LT3751EUFD datasheet(7/28 Pages) LINER

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LT3751

3751f

TYPICAL PERFORMANCE CHARACTERISTICS

OVLO1 (Pin 1): VTRANS Overvoltage Lockout Pin. Senses

when VTRANS rises above:

VOVLO1 = 1.225+ 50μA•ROVLO1

and trips the FAULT latch low, disabling switching. After

VTRANS drops below VOVLO1, toggling the CHARGE pin

reactivates switching.

UVLO2 (Pin 2): VCC Undervoltage Lockout Pin. Senses

when VCC drops below:

VUVLO2 = 1.225+ 50μA•RUVLO2

and trips the FAULT latch low, disabling switching. After

VCC rises above VUVLO2, toggling the CHARGE pin reac-

tivates switching.

OVLO2 (Pin 3): VCC Overvoltage Lockout Pin. Senses

when VCC rises above:

VOVLO2 = 1.225+ 50μA•ROVLO2

and trips the FAULT latch low, disabling switching. After

VCC drops below VOVLO2, toggling the CHARGE pin reac-

tivates switching.

FAULT (Pin 4): Open Collector Indication Pin. When either

VTRANS or VCC exceeds the user-selected voltage range, a

transistor turns on. The part will stop switching. This pin

needs a proper pull-up resistor or current source.

DONE (Pin 5): Open Collector Indication Pin. When the

target output voltage (charge mode) is reached, a transis-

tor turns on. This pin needs a proper pull-up resistor or

current source.

CHARGE (Pin 6): Charge Pin. Initiates a new charge cycle

(charge mode) or enables the part (regulation mode)

when driven higher than 1.5V. Bring this pin below 0.3V

to discontinue charging and put the part into shutdown.

Turn-on ramp rates should be between 10ns to 10ms.

CHARGE pin should not be directly ramped with VCC or

LT3751 may not properly initiate.

CLAMP (Pin 7): Internal Clamp Voltage Selection Pin.

Tie this pin to VCC to activate the internal 5.6V gate driver

clamp. Tie this pin to ground to activate the internal 10.5V

gate driver clamp.

FB (Pin 8): Feedback Regulation Pin. Use this pin to achieve

low noise voltage regulation. FB is internally regulated

to 1.22V when a resistive divider is tied from this pin to

the output. FB pin should not ﬂoat. Tie FB pin to either a

resistor divider or ground.

HVGATE Pin Clamp Voltage

vs Temperature

–40

5.70

5.65

5.60

5.55

5.50

100

3751 G18

120

TEMPERATURE (°C)

–20

VCC = 12V

CLAMP = 12V

PIN FUNCTIONS

DCM Trip Voltage (VDRAIN –

VTRANS) vs Temperature (RVTRANS

= RDCM = 25kΩ)

–40

0.64

0.62

0.60

0.58

0.56

0.54

080

3751 G19

120

TEMPERATURE (°C)

VTRANS = 5V

VTRANS = 12V

VTRANS = 24V

VTRANS = 48V

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