APW7037A/B
8-PIN Synchronous Buck PWM Controller
Features
•
•
•
Operating with Single 5V or 12V Input
Drives N-Channel MOSFETs
Simple Single-Loop Control Design
- Voltage-Mode PWM Control
- Full 0% to 100% Duty Ratio
- Fast Transient Response
General Description
The APW7037 series are designed to provide a low cost
synchronous Buck regulator for on-board DC to DC con-
verter applications. The APW7037 series together with
dual N-channel MOSFETs such as APM7313, provide a
low cost solution for such applications. Each device fea-
tures an internal 200/400kHz oscillator, Power-On-Reset
(POR) for both VCC and VC supplies, an external pro-
grammable soft-start function as well as output under-
voltage detection that latches off the device when an out-
put short is detected.
•
•
•
±2% Output Voltage Accuracy Over Temperature
Under-Voltage Protection for Output
200/400kHz Constant Frequency Operation
- 200kHz for APW7037B
- 400kHz for APW7037A
•
•
Small size, 8-PIN Package (SOIC or TSSOP)
Lead Free and Green Devices Available
(RoHS Compliant)
Pin Configuration
FB
1
2
3
4
8
7
6
5
SS
COMP
VC
HDRV
Applications
•
•
•
•
Graphics Cards
DDR Memory Power Supply
DDR Memory Termination Voltage
Low-Voltage Distributed Power Supplies
VCC
LDRV
GND
ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise
customers to obtain the latest version of relevant information to verify before placing orders.
Copyright
©
ANPEC Electronics Corp.
Rev. A.7 - Jun. , 2008
1
www.anpec.com.tw
APW7037A/B
Ordering and Marking Information
APW7037A/B
Assembly Material
Handling Code
Temperature Range
Package Code
APW7037A/B
XXXXX
APW7037A/B
XXXXX
Package Code
K : SOP-8
O : TSSOP-8
Operating Junction Temperature Range
C : 0 to 70
o
C
Handling Code
TR : Tape & Reel
Assembly Material
L : Lead Free Device
G : Halogen and Lead Free Device
XXXXX - Date Code
APW7037A/B K :
APW7037A/B O :
XXXXX - Date Code
Note : ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish;
which are fully compliant with RoHS. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J-STD-
020C for MSL classification at lead-free peak reflow temperature. ANPEC defines “Green” to mean lead-free (RoHS compliant) and
halogen free (Br or Cl does not exceed 900ppm by weight in homogeneous material and total of Br and Cl does not exceed
1500ppm by weight).
Absolute Maximum Ratings
Symbol
V
CC
V
C
T
J
T
STG
T
SDR
VCC to GND
VC to GND
Operating Junction Temperature
Storage Temperature
Maximum Lead Soldering Temperature, 10 Seconds
Parameter
Rating
-0.2~30
-0.2~30
0~125
-65~150
260
Unit
V
V
°C
°C
°C
Thermal Characteristics
Symbol
θ
JA
Thermal Resistance in Free Air
SOP-8
TSSOP-8
160
124
Parameter
Typical Value
Unit
°C/W
Copyright
©
ANPEC Electronics Corp.
Rev. A.7 - Jun., 2008
2
www.anpec.com.tw
APW7037A/B
Electrical Characteristics
Unless otherwise specified, these specifications apply over V
CC
=5V, V
C
=12V and T
A
=0 to 70°C. Typical values refer to T
A
=25°C.
APW7037/A/B
Symbol
SUPPLY CURRENT
ICC
IC
ICCQ
ICQ
VCC Dynamic Supply
Current
VC Dynamic Supply Current
VCC Static Supply Current
VC Static Supply Current
FOSC=200kHz, CL=1500pF
FOSC=200kHz, CL=1500pF
SS=GND
SS=GND
2
2
0.5
0.2
3
5.5
1.5
0.4
5
8
3
1
mA
mA
mA
mA
Parameter
Test Conditions
Unit
Min.
Typ.
Max.
