High-Voltage, Step-Down DC-DC

Controller in µMAX

2

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ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN = SHDN = 5.5V to 36V, 3/5 = GND, ILOAD = 0, TA = 0°C to +85°C, unless otherwise noted. Typical values at VIN = SHDN =

36V, TA = +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

IN, EXT, SHDN to GND...........................................-0.3V to +38V

VH to GND..............................................................-0.3V to +34V

VH, EXT to IN............................................................-7V to +0.3V

CS, OUT to GND ....................................................-0.3V to +20V

FB, 3/5, REF to GND .....................................-0.3V to (VL + 0.3V)

VL to GND...................................................................-0.3V to 6V

10-Pin µMAX (derate 5.6mW/°C above 70°C) .............444mW

Operating Temperature Range

MAX174_EUB ..................................................-40°C to +85°C

MAX174_AUB ................................................-40°C to +125°C

Junction Temperature ......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) ................................+300°C

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Input Voltage Range

4.5

36

V

Supply Current into IN

90

140

µA

Shutdown Supply Current

SHDN = GND

4

12

µA

3/5 = VL

4.85

5.00

5.15

Output Voltage (MAX1744)

3/5 = GND

3.20

3.30

3.40

V

OUT Input Current (MAX1744)

28

44

µA

FB Threshold Voltage (MAX1745)

Falling edge, hysteresis = 8mV

1.22

1.25

1.28

V

FB Input Current (MAX1745)

-50

50

nA

VH Output Voltage with Respect to IN

-6.0

-5.3

-4.3

V

VL Output Voltage

4.5

5.0

5.5

V

VL Undervoltage Lockout

2.0

3.0

4.1

V

85

100

115

CS Threshold Voltage

80

110

150

mV

0

15

25

CS Input Current

-25

0

µA

SHDN, 3/5 Logic-High Threshold

2.4

V

SHDN, 3/5 Logic-Low Threshold

0.4

V

3/5 Input Current

SHDN = GND

±1µA

3/5 = GND

±1

SHDN Input Current

SHDN = 36V

12

µA

EXT Resistance

820

Ω

Minimum EXT Off-Time

1.5

2.0

2.5

µs

Minimum EXT On-Time

0.7

1.0

1.5

µs

Output Line Regulation

5

mV/V

Output Load Regulation

15

mV/A

Reference Voltage

1.22

1.25

1.28

V

REF Load Regulation

0

4

10

mV

REF Line Regulation

30

60

µV/V