to +150°C
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at VCC = 5.0V, -40°C ≤TA ≤+85°C, unless otherwise noted.
PARAMETER
Min.
AMS34063
Typ.
Max.
CONDITIONS
Units
Oscillator
Charging Current
5.0V ≤ VCC ≤ 40V, TA= 25°C
20
35
50
µA
Discharge Current
5.0V ≤ VCC ≤ 40V, TA= 25°C
150
200
250
µA
Voltage Swing
TA= 25°C
0.5
VP-P
Discharge to Charge Current
Ratio
IPK(sense) = VCC, TA= 25°C
6.0
_
Current Limit Sense Voltage
ICHG = IDISCHG, TA= 25°C
250
300
350
mV
Output Switch (Note 2)
Saturation Voltage, Darlington
Connection
ISW = 1.0A, VC(driver) = VC(switch)
1.0
1.3
V
Saturation Voltage
ISW = 1.0A, IC(driver) = 50mA, (Forced β ≈ 20)
0.45
0.7
V
DC Current Gain
ISW = 1.0A, VCE = 5.0V, TA= 25°C
35
120
Collector Off-State Current
VCE = 40V, TA= 25°C
10
nA
Comparator
Threshold Voltage
1.18
Threshold Voltage Line
Regulation
3.0V ≤ VCC ≤ 40V
Input Bias Current
VIN = 0V
1.25
1.32
V
0.04
0.2
mV/V
40
400
nA
Total Device
5.0V ≤ VCC ≤ 40V, IPK(sense) = VCC ,
2.4
3.5
mA
CT = 0.001µF, V pin 5 > Vth,
Pin 2 = Gnd, Remaining pins open
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. For guaranteed performance limits and associated test
conditions, see the Electrical Characteristics tables.
Note 2: To minimize power dissipation, low duty cycle pulse testing is used.
Note 3: Power dissipation at TA = 25°C is equal to 1.0W for the 8 lead P DIP package and 625mW for the SO-8 package. For operation at temperatures above
TA = 25°C derate the power dissipation at 10mW/°C.
Supply Current
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AMS34063
FUNCTIONAL BLOCK DIAGRAM
1
8
DRIVE
COLLECTOR
S
Q
SWITCH
COLLECTOR
Q2
Q1
R
170
7
IPK SENSE
IPK
OSC
VCC
SWITCH
EMITTER
3
TIMING
CAPACITOR
CT
6
+
COMP.
-
COMPARATOR
INVERTING
INPUT
2
1.25V
REF
REG
5
4
GND
TYPICAL PERFORMANCE CHARACTERISTICS
Standby Supply Current vs
Supply Voltage
1000
3.2
VCC = 5.0V
IPK(sense) = VCC
Pin 5 = GND
SUPPLY CURRENT (mA)
OUTPUT SWITCH ON-OFF TIME (µs)
Output Switch On-Off Time vs
Oscillator Timing Capacitor
100
10
1.0
CT= 0.001µF
IPK(sense) = VCC
Pin 2 = GND
2.4
1.6
0.8
0
100
0.1
1.0
10
OSCILLATOR TIMING CAPACITOR
0
Common-Emitter Configuration
Output Switch Saturation Voltage
vs Collector Current
Emitter-Follower Configuration
Output Switch Saturation Voltage
vs Emitter Current
1.6
1.2
VCC = 5.0V
Pins 1,7,8 = VCC
Pin 3,5 = GND
1.5
SATURATION VOLTAGE (V)
SATURATION VOLTAGE (V)
5.0 10 15 20 25 30 35 40
SUPPLY VOLTAGE (V)
1.4
1.3
1.2
1.1
VCC = 5.0V
Pin 7 = VCC
Pin 2,3,5 = GND
1.0
Darlington Connection
0.8
0.6
Forced Beta ≈20
0.4
0.2
1.0
0
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
EMITTER CURRENT (A)
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0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
COLLECTOR CURRENT (A)
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AMS34063
TYPICAL APPLICATIONS
Step-Down Converter
1
8
S
Q
Q2
R
Q1
2
7
IPK
RSC
0.33
VIN
25V
OSC
CT
1N5822
3
6
CT
470
pF
+
100
µF
+
COMP.
-
1.25V
REF
REG
5
L
220µH
4
R2
R1
1.2 k
470
µF
3.6 k
Test
+
CO
VOUT
5.0V/500mA
Conditions
Results
Line Regulation
VIN = 15 to 25V, IO = 500mA
15mV
Load Regulation
VIN = 25V, IO = 50 to 500mA
5.0mV
Output Ripple
VIN = 25V, IO = 500mA
40 mVP-P
Short Circuit Current
VIN = 25V, RL = 0.1Ω
2.3A
Efficiency
VIN = 25V, IO = 500mA
84.7%
External Current Boost Connections for IC Peak Greater than 1.5A
a. External NPN Switch
8
b. External PNP Saturated Switch
1
1
8
VOUT
7
2
7
2
VOUT
RSC
RSC
VIN
6
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VIN
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AMS34063
TYPICAL APPLICATIONS (Continued)
Step-Up Converter
170µH
L
1
8
180
S
Q
Q2
R
Q1
7
2
IPK
RSC
0.22
VIN
12V
OSC
CT
1N5819
6
100
µF
3
+
+
COMP.
-
1.25V
REF
REG
5
CT
1500
pF
4
R2
R1
2.2 k
150
µF
47 k
Test
+
CO
VOUT
28V/175mA
Conditions
Results
Line Regulation
VIN = 8 to 16V, IO = 175 mA
12 mV
Load Regulation
VIN = 12V, IO = 75 to 175 mA
5.0 mV
Output Ripple
VIN = 12V, IO = 175 mA
40 mVP-P
Short Circuit Current
VIN = 12V, RL = 0.1Ω
2.3A
Efficiency
VIN = 12V, IO = 175 mA
84.7%
External Current Boost Connections for IC Peak Greater than 1.5A
a. External NPN Switch
18
0
8
7
b. External NPN Saturated Switch
1
VOUT
2
RSC
VIN
8
1
7
2
VOUT
180
RSC
6
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VIN
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R 0 for
constant VIN
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AMS34063
APPLICATION HINTS
Design Formula Table
Calculation
Step-Down
Step-Up
tON
tOFF
VOUT + VF
VIN(MIN) - VSAT - VOUT
VOUT + VF - VIN(MIN)
VIN(MIN) - VSAT
(tON + tOFF) MAX
1
fMIN
1
fMIN
CT
4 x 10-5tON
4 x 10-5tON
IPK(switch)
2IOUT(MAX)
 tON + tOFF 
2IOUT ( MAX )

