MAX8553 datasheet(3/24 Pages) MAXIM

3 / 24 page

4.5V to 28V Input, Synchronous PWM Buck Controllers

for DDR Termination and Point-of-Load Applications

_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VV+ = VHSD = +12V, VEN/HSD = VREFIN = +2.5V, VEN = +5V, CVL = 4.7µF, CVTTR = 1µF, CREF = 0.22µF, VFSEL = 0V, ILIM = VL,

PGND = LX = GND, BST = VL, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise specified.)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

FB Regulation Voltage

MAX8554, VOUT = +2.5V, FSEL unconnected

0.598

0.607

0.616

Output Adjust Range

MAX8554 (Note 1)

0.6

3.5

VTT Line Regulation

VEN/HSD ±10%, VVTT = +1.25V, IOUT = 0A

±0.325

FB Line Regulation

MAX8554, VHSD ±10%, VOUT = +2.5V,

IOUT = 0A, FSEL unconnected

±0.325

VTT Load Regulation

0 < IOUT < +7A, VVTT = +1.25V

0.2

FB Load Regulation

MAX8554, 0 < IOUT < +7A, VOUT = +2.5V,

FSEL unconnected

0.2

REFERENCE

Reference Output Voltage

VV+ = VVL = +4.5 to +5.5V, IREF = 0

1.97

2.00

2.03

Reference Load Regulation

VV+ = VVL = +5V, IREF = 0 to 50µA

Reference UVLO

VV+ = VVL = +5V, reference rising, hysteresis = 27mV

1.5

1.6

1.7

VTTR

VTTR Output Voltage Range

1.8

IVTTR = -5mA to +5mA

49.5

50.5

IVTTR = -25mA to +25mA, VREFIN = +1.8V

VTTR Output Accuracy

IVTTR = -25mA to +25mA, VREFIN = +3.6V

49.5

50.5

% VREFIN

Thermal Shutdown

Rising temperature, typical hysteresis = 15

°C

+160

°C

SOFT-START

ILIM Ramp Period

Ramps the ILIM trip threshold from 20% to 100% in

20% increments

0.8

1.7

3.0

Output Predischarge Period

Rising edge of EN/HSD to the start of internal digital

soft-start

0.8

1.7

3.0

OSCILLATOR

FSEL = VL

200

FSEL = unconnected

300

FSEL = REF

400

Oscillator Frequency

FSEL = GND

550

kHz

FSEL = VL

2.18

2.5

2.83

FSEL unconnected

1.45

1.67

1.89

FSEL = REF

1.09

1.25

1.41

On-Time

MAX8553, VVTT = +1.25V

(Note 2)

FSEL = GND

0.82

0.91

1.00

µs

FSEL = VL

0.89

1.02

1.16

FSEL unconnected

0.61

0.71

0.80

FSEL = REF

0.43

0.49

0.56

On-Time

MAX8554, VOUT = +2.5V

(Note 2)

FSEL = GND

0.33

0.37

0.41

µs

Off-Time

(Note 2)

350

400

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