MAX1744/MAX1745
High-Voltage, Step-Down DC-DC
Controllers in µMAX
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(V
IN
= V
SHDN
= 5.5V to 36V, 3/5 = GND, I
LOAD
= 0, T
A
= -40°C to +125°C, unless otherwise noted.) (Note 1)
PARAMETER CONDITIONS MIN MAX UNITS
Input Voltage Range 4.5 36 V
Supply Current into IN V
SHDN
= V
IN
= 5.5V to 36V 140 μA
Shutdown Supply Current SHDN = GND 15 μA
3/5 = VL 4.85 5.15
Output Voltage (MAX1744)
3/5 = GND 3.20 3.40
V
OUT Input Current (MAX1744) 3/5 = VL, V
OUT
= 5V 44 μA
FB Threshold Voltage (MAX1745) Falling edge, hysteresis = 8mV 1.22 1.28 V
FB Input Current (MAX1745) -50 50 nA
VH Output Voltage with Respect to IN V
IN
= 5.5V to 36V, I
VH
= 100μA to 20mA -6.0V -4.3V V
VL Output Voltage V
IN
= 5.5V to 36V, I
VL
= 100μA to 2mA 4.5 5.5 V
VL Undervoltage Lockout 1.6 4.1 V
V
CS
= V
OUT
= 2.5V to 18V 85 115
CS Threshold Voltage
V
CS
= V
OUT
= V
GND
80 150
mV
V
CS
= V
OUT
= 2.5V to 18V 0 25
CS Input Current
V
CS
= V
OUT
= V
GND
-25 0
μA
SHDN, 3/5 Logic-High Threshold V
IN
= 4.5V to 36V 2.4 V
SHDN, 3/5 Logic-Low Threshold V
IN
= 4.5V to 36V 0.4 V
3/5 Input Current SHDN = GND ±1μA
3/5 = GND ±1
SHDN Input Current
V
SHDN
= 36V 12
μA
EXT Resistance 20 Ω
Minimum EXT Off-Time 1.5 2.5 μs
Minimum EXT On-Time 0.7 1.5 μs
Reference Voltage I
REF
= 0 1.22 1.28 V
REF Load Regulation 0 ≤ I
REF
≤ 100μA 10 mV
REF Line Regulation V
IN
= 4.5V to 36V, I
REF
= 0 80 μV/V
Note 1: Specifications to -40°C are guaranteed by design, not production tested.