POWER-ON-RESET
Rising VCC Threshold
VCC POR Hysteresis
Rising VC Threshold
VC POR Hysteresis
OSCILLATOR
FOSC
∆V
OSC
IFB1
IFB2
GM
Free Running Frequency
Ramp Amplitude
APW7037A
APW7037B
360
180
-
400
200
1.10
440
220
-
kHz
V
4.0
-
3.1
-
4.2
0.25
3.3
0.2
4.4
-
3.5
-
V
V
V
V
ERROR AMPLIFIER
FB Pin Input Bias Current
FB Pin Input Bias Current
Transconductance
SS=3V, VFB=1V
SS=0V, VFB=1V
-
-
450
1
-64
600
-
-
750
nA
µA
µmho
REFERENCE VOLTAGE
VFB
LREG
FB Pin Regulation Voltage
VFB Line Regulation
VCC = 5~12V
APW7037A
APW7037B
0. 784
0.784
-
0. 800
0.800
0.2
0. 816
0.816
0.35
V
%
GATE DRIVERS
HDRV Rising Time
HDRV Falling Time
LDRV Rising Time
LDRV Falling Time
Dead Band Time
PROTECTION
VFBUV
FB Under-Voltage Threshold
VFB Falling
APW7037A
APW7037B
VSD
ISS
Shutdown Threshold Voltage
Soft-Start Current
Pull the voltage of SS pin
SS=0
0.3
0.3
-
10
0.4
0.4
0.5
20
0.5
0.5
-
30
V
µA
V
CL = 1500pF
CL = 1500pF
CL = 1500pF
CL = 1500pF
-
-
-
-
50
20
15
25
25
150
50
50
50
50
250
nS
nS
nS
nS
nS
Copyright
©
ANPEC Electronics Corp.
Rev. A.7 - Jun., 2008
3
www.anpec.com.tw
APW7037A/B
Function Pin Description
FB (Pin 1)
Connect this pin to the output (VOUT) of the PWM con-
verter via an external resistor divider to provide a voltage
feedback path for the converter. The output voltage set by
the resistor divider is determined using the following for-
mula :
SS (Pin 8)
Connect a capacitor from this pin to ground.This capacitor,
along with an internal 20µA current source, sets the soft-
start interval of the PWM converter and prevents the out-
puts from overshoot as well as limits the input current.
Pull this pin below 0.5V can shutdown the converter.
V
OUT
= V
REF
x
( 1+
R
OUT
)
R
GND
where ROUT is the resistor connected from VOUT to FB
, and RGND is the resistor connected from FB to ground.
The voltage at this pin is also monitored for Under-Volt-
age protection.
VCC (Pin 2)
Connect this pin to input voltage from 5V to 20V. This pin
provides the bias for the control circuitry and the low-side
power MOSFET driver (LDRV). The voltage at this pin is
monitored for Power-On-Reset (POR) purpose.
LDRV (Pin 3)
Connect this pin to the gate of the low-side power
MOSFET. This pin provides the gate drive for the MOSFET.
GND (Pin 4)
Signal and power ground for the IC. All voltage levels are
measured with respect to this pin.
HDRV (Pin 5)
Connect this pin to the gate of the high-side power
MOSFET. This pin provides the gate drive for the
MOSFET.
VC (Pin 6)
This pin provides bias voltage to the high-side MOSFET
driver. A bootstrap circuit may be used to pump a boot
voltage for enforcing the driving capability of the gate driver
and improving the performance of the MOSFET.
COMP (Pin 7)
This pin is the output of the error amplifier. Add an exter-
nal resistor-capacitor network to provide a loop compen-
sation for the PWM converter.
Copyright
©
ANPEC Electronics Corp.
Rev. A.7 - Jun., 2008
4
www.anpec.com.tw
APW7037A/B
Block Diagram
SS
20uA
4.5V
3.3V
Max .
64uA
POR
Pow er
On Reset
Regulator
VCC
VC
HDRV
Under-Voltage
V
FBUV
25k
Gate
Control
V CC
FB
25k
V
REF
Error
Amp.
OSC
F
OSC
PWM
LDRV
COMP
GND
Typical Application Circuit
1. Dual supply voltage(5V and 12V) application
R4
3
C1
1uF
VCC
2
+12V
C2
1uF
VC
C5
1uF
L3
C4
1uH
100uF
C3
47uF
V
IN
+5V
6
Q2
APM2300
A
C7
0.1uF
8
SS
U1
APW7037A/B
7
HDRV
5
Q1A
APM7313
Q1B
APM7313
L4
3.3uH
V
OUT
1.5V/5 A
C6,C9
2 x 150uF
R1
249
R2
1.24k
Shutdown
3
COMP
LDRV
R3
24k
GND
FB
1
C8
2200pF
4
Copyright
©
ANPEC Electronics Corp.
Rev. A.7 - Jun., 2008
5
www.anpec.com.tw
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