ltc3440 Linear Technology Corporation, ltc3440 Datasheet - Page 17

• Manufacturer Part Number: ltc3440
• Description: Micropower Synchronous Buck-boost Dc/dc Converter
• Manufacturer: Linear Technology Corporation

TYPICAL APPLICATIO S
V
Li-Ion
IN
= 2.5V TO 4.2V
+
*1 = Burst Mode OPERATION
** LOCATE COMPONENTS AS
0 = FIXED FREQUENCY
CLOSE TO IC AS POSSIBLE
WCDMA Power Amp Power Supply with Dynamic Voltage Control
USB/PCMCIA POWER
C1
10μF
2.5V TO 5.5V
500mA MAX
*
R
30.1k
3
7
8
2
1
T
SW1
V
SHDN/SS
MODE/SYNC
R
V
IN
IN
T
f
OSC
LTC3440
3.3μH
GSM Modem Powered from USB or PCMCIA with 500mA Input Current Limit
L1
= 2MHz
C1, C2: TAIYO YUDEN JMK212BJ106MM
D1: ON SEMICONDUCTOR MBRM120T3
L1: SUMIDA CDRH4D28-3R3
0.1Ω
R
S
R4
1k
V
SW2
GND
OUT
V
FB
C
U
4
6
9
10
5
+
1/2 LT1490A
–
C1
10μF
D1**
R3 15k
*
C5 10pF
R
60.4k
3
7
8
2
1
T
C4 150pF
SW1
V
SHDN/SS
MODE/SYNC
R
IN
T
LTC3440
340k
DAC
10μH
2N3906
R1
L1
V
SW2
GND
OUT
R2
200k
FB
V
C
I
V
CURRENTLIMIT
R5
10k
4
6
9
10
5
OUT
200k
C3
33pF
R6
= 3.3V – 1.7V • (V
10nF
C5
=
1.22 • R4
3440 TA07a
R5 • R
C2**
10μF
V
0.4V TO 5V
OUT
S
130k
R6
DAC
– 1.22V)
1N914
R5
24k
C1: TAIYO YUDEN JMK212BJ106MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: SUMIDA CDRH-4D28-100
*1 = Burst Mode OPERATION
0 = FIXED FREQUENCY
1/2 LT1490A
100
84
82
98
96
94
92
90
88
86
80
+
–
2.5
V
OUT
Power Amp Power Supply
Efficiency of the WCDMA
= 3.4V
3
I
OUT
R1
392k
R2
200k
I
INPUT VOLTAGE (V)
OUT
= 250mA
3.5
= 600mA
I
3440 TA08
OUT
C6 TO C9
470μF
×4
V
3.6V
2A
(PULSED)
OUT
LTC3440
= 100mA
4
4.5
17
3440 TA07b
3440fb
5