Step-Down Controllers with Prebias Startup,

Lossless Sensing, Synchronization, and OVP

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3

ELECTRICAL CHARACTERISTICS (continued)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

38.5

50

56.5

85

100

115

127.5

150

172.5

170

200

230

Ω (MAX8544 only)

-42.5

-50

-57.5

Ω (MAX8544 only)

-160

-200

-240

-110

-130

-150

Current-Limit Threshold

-20

-30

-40

mV

Negative Current-Limit Threshold

-25

-50

-85

%

CS+, CS- Input Current

-40

+40

µA

CS+, CS- Input Common-Mode Range

0

13.2

V

OSCILLATOR

Ω

800

1000

1200

Switching Frequency

Ω

200

kHz

Minimum Off-Time

Measured at DH

150

220

270

ns

Minimum On-Time

Measured at DH

90

145

ns

FSYNC Synchronization Range

160

1200

kHz

FSYNC Input High Pulse Width

100

ns

FSYNC Input Low Pulse Width

100

ns

FSYNC Rise/Fall Time

100

ns

SYNCO Phase Shift from DH Rising

Ω, free-running mode,

at maximum duty cycle

165

180

195

Degrees

SYNCO Output Low Level

0.4

V

SYNCO Output High Level

V

MOSFET DRIVERS

1

2.5

DH On-Resistance, High State

1.2

Ω

1

2.5

DH On-Resistance, Low State

1.2

Ω

1

2.5

DL On-Resistance, High State

1.2

Ω

0.6

1.7

DL On-Resistance, Low State

0.8

Ω

Low-side off to high-side on

55

Break-Before-Make Dead Time

High-side off to low-side on

40

ns

LX, BST, IN Leakage Current

5

µA

THERMAL PROTECTION

Thermal Shutdown

Rising temperature

+160

°C

Thermal-Shutdown Hysteresis

15

°C