User guide

MAX1846/MAX1847
High-Efficiency, Current-Mode,
Inverting PWM Controller
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ELECTRICAL CHARACTERISTICS (continued)
(V
SHDN
= V
IN
= +12V, SYNC = GND, PGND = GND, R
FREQ
= 147kΩ ±1%, C
VL
= 0.47µF, C
REF
= 0.1µF, T
A
= 0°C to +85°C, unless
otherwise noted.)
OSCILLATOR
R
FREQ
= 500kΩ ±1% 90 100 110
R
FREQ
= 147kΩ ±1% 255 300 345 Oscillator Frequency
R
FREQ
= 76.8kΩ ±1% 500
kHz
R
FREQ
= 500kΩ ±1% 93 96 97
R
FREQ
= 147kΩ ±1% 85 88 90
Maximum Duty Cycle
R
FREQ
= 76.8kz ±1% 80
%
SYNC Input Signal Duty-Cycle
Range
7 93 %
Minimum SYNC Input Logic Low
Pulse Width
50 200 ns
SYNC Input Rise/Fall Time (Note 2) 200 ns
SYNC Input Frequency Range 100 550 kHz
DIGITAL INPUTS
POL, SYNC, SHDN Input High
Voltage
2.0 V
POL, SYNC, SHDN Input Low
Voltage
0.45 V
POL, SYNC Input Current POL, SYNC = GND or VL 20 40 µA
V
SHDN
= +5V or GND -12 -4 0
SHDN Input Current
V
SHDN
= +16.5V 1.5 6
µA
SOFT-START
Soft-Start Clock Cycles 1024
Cycles
Soft-Start Levels 64
EXT OUTPUT
EXT Sink/Source Current V
IN
= +5V, V
EXT
forced to +2.5V 1 A
EXT high or low, tested with 100mA load, V
IN
= +5V 2 5
EXT On-Resistance
EXT high or low, tested with 100mA load, V
IN
= +3V 5 10
Ω
Note 1: Production test correlates to operating conditions.
Note 2: Guaranteed by design and characterization.