Datasheet

LT1940/LT1940L
17
1940fa
5V/3.3V with Tantalum Output Capacitors
V
IN
7V TO 25V
BOOST1
SW1
FB1
V
C1
PG1
RUN/SS1
BOOST2
SW2
FB2
V
C2
PG2
RUN/SS2
LT1940
V
IN
GND
1940 TA03
100pF
C2
47µF
10V
C1
100µF
6.3V
C3
4.7µF
0.1µF 0.1µF
20k
220pF
10.0k
10.0k
16.5k
100k
30.1k
100k
L2
4.7µH
L1
3.3µH
5 GOOD
3V3
GOOD
OUT2
5V
1.2A
OUT1
3.3V
1.2A
D2
10.0k
D1
D3
1nF 1nF
D4
+
+
D1, D2: MICROSEMI UPS140 OR ON SEMI MBRM140
D3, D4: CENTRAL CMDSH-3
L1: SUMIDA CDRH4D28-3R3
L2: SUMIDA CDRH4D28-4R7
C1: AVX TPSC107M010R0150
C2: AVX TPSC476M010R0350
C3: TAIYO YUDEN TMK325BJ475ML
TYPICAL APPLICATIO S
U
V
IN
4.7V TO 14V
1940 TA01
330pF
C2
10µF
C1
22µF
C3
4.7µF
0.1µF 0.1µF
15k
220pF
20k
10.0k
10.0k
100k
16.5k
L2
3.3µH
L1
2.2µH
POWER
GOOD
OUT2
3.3V
1A
(1.4A FOR V
IN
> 5V)
OUT1
1.8V
1.4A
D2
22.6k
D1
D3
1nF
D1, D2: MICROSEMI UPS120
D3, D4: CENTRAL CMDSH-3
L1: SUMIDA CR43-2R2
L2: SUMIDA CR43-3R3
D4
C1: TAIYO YUDEN JMK316BJ226ML
C2: TAIYO YUDEN JMK316BJ106ML
C3: TAIYO YUDEN EMK316BJ475ML
BOOST1
SW1
FB1
V
C1
RUN/SS1
RUN/SS2
BOOST2
SW2
FB2
V
C2
PG1
PG2
LT1940
V
IN
GND
3.3V and 1.8V Outputs with Sequencing
Start-Up Waveforms
V
IN
2V/DIV
V
OUT1
2V/DIV
V
OUT2
2V/DIV
POWER GOOD
2V/DIV
50µs/DIV
1940 TA01b