
MAX1845
Dual, High-Efficiency, Step-Down
Controller with Accurate Current Limit
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DD
= V
CC
= 5V, SKIP = GND, V+ = 15V, T
A
= 0°C to +85°C, typical values are at +25°C, unless otherwise
noted.) (Note 1)
204
263
371
On-Time, Side 2 (Note 3) t
ON2
V+ = 24V,
V
OUT2
= 2V
TON = V
CC
432 483
534
145
145
145
On-Time Tracking (Note 3)
On-time 2 with
respect to on-
time 1
TON = V
CC
125 135
145
%
Minimum Off-Time (Note 3) t
OFF
400
500
ns
Quiescent Supply Current (V
CC
)I
CC
FB_ forced above the regulation point
1100 1500
µA
Quiescent Supply Current (V
DD
)I
DD
FB_ forced above the regulation point <1 5 µA
Quiescent Supply Current (V+) I+ Measured at V+ 25 70 µA
ON1 = ON2 = GND, OVP = V
CC
or GND <1 5
Shutdown Supply Current (V
CC
)
ON1 = ON2 = GND, V
OVP
= 1.8V 1 5
µA
Shutdown Supply Current (V
DD
) ON1 = ON2 = GND <1 5 µA
Shutdown Supply Current (V+)
ON1 = ON2 = GND, measured at V+,
V
CC
= GND or 5V
<1 5 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 50µA
0.01
V
REF Sink Current REF in regulation 10 µA
REF Fault Lockout Voltage Falling edge, hysteresis = 40mV 1.6 V
Overvoltage Trip Threshold
(Fixed-Threshold Mode)
OVP = GND, with respect to error-
comparator trip threshold
112 114
117
%
1V < V
OVP
< 1.8V, external feedback,
measured at FB_ with respect to V
OVP
-28 0 28 mV
Overvoltage Comparator Offset
(Adjustable-Threshold Mode)
1V < V
OVP
< 1.8V, internal feedback,
measured at OUT_ with respect to OUT_
regulation point
-3.5
+3.5
%
OVP Input Leakage Current 1V < V
OVP
< 1.8V
-100
100
nA
Overvoltage Fault Propagation
Delay
FB_ forced 2% above trip threshold 1.5 µs
Output Undervoltage Threshold
UVP = V
CC
, with respect to error-comparator
trip threshold
65 70 75 %
Output Undervoltage Protection
Blanking Time
From ON_ signal going high 10 30 ms
Current-Limit Threshold (Fixed) GND - V
CS
, ILIM_ = V
CC
40 50 60 mV
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