LTC3520 Linear Technology, LTC3520 Datasheet - Page 21

• Manufacturer Part Number: LTC3520
• Description: Synchronous 1A Buck-Boost and 600mA Buck Converters
• Manufacturer: Linear Technology

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TYPICAL APPLICATIONS
600mA
V
1.8V
OUT
C1, C2, C3: TAIYO YUDEN CERAMIC JMK212BJ226MG-T
L1: TDK RLF7030T-4R7M3R4 4.7µH
L2: TDK RLF7030T-3R3M4R 3.3µH
Li-Ion
C2
22µF
BURST
V
2.2V TO 4.2V
IN
255k
200k
OFF
PWM
ON
C1
22µF
470pF
27pF
3.3µH
L2
0.022µF
54.9k
301k
BUCK-BOOST
BUCK V
3.3V at 500mA and 1.8V at 600mA Outputs
SD1, SD3
499k
5V/DIV
2V/DIV
5V/DIV
1V/DIV
SW2
FB2
SS2
R
PWM1
PWM2
SD3
SD1
SD2
PV
Sequenced Buck Converter Start-Up
T
V
A
Typical Waveforms During Power-Up
OUT
OUT
OUT
IN1
PGND1
PV
IN2
LTC3520
PV
SGND
IN3
SV
PGND2
IN
THE BUCK CONVERTER IS ENABLED WHEN THE
BUCK-BOOST OUTPUT VOLTAGE REACHES 3.0V.
1ms/DIV
SW1A
SW1B
V
A
OUT1
SS1
V
FB1
OUT
A
C1
IN
0.022µF
470pF
4.7µH
L1
15k
3520 TA02b
10k
56pF
1M
309k
C3
22µF
442k
158k
V
3.3V
500mA
1A FOR V
3520 TA02a
LTC3520
OUT
IN
≥ 3V
21
3520f