LTC3704_15 Datasheet, PDF (25/28 Pages) Linear Technology – Wide Input Range, No RSENSE Positive-to-Negative DC/DC Controller

APPLICATIO S I FOR ATIO
R_C
14.7k
C_C1
4.7nF
1
RUN
2
I_TH
10
SENSE
9
V_IN
LTC3704
3
8
NFB
INTV_CC
4
7
FREQ
GATE
5
6
MODE/SYNC GND
R_T
80.6k
1%
R_FB1
2.49k
1%
R_FB2
13.7k
1%
D1: DIODES INC B320B
L1, L2: BH ELECTRONICS BH 510-1009
M1: SILICONIX Si9426
C_VCC
4.7μF
X5R
•
L1*
•
L2*
V_IN
3V to 5V
V_OUT
–8.0V
1.2A to 2.5A
C_DC
M1 22μF
X5R
D1
C_IN
47μF
X5R
C_OUT
100μF
X5R
GND
3704 F24
Figure 24. 3V to 5V Input, –8V at 1.2A Output Converter
LTC3704
3
2
1
0
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
3704 F25
Figure 25. Maximum Output Current vs Input Voltage
100
95
90
V_IN = 5V
85
80
V_IN = 3V
75
70
65
60
55
50
0.001
0.01
0.1
1
10
OUTPUT CURRENT (A)
3704 F26
Figure 26. Output Efficiency at 3V and 5V Input
V_OUT (AC)
100mV/DIV
I_OUT (DC) ^1.2A
0.5A/DIV
0.6A
V_IN = 3V
250μs/DIV
3704 F27
Figure 27. Load Step Response at 3V Input
V_OUT (AC)
100mV/DIV
I_OUT (DC) ^1.2A
0.5A/DIV
0.6A
V_IN = 3V
250μs/DIV
3704 F27
Figure 28.Load Step Response at 5V Input
3704fb
25