Copyright
ANPEC Electronics Corp.
Rev. A.6 - Apr , 2005
APW7037/A/B
www.anpec.com.tw
1
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.
8-PIN Synchronous Buck PWM Controller
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
2% Output Voltage Accuracy Over Temperature
Under-Voltage Protection for Output
200/400kHz Constant Frequency Operation
-200kHz for APW7037 & APW7037B
-400kHz for APW7037A
Small size, 8-PIN Package (SOIC or TSSOP)
Lead Free Available (RoHS Compliant)
Features
Applications
Graphics Cards
DDR Memory Power Supply
DDR Memory Termination Voltage
Low-Voltage Distributed Power Supplies
General Description
The APW7037 series are designed to provide a low
cost synchronous Buck regulator for on-board DC to
DC converter applications. The APW7037 series to-
gether with dual N-channel MOSFETs such as
APM7313, provide a low cost solution for such
applications. Each device features an internal 200/
400kHz oscillator, Power-On-Reset (POR) for both VCC
and VC supplies, an external programmable soft-start
function as well as output under-voltage detection that
latches off the device when an output short is detected.
Pin Description
1
2
3
4
5
6
7
8
FB
VCC
LDRV
GND
HDRV
VC
COMP
SS
Copyright
ANPEC Electronics Corp.
Rev. A.6 - Apr, 2005
APW7037/A/B
www.anpec.com.tw
2
Absolute Maximum Ratings
Block Diagram
V CC
V CC
V C
HDRV
LDRV
OSC
Gate
Control
V
R EF
S S
20uA
3.3V
G ND
F
OSC
CO M P
Error
A mp.
F B
PW M
25k
25k
V
F BU V
Under-V oltage
Regulator
4.5V
Max .
64uA
POR
Pow er
On Res et
Description
Rating
Unit
VCC to GND
-0.2~30
V
VC to GND
-0.2~30
V
Operating Junction Temperature
0~125
C
Storage Tem perature
-65~150
C
Soldering Temperature (10 Seconds)
300
C
Minim um ESD Rating
2
kV
Ordering and Marking Information
APW 7037/A/B
Handling Code
Temp. Range
Package Code
Package Code
K : SO-8 R : TSSOP-8
Operating Junction Temp. Range
C : 0 to 70C
Handling Code
TU : Tube
TR : Tape & Reel
Lead Free Code
L : Lead Free Device Blank : Original Device
APW 7037/A/B K :
APW 7037/A/B
XXXXX
XXXXX - Date Code
APW 7037/A/B R :
APW 7037/A/B
XXXXX
XXXXX - Date Code
Lead Free Code
Notes: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte in plate termi-
nation finish; which are fully compliant with RoHS and compatible with both SnPb and lead-free soldiering operations.
ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J STD-020C for MSL classifica-
tion at lead-free peak reflow temperature.
Copyright
ANPEC Electronics Corp.
Rev. A.6 - Apr, 2005
APW7037/A/B
www.anpec.com.tw
3
Electrical Characteristics
Unless otherwise specified, these specifications apply over VCC=5V, VC=12V and T
A
=0 to 70
C. Typical
values refer to T
A
=25
.
APW7037/A/B Unit
Symbol Parameter
Test
Conditions Min. Typ. Max.
SUPPLY CURRENT
I
CC
VCC Dynamic Supply
Current
F
OSC
=200KHz, C
L
=1500pF
2 3 5
mA
I
C
VC Dynamic Supply Current F
OSC
=200KHz, C
L
=1500pF
2 5.5 8 mA
I
CCQ
VCC Static Supply Current
SS=GND
0.5 1.5 3 mA
I
CQ
VC Static Supply Current
SS=GND
0.2 0.4 1 mA
POWER-ON RESET
Rising VCC Threshold
4.0
4.2
4.4
V
VCC POR Hysteresis
0.25
V
Rising VC Threshold
3.1
3.3
3.5
V
VC POR Hysteresis
0.2
V
OSCILLATOR
F
OSC
Free Running Frequency
APW7037
APW7037A
APW7037B
180
360
180
200
400
200
220
440
220
KHz
V
OSC
Ramp Amplitude
1.10
V
ERROR AMPLIFIER
I
FB1
FB Pin Input Bias Current
SS=3V, V
FB
=1V
1
nA
I
FB2
FB Pin Input Bias Current
SS=0V, V
FB
=1V
-64
A
GM Transconductance
450 600 750
mho
REFERENCE VOLTAGE
V
FB
FB Pin Regulation Voltage
APW7037
APW7037A
APW7037B
1.225
0. 784
0.784
1.250
0. 800
0.800
1.275
0. 816
0.816
V
LREG V
FB
Line Regulation
VCC = 5~12V
0.2 0.35
%
Thermal Characteristics
Symbol
Parameter
Value
Unit
JA
Thermal Resistance in Free Air
8-pin SOIC
8-pin TSSOP
160
124
C/W
Copyright
ANPEC Electronics Corp.
