MAX1844 datasheet(2/24 Pages) MAXIM

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High-Speed Step-Down Controller with

Accurate Current Limit for Notebook Computers

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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 +28V

VCC, VDD to GND .....................................................-0.3V to +6V

OUT, PGOOD, SHDN to GND ..................................-0.3V to +6V

FB, ILIM, LATCH, OVP, REF, SKIP,

TON, UVP to GND ..................................-0.3V to (VCC + 0.3V)

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

CS to GND.................................................................-6V to +30V

DL to GND ..................................................-0.3V to (VDD + 0.3V)

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

LX to BST..................................................................-6V to +0.3V

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

Continuous Power Dissipation (TA = +70°C)

20-Pin QSOP (derate 9.1mW/

°C above +70°C)...........727mW

20-Pin 5mm ✕ 5mm QFN (derate 20.0mW/°C

above +70°C).................................................................1.60W

Operating Temperature Range ...........................-40

°C to +85°C

Junction Temperature ......................................................+150

°C

Storage Temperature Range .............................-65

°C to +150°C

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

°C

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V+ = 15V, VCC = VDD = 5V, SKIP = GND, TA = 0

°C to +85°C, unless otherwise noted. Typical values are at

TA = +25

°C.)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Battery voltage, V+

Input Voltage Range

VCC , VDD

4.5

5.5

FB = OUT

0.99

1.01

FB = GND

2.475

2.5

2.525

Error Comparator Threshold

(DC Output Voltage Accuracy)

(Note 1)

V+ = 4.5V to 28V,

SKIP = VCC

FB = VCC

1.782

1.8

1.818

Load Regulation Error

ILOAD = 0 to 3A, SKIP = VCC

Line Regulation Error

VCC = 4.5V to 5.5V, V+ = 4.5V to 28V

FB Input Bias Current

-0.1

+0.1

µA

Output Adjustment Range

5.5

FB = GND

190

350

OUT Input Resistance

FB = VCC or adjustable feedback mode

145

270

Ω

Soft-Start Ramp Time

Rising edge of SHDN to full current limit

1.7

TON = GND (600kHz)

140

160

180

TON = REF (450kHz)

175

200

225

TON = unconnected (300kHz)

260

290

320

On-Time

V+ = 24V,

VOUT = 2V

(Note 2)

TON = VCC (200kHz)

380

425

470

Minimum Off-Time

(Note 2)

400

500

Quiescent Supply Current (VCC)

FB forced above the regulation point

550

800

µA

Quiescent Supply Current (VDD)

FB forced above the regulation point

µA

Quiescent Supply Current (V+)

µA

Shutdown Supply Current (VCC)

SHDN = GND

µA

Shutdown Supply Current (VDD)

SHDN = GND

µA

Shutdown Supply Current (V+)

SHDN = GND, V+ = 28V, VCC = VDD = 0 or 5V

µA

Reference Voltage

VCC = 4.5V to 5.5V, no external REF load

1.98

2.00

2.02

Reference Load Regulation

IREF = 0 to 50µA

0.01

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