APW7120
5V to 12V Supply Voltage, 8-PIN, Synchronous Buck PWM Controller
Features
•
•
•
Operating with Single 5~12V Supply Voltage
or Two Supply Voltages
Drive Dual Low Cost N-Channel MOSFETs
- Adaptive Shoot-Through Protection
Built-in Feedback Compensation
- Voltage-Mode PWM Control
- 0~100% Duty Ratio
- Fast Transient Response
General Description
The APW7120 is a fixed 300kHz frequency, voltage
mode, and synchronous PWM controller. The device
drives two low cost N-channel MOSFETs and is de-
signed to work with single 5~12V or two supply
voltage(s), providing excellent regulation for load
transients.
The APW7120 integrates controls, monitoring, and
protection functions into a single 8-pin package to
provide a low cost and perfect power solution.
A power-on-reset (POR) circuit monitors the VCC
supply voltage to prevent wrong logic controls. An
internal 0.8V reference provides low output voltage
down to 0.8V for further applications. An built-in digital
soft-start with fixed soft-start interval prevents the
output voltage from overshoot as well as limits the
input current. The controller’s over-current protection
monitors the output current by using the voltage drop
across the low-side MOSFET’s R
DS(ON)
, eliminating the
need of a current sensing resistor. Additional under
voltage and over voltage protections monitor the
voltage on FB pin for short-circuit and over-voltage
protections. The over-current protection cycles the
soft-start function until 4 over-current events are
counted.
Pulling and holding the voltage on OCSET pin below
0.15V with an open drain device shuts down the
controller.
•
±2%
0.8V Reference
- Over Line, Load Regulation, and Operating
Temperature
•
•
•
•
•
Programmable Over-Current Protection
- Using R
DS(ON)
of Low-Side MOSFET
Hiccup-Mode Under-Voltage Protection
118% Over-Voltage Protection
Adjustable Output Voltage
Small Converter Size
- 300kHz Constant Switching Frequency
- Small SOP-8 Package
•
•
•
Built-In Digital Soft-Start
Shutdown Control Using an External MOSFET
Lead Free and Green Devices Available
(RoHS Compliant)
Applications
•
•
•
Motherboard
Graphics Card
High Current, up to 20A, DC-DC Converters
Pin Configuration
BOOT 1
UGATE 2
GND 3
LGATE 4
8 PHASE
7 OCSET
6 FB
5 VCC
SOP-8
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.5 - Jun., 2008
1
www.anpec.com.tw
APW7120
Ordering and Marking Information
APW7120
Assembly Material
Handling Code
Temperature Range
Package Code
APW7120 K :
APW7120
XXXXX
Package Code
K : SOP-8
Operating Ambient Temperature Range
E : -20 to 70
°
C
Handling Code
TR : Tape & Reel
Assembly Material
L : Lead Free Device
G : Halogen and Lead Free Device
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
BOOT
(Note 1)
Rating
-0.3 ~ 16
-0.3 ~ 16
-5 ~ V
BOOT
+0.3
-0.3 ~ V
BOOT
+0.3
-5 ~ V
CC
+0.3
-0.3 ~ V
CC
+0.3
-10 ~ 30
-3 ~ 16
-0.3 ~ 7
150
-65 ~ 150
260
Unit
V
V
V
Parameter
VCC Supply Voltage (VCC to GND)
BOOT Voltage (BOOT to PHASE)
UGATE Voltage (UGATE to PHASE)
<400ns pulse width
>400ns pulse width
LGATE Voltage (LGATE to GND)
<400ns pulse width
>400ns pulse width
PHASE Voltage (PHASE to GND)
<400ns pulse width
>400ns pulse width
V
V
V
o
o
o
V
I/O
Input Voltage (OCSET, FB to GND)
Maximum Junction Temperature
C
C
C
T
STG
T
SDR
Storage Temperature
Maximum Lead Soldering Temperature, 10 Seconds
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Thermal Characteristics
Symbol
θ
JA
Parameter
Junction-to-Ambient Resistance in free air
(Note 2)
Typical Value
160
Unit
o
C/W
Note 2:
θ
JA
is measured with the component mounted on a high effective thermal conductivity test board in free air.
Copyright
©
ANPEC Electronics Corp.
Rev. A.5 - Jun., 2008
2
www.anpec.com.tw
APW7120
Recommended Operating Conditions
Symbol
V
CC
V
OUT
V
IN
I
OUT
T
A
T
J
Parameter
VCC Supply Voltage
Converter Output Voltage
Converter Input Voltage
Converter Output Current
Ambient Temperature
Junction Temperature
(Note 3)
Range
4.5 ~ 13.2
0.8 ~ 80%V
IN
2.2 ~ 13.2
0 ~ 20
-20 ~ 70
-20 ~ 125
Unit
V
V
V
A
o
o
C
C
Note 3: Please refer to the typical application circuit.
Electrical Characteristics
Unless otherswise specified, these specifications apply over V
CC
= 12V, V
BOOT
= 12V and T
A
= -20 ~ 70
o
C.
Typical values are at T
A
= 25
o
C.
Symbol
SUPPLY CURRENT
I
VCC
VCC Nominal Supply Current
VCC Shutdown Supply Current
POWER-ON-RESET
Rising VCC Threshold
Hysteresis
OSCILLATOR
F
OSC
∆V
OSC
V
REF
Free Running Frequency
Ramp Amplitude
Reference Voltage
Accuracy
Line Regulation
ERROR AMPLIFIER
DC Gain
F
P1
F
Z
F
P2
First Pole Frequency
Zero Frequency
Second Pole Frequency
Average UGATE Duty Range
FB Input Current
Copyright
©
ANPEC Electronics Corp.
