User guide

MAX1846/MAX1847
High-Efficiency, Current-Mode,
Inverting PWM Controller
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COMP
C
COMP
R
COMP
R
FREQ
GND
FREQ
VL
V
IN
V
OUT
C
OUT
C
IN
1
9
8
7
5
4
2
3
P
L1
R
CS
C
FB
D1
10
22k
0.47µF
0.1µF
6
EXT
PGND
REF
IN
CS
FB
MAX1846
R2
R1
APPLICATION B
ONLY
NOTE: APPLICATIONS A & B USE POS CAPACITORS. APPLICATIONS C & D USE ALUMINUM ELECTROLYTIC CAPACITORS.
Figure 2. MAX1846 Main Application Circuit
CIRCUIT ID ABCD
Input (V) 12 3 to 5.5 12 12
Output (V) -5 -12 -48 -72
Output (A) 2 0.4 0.1 0.1
C
COMP
(µF) 0.047 0.22 0.068 0.1
C
IN
(µF) 3 x 10 3 x 22 10 10
C
OUT
(µF) 2 x 100 2 x 47 47 33
C
FB
(pF) 390 1200 1800 1800
R1 (kΩ) (1%) 40.2 95.3 383 576
R2 (kΩ) (1%)10101010
R
COMP
(kΩ) 8.2 10 150 1800
R
CS
(Ω) 0.02 0.02 0.05 0.05
R
FREQ
(kΩ) 150 150 150 150
D1 CMSH5-40 CMSH5-40 CMR1U-02 CMR1U-02
L1 (µH) 10 10 47 82
P1
FDS6685 FDS6375 IRFR5410 IRFR5410
Table 1. Component List for Main Application Circuits