Datasheet
LTC3421
16
3421f
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003
LT/TP 1103 1K PRINTED IN USA
TYPICAL APPLICATIO
U
Single Cell to 3.3V at 500mA with Secondary Cell Backup During Shutdown. LOWBAT and V
REF
Output are Enabled
SHDN
ENB
V
REF
LBI
LBO
SYNC
I
LIM
V
OUTS
V
OUT
V
OUT
V
OUT
FB
V
C
BURST
V
IN
221141516
18
17
19
20
1
24
9
1312111056
8
7
22
23
3
4
SW SW
L1
4.7µH
SW
SS R
T
GND
LTC3421
C2
0.1µF
C3
0.1µF
C4
470pF
C5*
22µF
C1*
4.7µF
V
IN
1V TO 1.5V
1 CELL
PRIMARY CELL
LOW BAT
OUTPUT
R2
28k
R3
40k
R4
100k
R5
340k
3V
SECONDARY CELL
V
OUT
3.3V
500mA
R6
200k
3421 TA05
R1
60k
604k
301k
0.1µF
*LOCATE COMPONENTS CLOSE TO PINS
C1: TAIYO YUDEN JMK212BJ106MM
PGND PGND PGND
D1
+
+
C5: TAIYO YUDEN JMK325BJ226MM
L1: TOKO A916CY-4R7M
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LT1371/LT1371HV 3A (I
SW
), 500kHz, High Efficiency Step-Up DC/DC V
IN
: 2.7V to 30V, V
OUT(MAX)
: 35V/42V, I
Q
: 4mA, I
SD
: <12µA,
Converters DD, TO220-7, S20
LTC3400/LTC3400B 600mA (I
SW
), 1.2MHz, Synchronous Step-Up DC/DC 92% Efficiency, V
IN
: 0.85V to 5V, V
OUT(MAX)
: 5V, I
Q
: 19µA/300µA,
Converters I
SD
: <1µA, ThinSOT
LTC3401 1A (I
SW
), 3MHz, Synchronous Step-Up DC/DC Converter 97% Efficiency, V
IN
: 0.5V to 5V, V
OUT(MAX)
: 5.5V, I
Q
: 38µA,
I
SD
: <1µA, MS10
LTC3402 2A (I
SW
), 3MHz, Synchronous Step-Up DC/DC Converter 97% Efficiency, V
IN
: 0.5V to 5V, V
OUT(MAX)
: 5.5V, I
Q
: 38µA,
I
SD
: <1µA, MS10
LTC3425 5A (I
SW
), 8MHz, 4-Phase Synchronous Step-Up 95% Efficiency, V
IN
: 0.5V to 4.5V, V
OUT(MAX)
: 5.25V, I
Q
: 12µA,
DC/DC Converter 8MHz, Low Ripple in QFN
OUTPUT CURRENT (mA)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.1 10 100 1000
3421 G01
0
1
Burst Mode OPERATION
V
IN
= 1.5V
V
OUT
= 3.3V
f
OSC
= 1MHz
V
IN
= 1V
V
IN
= 1.2V
Single Cell to 3.3V Efficiency