User guide

MAX1846/MAX1847
High-Efficiency, Current-Mode,
Inverting PWM Controller
6 _______________________________________________________________________________________
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX1846/7 toc10
0
2
6
4
12
14
10
8
16
SHUTDOWN SUPPLY CURRENT (µA)
-40 0 20-20
40
60 80 100
TEMPERATURE (°C)
V
IN
= 10V
V
IN
= 16.5V
V
IN
= 3V
0
4
2
8
6
12
10
14
-40 0 20-20 40 60 80 100
OPERATING CURRENT
vs. TEMPERATURE
MAX1846/7 toc11
TEMPERATURE (°C)
OPERATING CURRENT (mA)
A
B
C
A: V
IN
= 3V, V
OUT
= -12V
B: V
IN
= 5V, V
OUT
= -5V
C: V
IN
= 16.5V, V
OUT
= -5V
APPLICATION CIRCUIT A
0
100
300
200
400
500
0 200100 300 400 500 600
SWITCHING FREQUENCY
vs. R
FREQ
MAX1846/7 toc12
R
FREQ
(kΩ)
f
OSC
(kHz)
SWITCHING FREQUENCY
vs. TEMPERATURE
MAX1846/7 toc13
294
295
297
296
300
301
299
298
302
FREQUENCY (kHz)
-40 0 20-20
40
60 80 100
TEMPERATURE (°C)
R
FREQ
= 147kΩ ±1%
0
40
20
60
120
140
100
80
160
0 2000 4000 6000 8000 10,000
EXT RISE/FALL TIME
vs. CAPACITANCE
MAX1846/7 toc14
CAPACITANCE (pF)
TIME (ns)
RISE TIME
FALL TIME
V
IN
= 12V
I
L
0
5V/div
1A/div
5V/div
V
OUT
EXITING SHUTDOWN
MAX1846/7 toc15
APPLICATION CIRCUIT B
1ms/div
SHDN
Typical Operating Characteristics (continued)
(Circuit references are from Table 1 in the Main Application Circuits section, C
VL
= 0.47µF, C
RE
F
= 0.1µF, T
A
= +25°C, unless otherwise
noted.)
1.240
1.245
1.255
1.250
1.260
0 100 200 300 400 500
REFERENCE LOAD REGULATION
MAX1846/7 toc07
I
REF
(µA)
V
REF
(V)
4.100
4.180
4.140
4.260
4.220
4.300
4.340
-40 20 40-20 0 60 80 100
VL VOLTAGE
vs. TEMPERATURE
MAX1846/7 toc08
TEMPERATURE (°C)
VL (V)
I
VL
= 0
4.22
4.23
4.24
4.25
4.26
4.27
0 0.8 1.00.4 0.60.2 1.2 1.4 1.6 1.8 2.0
VL LOAD REGULATION
MAX1846/7 toc09
I
VL
(mA)
VL (V)