LTC3440_15 Datasheet, PDF (17/20 Pages) Linear Technology – Micropower Synchronous Buck-Boost DC/DC Converter

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