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UNISONIC TECHNOLOGIES CO., LTD SR2803
330KHZ, 3A SYNCHRONOUS BUCK CONTROLLER
DESCRIPTION
LINEAR INTEGRATED CIRCUIT
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.
FEATURES
* Input voltage varies from 4V ~ 28V * Output voltage varies from 0.8V to VCC * 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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QW-R103-056.A
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SR2803
PIN CONFIGURATION
LINEAR INTEGRATED CIRCUIT
PIN DESCRIPTION
PIN NO. 1 2 3 4 5 6 7 8 PIN NAME FB EN COMP VCC SW SW VSS VSS 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
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
2 of 6
QW-R103-056.A
Free
Datasheet
http://www.Datasheet4U.com
SR2803
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
VCC 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
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R103-056.A
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SR2803
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified )
PARAMETER SYMBOL RATINGS UNIT VCC Pin Voltage VCC VSS -0.3 ~VSS +28 V Feedback Pin Voltage VFB VSS -0.3 ~ VCC V ON/OFF Pin Voltage VEN VSS - 0.3 ~ VCC+ 0.3 V Switch Pin Voltage VSW VSS - 0.3 ~ VCC+ 0.3 V Operating Supply Voltage VOP +4 ~ 28 V Power Dissipation PD Internally limited Storage Temperature TSTG -40 ~ +150 °C Operating Temperature TOPR -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 θJA 70 °С/W Junction to Case θJC 25 °С/W Note: θJA is measured with the PCB copper area(need connect to SW pins) of approximately 1 in2(Multi-layer)
ELECTRICAL CHARACTERISTICS (VIN = 12V, Ta= 25°C, unless otherwise specified.)
SYMBOL VFB IFB(BIAS) ISW ISTN-BY IQ fOSC fOSC1
ΔVOUT VOUT ΔVOUT VOUT
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 RDS(ON) EN Pin Logic input threshold voltage Thermal shutdown Temp
TEST CONDITIONS IOUT=0.2A IOUT=0.1A Pear current, No outside circuit VFB=0V Force driver on VEN=0V No outside circuit VFB=0V Force driver on VFB=1.2V Force driver off Measure waveform at SW Pin Measure waveform at SW Pin VCC=5V-28V, IOUT=0.2A IOUT=0.2A-3A VEN=2.5V(ON) VEN=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
ISH ISL TSS RDS(ON) VSH VSL TSD
0.3 High-side Switch, ISW=1A low-side Switch, ISW=1A High(regulator ON) Low(regulator OFF)
8
1.6 0.8 150
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
4 of 6
QW-R103-056.A
Free Datasheet http://www.Datasheet4U.com
SR2803
TYPICAL APPLICATION CIRCUIT
MLCC
LINEAR INTEGRATED CIRCUIT
FB
VSS
EN
VSS
100k COMP Rc 10k Co2 10n + V5 - 12 VCC Cin 22µF SW L4 10µH Cout 22µF Rbf2 6.8K Rbf1 1.3K 5V/3A SW
Co1 51P
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R103-056.A
Free Datasheet http://www.Datasheet4U.com
SR2803
TYPICAL CHARACTERISTICS
Short Protect SW Wave VIN=19V, VOUT=5V, ILOAD=3A
LINEAR INTEGRATED CIRCUIT
Short Protect SW Wave VIN=19V, VOUT=0V
5V 0 0 12.5 Time (2.5μs/div) 25 5V 0 0 125 Time (25μs/div) 250
Efficiency (%)
UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, .