High-Voltage, Step-Down Controller with

Synchronous Rectifier for CPU Power

2

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

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.

V+ to GND ................................................................-0.3V to 36V

GND to PGND........................................................................±2V

VL to GND...................................................................-0.3V to 7V

BST to GND ..............................................................-0.3V to 46V

DH to LX .....................................................-0.3V to (BST + 0.3V)

LX to BST ....................................................................-7V to 0.3V

SHDN to GND ...........................................................-0.3V to 36V

SYNC, SS, REF, FB, SKIP, DL to GND ...........-0.3V to (VL + 0.3V)

CSH, CSL to GND.......................................................-0.3V to 7V

VL Short Circuit to GND..............................................Momentary

REF Short Circuit to GND ...........................................Continuous

VL Output Current ...............................................................50mA

SO (derate 8.70mW/°C above +70°C) ........................696mW

Operating Temperature Range

MAX797HESE .................................................-40°C to +85°C

Storage Temperature Range .............................-65°C to +160°C

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

Rising edge, hysteresis = 25mV

V+

Rising edge, hysteresis = 15mV

CSH - CSL, negative

CSH - CSL, positive

FB = VL, 6V < power input < 40V (Note 4)

25mV < (CSH - CSL) < 80mV

0mV < (CSH - CSL) < 80mV, FB = VL,

6V < power input < 40V, includes line and load

regulation (Note 4)

External resistor divider

CSH - CSL = 0V

0mV < (CSH - CSL) < 80mV

CONDITIONS

V

4.2

4.7

VL/CSL Switchover Voltage

V

3.8

4.1

VL Fault Lockout Voltage

V

4.7

5.3

VL Output Voltage

mA

2.0

SS Fault Sink Current

µA

2.5

4.0

6.5

SS Source Current

40

V

4.5

30

Input Supply Range

-50

-100

-160

mV

80

100

120

Current-Limit Voltage

1.5

V

4.85

5.10

5.25

5V Output Voltage (CSL)

V

REF

6

Nominal Adjustable Output

Voltage Range

V

2.43

2.505

2.57

Feedback Voltage

%

2.5

Load Regulation

UNITS

MIN

TYP

MAX

PARAMETER

High-side MOSFET drain

0mV < (CSH - CSL) < 80mV, FB = 0V,

4.5V < power input < 40V, includes line and load

regulation (Note 4)

V

3.20

3.35

3.46

3.3V Output Voltage (CSL)

FB = 0V, 4.5V < power input < 40V (Note 4)

%/V

0.04

0.06

Line Regulation

+3.3V AND +5V STEP-DOWN CONTROLLERS

FLYBACK/PWM CONTROLLER

INTERNAL REGULATOR AND REFERENCE

0.04

0.06