 tOFF 
RSC
0.33/IPK(switch)
0.33/IPK(switch)
 VIN(MIN) − VSAT − VOUT 

 tON(MAX )
IPK(switch)


IPK(switch) (tON + tOFF)
8Vripple(P − P)
 VIN(MIN) − VSAT 

tON(MAX )
IPK(switch)


IOUT tON
≈
Vripple
L(MIN)
CO
VSAT = Saturation voltage of the output switch.
VF = Forward voltage drop of the ringback rectifier.
Notes
The following power supply characteristics must be chosen:
VIN – Nominal input voltage. If this voltage is not constant, then use VIN(MAX) for step-down and VIN(MIN) for step-up converter.
 R2 
VOUT – Desired output voltage, VOUT = 1.25 1 +
.
R1 

IOUT - Desired output current.
fMIN - Minimum desired output switching frequency at the selected values for VIN and IO.
Vripple(P-P) – Desired peak-to-peak output ripple voltage. In practice, the calculated value will need to be increased due to the
capacitor’s equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it will
directly effect the line and load regulation.
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS34063
PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.
8 LEAD SOIC PLASTIC PACKAGE (S)
0.189-0.197*
(4.801-5.004)
8
7
6
5
0.228-0.244
(5.791-6.197)
0.150-0.157**
(3.810-3.988)
1
2
3
4
0.010-0.020
x 45°
(0.254-0.508)
0.053-0.069
(1.346-1.752)
0.004-0.010
(0.101-0.254)
0.014-0.019
(0.355-0.483)
0.008-0.010
(0.203-0.254)
0.050
(1.270)
TYP
0°-8° TYP
0.016-0.050
(0.406-1.270)
S (SO-8 ) AMS DRW# 042293
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
8 LEAD PLASTIC DIP PACKAGE (P)
0.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
0.255±0.015*
(6.477±0.381)
0.045-0.065
(1.143-1.651)
0.300-0.325
(7.620-8.255)
0.130±0.005
(3.302±0.127)
0.065
(1.651)
TYP
0.005
(0.127)
MIN
0.100±0.010
(2.540±0.254)
0.125
(3.175)
MIN
0.009-0.015
(0.229-0.381)
0.015
(0.380)
MIN
0.018±0.003
(0.457±0.076)
0.325 +0.025
-0.015
(8.255 +0.635
-0.381
)
P (8L PDIP ) AMS DRW# 042294
*DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTUSIONS.
MOLD FLASH OR PROTUSIONS SHALL NOT EXCEED 0.010" (0.254mm)
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723