Datasheet

21
LTC3704
3704fb
APPLICATIO S I FOR ATIO
WUUU
P
D
= I
O(MAX)
• V
F
Assuming a maximum junction temperature of 125°C and
a forward voltage of approximately 0.33V at 3A (the
maximum output current at V
IN
= 15V), this diode will
dissipate 1W at full load. The diode selected was the
MBRD835L from On Semiconductor, packaged in a
D-Pak.
7. The DC coupling capacitor must be capable of handling
an RMS current of:
II
D
D
A
D PEAK O MAX
MAX
MAX
() ()
–•
–
==
1
3
Figure 15. 5V to 15V Input, –5V Output at 2A-3A(5A Peak)
Positive-to-Negative Converter with Soft-Start and Undervoltage Lockout.
Figure 16. Efficiency vs Output Current
Figure 17. Maximum Output Current vs Input Voltage
RUN
I
TH
NFB
FREQ
MODE/SYNC
SENSE
V
IN
INTV
CC
GATE
GND
LTC3704
R
T
80.6k
1%
R1
154k
1%
C
VCC
4.7μF
X5R
M1
C
IN
: TDK C5750X5R1C476M
C
DC
: TDK C5750X7R1C476M
C
OUT
: TDK C5750X5R0J107M
C
VCC
: TAIYO YUDEN LMK316BJ475ML
D1
•
L1*
L2*
C
OUT
100μF
X5R
(X2)
V
IN
5V to 15V
V
OUT
–5.0V
2A to 3A
(5A PEAK)
GND
D1: ON SEMICONDUCTOR MBRD835L
D2: CDMSH-3
L1, L2: BH ELECTRONICS BH510-1009
M1: SILICONICS/VISHAY Si4884
Q1: MMBT3904
R
C
3k
C
C1
4.7nF
C
IN
47μF
X5R
1
2
3
4
5
6
7
8
10
9
C
DC
47μF
X5R
3704 F15
R2
68.1k 1%
C1
1nF
R
FB1
1.21k
1%
R
FB2
3.65k
1%
Q1
D2
R
SS2
100Ω
C
SS
10nF
R
SS1
750Ω
•
OUTPUT CURRENT (A)
0.001
EFFICIENCY (%)
0.1
10
100
90
80
70
60
50
40
30
20
3704 F16
0.01 1
V
IN
= 5V
V
IN
= 15V
V
IN
= 10V
FET = Si4884
L = BH510-1009
V
O
= –5V
FREQ = 300kHz
INPUT VOLTAGE (V)
510
I
O(MAX)
(A)
6
5
4
3
2
1
0
3704 F17
15