Rev. A.5 - Jun., 2008
3
Parameter
Test Conditions
APW7120
Min.
-
-
3.8
0.1
250
-
Typ. Max.
2.1
1.5
4.1
0.45
300
1.5
0.8
-
-
0.05
86
0.4
0.4
430
-
-
6
4
4.4
0.6
350
-
-
+0.75
+1.5
+0.3
-
-
-
-
85
0.1
Unit
UGATE and LGATE Open
mA
mA
V
V
kHz
V
P-P
V
%
%
dB
Hz
kHz
kHz
%
µA
REFERENCE VOLTAGE
Measured at FB Pin
T
A
=25°C
T
A
=-20~70°C, V
CC
=5V ~ 12V
V
CC
=5V ~ 12V
-
-0.75
-1.5
-
-
-
-
-
0
-
www.anpec.com.tw
APW7120
Electrical Characteristics (Cont.)
Unless otherswise specified, these specifications apply over V
CC
= 12V, V
BOOT
= 12V and T
A
= -20 ~ 70
o
C.
Typical values are at T
A
= 25
o
C.
Symbol
Parameter
Test Conditions
APW7120
Min.
1.0
-
1.0
-
-
35
0.37
62
-
114
2
Typ.
2.0
3.5
1.9
2.6
40
40
0.4
67
45
118
3.8
0.15
40
Max.
-
7
-
5
100
45
0.43
72
-
122
5
0.3
-
Unit
PWM CONTROLLER GATE DRIVERS
UGATE Source
UGATE Sink
LGATE Source
LGATE Sink
T
D
Dead-Time
PROTECTIONS
I
OCSET
OCSET Current Source
U
VFB
Over-Current Reference
Voltage
FB Under-Voltage Threshold
FB Under-Voltage Hysteresis
Over-Voltage Threshold
SOFT-START AND SHUTDOWN
T
SS
Soft-Start Interval
OCSET Shutdown Threshold
OCSET Shutdown Hysteresis
Falling V
OCSET
ms
V
mV
0.1
-
V
FB
Rising
V
PHASE
=0V, Normal Operation
T
A
=-20~70°C
V
FB
Falling
µA
V
%
mV
%
V
BOOT-PHASE
=12V, V
UGATE-PHASE
=6V
V
BOOT-PHASE
=12V, V
UGATE-PHASE
=1V
V
CC
=12V, V
LGATE
=6V
V
CC
=12V, V
LGATE
=1V
Guaranteed by Design
A
Ω
A
Ω
ns
Copyright
©
ANPEC Electronics Corp.
Rev. A.5 - Jun., 2008
4
www.anpec.com.tw
APW7120
Function Pin Description
BOOT (Pin 1)
This pin provides ground referenced bias voltage to
the high-side MOSFET driver. A bootstrap circuit with
a diode connected to 5~12V is used to create a
voltage suitable to drive a logic-level N-channel
MOSFET.
UGATE (Pin 2)
Connect this pin to the high-side N-channel MOSFET’s
gate. This pin provides gate drive for the high-side
MOSFET.
GND (Pin 3)
The GND terminal provides return path for the IC’s bias
current and the low-side MOSFET driver’s pull-low
current. Connect the pin to the system ground via very
low impedance layout on PCBs.
LGATE (Pin 4)
Connect this pin to the low-side N-channel MOSFET’s
gate. This pin provides gate drive for the low-side
MOSFET.
VCC (Pin 5)
Connect this pin to a 5~12V supply voltage. This pin
provides bias supply for the control circuitry and the
low-side MOSFET driver. The voltage at this pin is
monitored for the Power-On-Reset (POR) purpose.
FB (Pin 6)
This pin is the inverting input of the internal Gm amplifier.
Connect this pin to the output (V
OUT
) of the converter
via an external resistor divider for closed-loop operation.
The output voltage set by the resistor divider is deter-
mined using the following formula :
V
OUT
=
0.8V
⋅
( 1
+
R1
)
R2
(V)
where R1 is the resistor connected from V
OUT
to FB ,
and R2 is the resistor connected from FB to GND. The
FB pin is also monitored for under and over-voltage
events.
OCSET (Pin 7)
The OCSET is a dual-function input pin for over-
current protection and shutdown control. Connect a
resistor (R
OCSET
) from this pin to the Drain of the low-
side MOSFET. This resistor, an internal 40µA current
source (I
OCSET
), and the MOSFET’s on-resistance
(R
DSON
) set the converter over-current trip level (I
PEAK
)
according to the following formula:
I
PEAK
=
40
μ
A
⋅
R
OCSET
- 0.4V
R
DSON
(A)
Pulling and holding this pin below 0.15V with an open
drain device, with very low parasitic capacitor, shuts
down the IC with floating output and also resets the
over-current counter. Releasing OCSET pin initiates a
new soft-start and the converter works again.
PHASE (Pin 8)
The pin provides return path for the high-side MOSFET
driver’s pull-low current. Connect this pin to the high-
side MOSFET’s source.
Copyright
©
ANPEC Electronics Corp.
Rev. A.5 - Jun., 2008
5
www.anpec.com.tw
