UNISONIC TECHNOLOGIES CO., LTD
SR2803
330KHZ, 3A SYNCHRONOUS
BUCK CONTROLLER
DESCRIPTION
The UTC
SR2803
is a synchronous buck regulator. The device
provides 3A of continuous load current over a wide input voltage
of 4V~28V. Current mode control provides fast transient response
and cycle by cycle current limit. Integrates soft start, and
shutdown mode.
The UTC
SR2803
can provide low-ripple power, high
efficiency, and perfect transient characteristics. The duty ratio
varies linearly from 0% to 92% in the PWM control. The error
amplifier circuit and soft-start circuit included in this device can
prevent overshoot at startup. An enable function, an over current
protect (OCP) function and short circuit protect (SCP) are also
build inside, and when OCP happens, the operation frequency
will be reduced.
LINEAR INTEGRATED CIRCUIT
FEATURES
* Input voltage varies from 4V ~ 28V
* Output voltage varies from 0.8V to V
CC
* Duty ratio varies from 0% to 92% PWM control
* With 330kHz typical oscillation frequency
*
Thermal shutdown and SCP function and soft-start, current limit,
enable function
* Low ESR output capacitor(Multi-layer chip capacitor) application
* Halogen Free
ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
SR2803L-S08-R
SR2803G-S08-R
Package
SOP-8
Packing
Tape Reel
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Copyright © 2012 Unisonic Technologies Co., Ltd
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QW-R103-056.A
SR2803
PIN CONFIGURATION
LINEAR INTEGRATED CIRCUIT
PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6
7
8
PIN NAME
FB
EN
COMP
V
CC
SW
SW
V
SS
V
SS
DESCRIPTION
Feedback pin
Power-off pin
H: normal operation (Step-down)
L: Step-down operation stopped (All circuits deactivated)
Compensation pin
IC power supply pin
Switch pin. Connect external inductor here.
Switch pin. Connect external inductor here.
GND pin
GND pin
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QW-R103-056.A
SR2803
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
V
CC
Current
Source
Bias
SENSE
Driver
PWM
LATCH
Dead Time
Control
EN
Start Up
REF_2.5V
REF_0.8V
OSC
FB
EA
SLOPE
PWM
SW
Driver
SS
COMP
GND
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QW-R103-056.A
SR2803
PARAMETER
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATING
(T
A
=25°C, unless otherwise specified )
SYMBOL
RATINGS
UNIT
V
CC
Pin Voltage
V
CC
V
SS
-0.3 ~V
SS
+28
V
Feedback Pin Voltage
V
FB
V
SS
-0.3 ~ V
CC
V
ON/OFF Pin Voltage
V
EN
V
SS
- 0.3 ~ V
CC
+ 0.3
V
Switch Pin Voltage
V
SW
V
SS
- 0.3 ~ V
CC
+ 0.3
V
Operating Supply Voltage
V
OP
+4 ~ 28
V
Power Dissipation
P
D
Internally limited
Storage Temperature
T
STG
-40 ~ +150
°C
Operating Temperature
T
OPR
-20 ~ +125
°C
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
THERMAL DATA
PARAMETER
SYMBOL
RATINGS
UNIT
Junction to Ambient
θ
JA
70
°С/W
Junction to Case
θ
JC
25
°С/W
Note:
θ
JA
is measured with the PCB copper area(need connect to SW pins) of approximately 1 in2(Multi-layer)
ELECTRICAL CHARACTERISTICS
(V
IN
= 12V, Ta= 25°C, unless otherwise specified.)
PARAMETER
Feedback Voltage
Feedback Bias Current
Switch Current
Standby Current
Quiescent Current
Oscillation Frequency
Frequency of Current Limit or Short
Circuit Protect
Line Regulation
Load Regulation
EN Pin Input Current
Soft-Start Time
Internal MOSFET R
DS(ON)
EN Pin Logic input threshold voltage
Thermal shutdown Temp
SYMBOL
V
FB
I
FB(BIAS)
I
SW
I
STN-BY
I
Q
f
OSC
f
OSC1
Δ
V
OUT
V
OUT
Δ
V
OUT
V
OUT
TEST CONDITIONS
I
OUT
=0.2A
I
OUT
=0.1A
Pear current, No outside circuit
V
FB
=0V Force driver on
V
EN
=0V No outside circuit V
FB
=0V
Force driver on
V
FB
=1.2V Force driver off
Measure waveform at SW Pin
Measure waveform at SW Pin
V
CC
=5V-28V, I
OUT
=0.2A
I
OUT
=0.2A-3A
V
EN
=2.5V(ON)
V
EN
=0.3V(OFF)
MIN TYP MAX UNIT
0.784 0.80 0.816
V
0.1
0.5
μA
3.5
2
260
20
3
330
40
0.4
0.3
5
0
3.5
70
50
10
5
400
A
μA
mA
KHz
KHz
%
%
μA
μA
ms
mΩ
mΩ
V
V
°C
I
SH
I
SL
T
SS
R
DS(ON)
V
SH
V
SL
TSD
0.3
High-side Switch, I
SW
=1A
low-side Switch, I
SW
=1A
High(regulator ON)
Low(regulator OFF)
8
1.6
0.8
150
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QW-R103-056.A
SR2803
TYPICAL APPLICATION CIRCUIT
MLCC
LINEAR INTEGRATED CIRCUIT
FB
V
SS
EN
V
SS
100k
COMP
Rc
10k
Co2
10n
+ V5
- 12
V
CC
Cin
22µF
SW
L4
10µH
Cout
22µF
Rbf2
6.8K
Rbf1
1.3K
5V/3A
SW
Co1
51P
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QW-R103-056.A
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