Rev. A.6 - Apr, 2005
APW7037/A/B
www.anpec.com.tw
4
1+
R
O U T
R
G N D
(
)
Functional Pin Description
FB (Pin 1)
Connect this pin to the output (V
OUT
) of the PWM con-
verter via an external resistor divider to provide a volt-
age feedback path for the converter. The output volt-
age set by the resistor divider is determined using the
following formula :
V
OUT
= V
REF
x
where R
OUT
is the resistor connected from V
OUT
to FB
, and R
GND
is the resistor connected from FB to ground.
The voltage at this pin is also monitored for Under-
Voltage 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 capabil-
ity 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
external resistor-capacitor network to provide a loop
compensation for the PWM converter.
SS (Pin 8)
Connect a capacitor from this pin to ground.This
capacitor, along with an internal 20uA current source,
sets the soft-start interval of the PWM converter and
prevents the outputs from overshoot as well as limits
the input current. Pull this pin below 0.5V can shut-
down the converter.
Electrical Characteristics (Cont.)
Unless otherwise specified, these specifications apply over VCC=5V, VC=12V and T
A
=0 to 70
C. Typical
values refer to T
A
=25
C.
APW7037/A/B Unit
Symbol Parameter
Test
Conditions Min. Typ. Max.
GATE DRIVERS
HDRV Rising Time
C
L
= 1500pF
20
50
nS
HDRV Falling Time
C
L
= 1500pF
15
50
nS
LDRV
Rising
Time
C
L
= 1500pF
25
50
nS
LDRV
Falling
Time
C
L
= 1500pF
25
50
nS
Dead Band Time
50
150
250
nS
PROTECTION
V
FBUV
FB Under-Voltage Threshold V
FB
Falling APW7037
APW7037A
APW7037B
0.4
0.3
0.3
0.6
0. 4
0.4
0.8
0. 5
0.5
V
V
SD
Shutdown Threshold Voltage Pull the voltage of SS pin
0.5
V
I
SS
Soft-Start Current
SS=0
10
20
30
A
Copyright
ANPEC Electronics Corp.
Rev. A.6 - Apr, 2005
APW7037/A/B
www.anpec.com.tw
5
Typical Applications
1. Dual supply voltage(5V and 12V) application
2. Single supply voltage(5V) application
V
IN
+ 5V
V
OU T
1.5V /5 A
C7
0.1uF
C5
1uF
C4
100uF
C3
47uF
C6,C9
2 x 150uF
R1
249
R2
1.24k
Q 1A
A P M 7313
L3
1uH
H D R V
5
L D R V
3
V C
6
F B
1
V C C
2
G N D
4
S S
8
C O M P
7
C8
2200pF
R3
24k
Q 1B
A P M 7313
C1
1uF
L4
3.3uH
U1
A P W 7037
C2
1uF
+ 12V
Q 2
A P M 2300A
Shutdown
R4
3
V
IN
+ 5V
V
OU T
1.5V /5 A
C8
0.1uF
C3
0.1uF
C6
1uF
C5
100uF
C4
47uF
C7,C10
2 x 150uF
R1
249
R2
1.24k
Q1A
A P M 7312
L3
1uH
H DR V
5
LD RV
3
V C
6
FB
1
V CC
2
G N D
4
S S
8
C O M P
7
C9
2200pF
R3
24k
Q1B
A P M 7312
C1
1uF
D1
1N4148
L4
3.3uH
U1
A P W 7037
D2
1N4148
C2
1uF
Q2
A P M 2300A
Shutdown
R4
3
D3
1N4148
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