Low-Output-Voltage, 800mA, PWM Step-Down

DC-DC Converters

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3

ELECTRICAL CHARACTERISTICS (continued)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

N-Channel Synchronous Rectifier Turn-Off

Threshold

20

mA

LX Leakage Current

-20

0.1

+20

µA

Maximum Duty Cycle

100

%

PWM = GND

0

Minimum Duty Cycle

PWM = BATT

15

%

Internal Oscillator Frequency

0.85

1

1.15

MHz

Thermal Shutdown Threshold

15°C hysteresis

160

Degrees

POK COMPARATOR

BATT Operating Voltage Range

1

5.5

V

Output Low Voltage

0.01

0.1

V

Output High Leakage Current

1

µA

MAX1927R

0.650

0.675

0.700

MAX1928-15

1.305

1.350

1.395

MAX1928-18

1.566

1.620

1.674

POK Threshold

MAX1928-25

2.175

2.250

2.325

V

Output Valid to POK Release Delay

POK transitions to high impedance 20ms

15

20

25

ms

LOGIC INPUTS (SHDN, PWM)

Logic Input High

1.6

V

Logic Input Low

0.6

V

Logic Input Current

0.1

1

µA

ELECTRICAL CHARACTERISTICS

PARAMETER

CONDITIONS

MIN

MAX

UNITS

BATT Input Voltage

2.6

5.5

V

Undervoltage Lockout Threshold

2.15

2.55

V

Quiescent Current

No load, pulse skipping, PWM = GND

240

µA

Quiescent Current in Dropout

340

µA

Shutdown Supply Current

SHDN = GND

10

µA

REFERENCE AND ERROR AMP

MAX1927R

0.732

0.768

MAX1928-15

1.47

1.53

MAX1928-18

1.764

1.836

FB Voltage Accuracy

MAX1928-25

2.45

2.55

V

FB Input Current

MAX1928

5

15

µA