L3751 datasheet(9/41 Pages) STMICROELECTRONICS

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Symbol

Parameter

Test conditions

Min.

Typ.

Max.

Unit

PGLTH

FB lower threshold for PGOOD high

to low

% of VREF, VFB falling

PGHYS_U

PGOOD upper threshold hysteresis

% of VREF

PGHYS_L

PGOOD lower threshold hysteresis

% of VREF

TPG-RISE (1) PGOOD rising filter

FB to PGOOD rising edge

10/FSW

µs

TPG-FALL (1) PGOOD falling filter

FB to PGOOD falling edge

10/FSW

µs

VPG-OL

PGOOD low state output voltage

VFB = 0.9 V, IPGOOD = 2 mA

150

IPG-OH

PGOOD high state leakage current

VFB = 0.8 V, VPGOOD = 13 V; TJ = 25 °C

100

Oscillator

FSW

Oscillator frequency

RRT = 100 kΩ

115

kHz

RRT = 25 kΩ

380

400

420

RRT = 11 kΩ

800

Synchronization input / output

FSYNC

SYNCIN external clock frequency

(> 100 kHz < 1 MHz)

% of nominal frequency set by RRT

-20

+50

VSYNC-IH

Minimum SYNCIN input logic high

VSYNC-IL

Maximum SYNCIN input logic low

0.8

RSYNCIN

SYNCIN input resistance

VSYNCIN = 3 V

kΩ

TSYNCI-PW SYNCIN input minimum pulse-width

Minimum high state or low state duration; TJ = 25

°C

VSYNCO-OH SYNCOUT high state output voltage

ISYNCOUT = –1 mA (sourcing)

VSYNCO-OL SYNCOUT low state output voltage

ISYNCOUT = 1 mA (sinking)

0.4

TSYNCOUT

Delay from HO rising to SYNCOUT

leading edge

VSYNCIN = 0 V, TS = 1/FSW, FSW set by RRT

TS/2-140

TSYNCIN

Delay from SYNCIN leading edge to

HO rising

50% to 50%, RT = 11 kΩ, VIN = 75 V

190

Bootstrap and BST UVLO

IQ-BST

BST to SW quiescent current, not

switching

VSS/TRK = 0 V, VSW = 48 V, VBST = 54 V

300

500

µA

VBST-UV

BST to SW undervoltage detection

VBST – VSW falling

3.4

VBST-HYS

BST to SW undervoltage hysteresis

VBST – VSW rising

0.42

PWM Control

TON(MIN)

Minimum controllable on-time

VBST – VSW = 7 V, HO 50% to 50%

TOFF(MIN)

Minimum off-time

VBST – VSW = 7 V, HO 50% to 50%

180

250

DCMAX

Maximum duty cycle

FSW = 100 kHz, 6 V ≤ VVIN ≤ 60 V

FSW = 400 kHz, 6 V ≤ VVIN ≤ 60 V

VRAMP(min)

Ramp valley voltage (COMP at 0%

duty cycle)

300

kFF

PWM feedforward gain (VIN / VRAMP) 6 V ≤ VVIN ≤ 75 V

V/V

PWM Control

IRS

ILIM source current, RSENSE

25 °C

100

110

µA

-40 °C to 125 °C

100

110

L3751

Electrical characteristics

DS13841 - Rev 1

page 9/41

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