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LTC3772_15 Datasheet, PDF (15/20 Pages) Linear Technology – Micropower No RSENSE Constant Frequency Step-Down DC/DC Controller
TYPICAL APPLICATIO S
550kHz Micropower, 1A, 2-Cell Li-Ion to 3.3VOUT
Step-Down DC/DC Converter
100pF
15k
56.2k
ITH/RUN VIN
LTC3772
GND PGATE
IPRG
VFB
SW
22pF 174k
L1: SUMIDA CR43-4R7
Si2341DS
L1 4.7µH
UPS120
VIN
5V TO 8.4V
22µF
47µF
VOUT
3.3V
1A
3772 TA02a
Efficiency vs Load Current
100
VOUT = 3.3V
VIN = 5.5V
90
VIN = 7.2V
80
VIN = 8.4V
70
60
50
40
1
10
100
1000
LOAD CURRENT (mA)
10000
3772 TA02b
VOUT
2V/DIV
ITH/RUN
1V/DIV
IL
1A/DIV
Start-Up
VOUT
100mV/DIV
AC COUPLED
IL
500mA/DIV
ILOAD
500mA/DIV
Load Step
VIN = 5.5V
VOUT = 3.3V
RLOAD = 3Ω
500µs/DIV
3772 TA02c
VIN = 5.5V
20µs/DIV
VOUT = 3.3V
ILOAD = 40mA TO 500mA
LTC3772
3772 TA02d
3772f
15