
MAX1845
Dual, High-Efficiency, Step-Down
Controller with Accurate Current Limit
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
DD
= V
CC
= 5V, SKIP = GND, V+ = 15V, T
A
= -40°C to +85°C, unless otherwise noted.) (Note 1)
PWM CONTROLLERS
V+ Battery voltage, V+ 2 28
Input Voltage Range
V
CC
/V
DD
V
CC
, V
DD
4.5 5.5
V
FB1 to GND
1.773 1.827
1.477 1.523
D C O utp ut V ol tag e, O U T1 ( N ote 2)
V
OUT1
V+ = 2V to 28V, SKIP = V
CC
,
I
LOAD
= 0 to 10A
FB1 to OUT1 0.985 1.015
2.463 2.537
D C O utp ut V ol tag e, O U T2 ( N ote 2)
V
OUT2
V+ = 2V to 28V, SKIP = V
CC
,
I
LOAD
= 0 to 10A
FB2 to OUT2 0.985 1.015
V
Output Voltage Adjust Range OUT1, OUT2 1 5.5 V
Dual-Mode Threshold (Low) OVP, FB_
0.05 0.15
V
OVP, ILIM_
V
CC
-
1.5
V
CC
-
0.4
Dual-Mode Threshold (High)
FB_ 1.9 2.1
V
R
OUT1
V
OUT1
= 1.5V 75
OUT_ Input Resistance
R
OUT2
100
kΩ
FB_ Input Bias Current I
FB
-0.1
120
153
217
272
On-Time, Side 1 (Note 3) t
ON1
V+ = 24V, V
OUT1
= 2V
308
160
205
295
371
On-Time, Side 2 (Note 3) t
ON2
V+ = 24V, V
OUT2
= 2V
422
125
125
125
145
On-Time Tracking (Note 3)
On-time 2, with
respect to on-time 1
TON = V
CC
125
145
%
Minimum Off-Time (Note 3) t
OFF
500 ns
Quiescent Supply Current (V
CC
)I
CC
FB forced above the regulation point
1500
µA
Quiescent Supply Current (V
DD
)I
DD
FB forced above the regulation point 5 µA
Quiescent Supply Current (V+) I+ Measured at V+ 70 µA
Reference Voltage V
REF
V
CC
= 4.5V to 5.5V, no external REF load
1.98 2.02
V
Reference Load Regulation I
REF
= 0 to 50uA
0.01
V
Overvoltage Trip Threshold
(Fixed-Threshold Mode)
OVP = GND, with respect to FB_ regulation
point, no load
112
117 %
Output Undervoltage Threshold
UVP = V
CC
, with respect to FB_ regulation
point, no load
65 75 %
Current-Limit Threshold (Fixed) GND - V
CS
, ILIM_ = V
CC
35 65 mV
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