AN2738 datasheet(7/54 Pages) STMICROELECTRONICS

7 / 54 page

AN2738

UVLO function

Doc ID 14589 Rev 2

7/54

UVLO function

The L6390 supply voltage VCC is continuously monitored by an under-voltage lockout

(UVLO) circuitry which turns off the IC outputs when the supply voltage goes below the

VCC_thOFF threshold (see L6390 datasheet for values) and turns on the device when the

supply voltage goes above the VCC_thON voltage. A hysteresis of about 1.5 V is provided for

noise rejection purpose. The high voltage floating supply VBOOT is provided with a similar

under-voltage lockout circuitry also. When the L6390 is in UVLO condition, both gate driver

outputs are set to low level, setting the half-bridge power stage output to high impedance.

Figure 3 below shows the I-V characteristics of the output buffers at different VCC values.

Figure 3.

L6390 gate driver outputs in UVLO condition

VLVG/HVG

(V)

ILVG/HVG

(mA)

VCC = 0V

VCC = 1V

VCC = 2V

VCC = 3V

VCC = 4V

VCC = 5V

VCC = 6V

VCC = 7V

100

VCC = 9V

VCC = 15V

LVG/HVG

GND/OUT

VCC/BOOT

GATE DRIVER

OUTPUT BUFFER

(LS/HS)

n-channel

(sink)

p-channel

(source)

OFF

VCC

VLVG/HVG

ILVG/HVG

NOTE: when VCC <

VLVG/HVG

the body diode of the p-channel (source)

turns ON and clamps the

VLVG/HVG voltage

TEST CIRCUIT

AN2738 Datasheet(PDF) 7 Page - STMicroelectronics

AN2738 Datasheet(HTML) 7 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Datasheet Download

Link URL