L6751B datasheet(10/58 Pages) STMICROELECTRONICS

10 / 58 page

Pin description and connection diagram

L6751B

10/58

Doc ID 024028 Rev 1

SOSC

Oscillator pin.

It allows the switching frequency FSSW to be programmed for the single-

phase section. The pin is internally set to 1.02 V, frequency for single-

phase is programmed according to the resistor connected to GND or VCC

with a gain of 11.5 kHz/µA. Leaving the pin floating programs a switching

frequency of 230 kHz. See Section 10 for details.

SREF

The reference used for the single-phase section regulation is available on

this pin with -125 mV offset. Connect through an RSREF-CSREF to GND to

optimize DVID transitions. Connect through RSOS resistor to the SFB pin to

implement small positive offset to the regulation.

Thermal monitor sensor.

Connect with proper network embedding NTC to the multi-phase power

section. The IC senses the power section temperature and uses the infor-

mation to define the VR_HOT signal and temperature monitoring.

By programming proper TCOMP gain, the IC also implements load-line

and IMON/ILIM thermal compensation for the multi-phase section.

In JMode, the pin disables the single-phase section if shorted to GND.

Pull up to VCC5 with 1 k

Ω to disable the thermal sensor.

See Section 8 for details.

SPWM /

SEN

PWM output.

Connect to single-phase external driver PWM input. During normal opera-

tion the device is able to manage HiZ status by setting and holding the pin

to fixed voltage defined by PWMx strapping.

Connect to VCC5 with 1 k

Ω to disable the single-phase section.

SENDRV

Enable driver.

CMOS output driven high when the IC commands the driver. Used in con-

junction with the HiZ window on the SPWM pin to optimize the single-

phase section overall efficiency. Connect directly to external driver enable

pin.

ILIM

Multi-phase section current limit.

A current proportional to the multi-phase load current is sourced from this

pin. Connect through a resistor RLIM to GND. When the pin voltage

reaches 2.5 V, the overcurrent protection is set and the IC latches. Filter

through CLIM to GND to delay OC intervention.

VR_HOT

Voltage regulator HOT.

Open drain output, this is an alarm signal asserted by the controller when

the temperature sensed through the STM or TM pins exceed TMAX (active

low). See Section 8 for details.

TCOMP

Thermal monitor sensor gain.

Connect proper resistor divider between VCC5 and GND to define the gain

to apply to the signal sensed by the TM to implement thermal compensa-

tion for the multi-phase section. Short to GND to disable temperature com-

pensation (but not thermal sensor). See Section 8 for details.

Table 2.

Pin description (continued)

Pin#

Name

Type

Function

L6751B Datasheet(PDF) 10 Page - STMicroelectronics

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