Datasheet

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