Datasheet

LTC3429/LTC3429B
10
3429fa
TYPICAL APPLICATIO S
U
Applications Where V
OUT
> 4.3V
When the output voltage is programmed above 4.3V, it is
necessary to add a Schottky diode either from SW to V
OUT
,
or to add a snubber network in order to maintain an
acceptable peak voltage on the SW pin. The Schottky diode
between SW and V
OUT
will provide a peak efficiency
improvement but will negate the output disconnect fea-
ture. If output disconnect is required, an active snubber
network is suggested as shown below. Examples of Schot-
tky diodes are: MBR0520L, PMEG2010EA, 1N5817 or
equivalent.
Application Circuit for V
OUT
> 4.3V Where Inrush Current Limiting and Output Disconnect are Required
SW
L1
4.7µH
V
OUT
LTC3429
FB
V
IN
V
IN
2.7V TO 4.2V
SHDN
2
1
3
3429 TA04
R1
1.82M
R2
604k
C2
10µF
C3*
0.22µF
*LOCATE COMPONENTS CLOSE TO THE PIN
C1: TAIYO YUDEN X5R JMK212BJ475MM
C2: TAIYO YUDEN X5R JMK212BJ106MM
D1: MOTOROLA MBR0520L
L1: COILCRAFT D0160C-472
MP1: ZETEX ZXM61P02F
C1
4.7µF
Li-Ion
V
OUT
5V
250mA
MP1
5
D1*
4
6
GND
OFF
ON
+
Application Circuit for V
OUT
> 4.3V Where Inrush Current Limiting and Output Disconnect are Not Required
SW
L1
4.7µH
V
OUT
LTC3429
FB
V
IN
V
IN
SHDN
2
1
3
5
3429 TA05
R1
1.82M
R2
604k
C2
10µF
C1
4.7µF
2 AA
CELL
V
OUT
5V
150mA
D1*
4
6
+
GND
OFF
ON
*LOCATE COMPONENTS CLOSE TO THE PIN
C1: TAIYO YUDEN X5R JMK212BJ475MM
C2: TAIYO YUDEN X5R JMK212BJ106MM
D1: MOTOROLA MBR0520L
L1: COILCRAFT D0160C-472
Li-Ion to 5V Efficiency
OUTPUT CURRENT (mA)
60
EFFICIENCY (%)
80
100
50
70
90
0.1 10 100 1000
3429 TA04b
40
1
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 4.2V
POWER LOSS
0.01
POWER LOSS (W)
1
100
0.001
0.1
10
0.0001
EFFICIENCY
OUTPUT CURRENT (mA)
60
EFFICIENCY (%)
80
100
50
70
90
0.1 10 100 1000
3429 TA05b
40
1
V
IN
= 3V
0.01
POWER LOSS (W)
1
100
0.001
0.1
10
0.0001
POWER LOSS
V
IN
= 3V
V
IN
= 2.4V
EFFICIENCY
V
IN
= 2.4V
2-Cell to 5V Efficiency