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| USR1101_15 Datasheet, PDF (5/5 Pages) Unisonic Technologies – 5V/12V SYNCHRONOUS BUCK PWM DC-DC CONTROLLER | |||
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USR1101
Preliminary
LINEAR INTEGRATED CIRCUIT
ï® APPLICATION INFORMATION
OCP
Sense the low-side MOSFETâs RDS(ON) to set over-current trip point.
Connecting a resistor (ROCSET) from this pin to the source of the upper MOSFET and the drain of the lower
MOSFET sets the over-current trip point. ROCSET, an internal 40μA current source, and the lower MOSFET on
resistance, RDS(ON), set the converter over-current trip point (IOCSET) according to the following equation:
IOCSET
ï½
40ïA
RDS(ON) of
ï´ ROCSET ï 0.4V
the lower MOSFET
Shutdown
Pulling low the OPS pin by a small single transistor can shutdown the UTC USR1101 PWM controller as shown in
typical application circuit.
ï® TYPICAL APPLICATION CIRCUIT
+5V~+12V
D1
1N4148
R1
10
C1
1µF
UTC USR1101
1 BOOT
UGATE 2
5 VCC
6 FB
3 GND
NC 8
OPS 7
LGATE 4
C2
0.1µF
ROCSET
Disable
R2
R3
32
68
VIN
C3
1µF
M1
L1
3µH
C4
470µF
VOUT
COUT
M2
1000µFÃ3
R4
C5
200-1k 0.1-0.33µF
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
5 of 5
QW-R103-062.b
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