STDRIVE102BHTR datasheet(19/56 Pages) STMICROELECTRONICS

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Figure 10. Charge pump output voltage with respect to the load current

Load Current [mA]

VS = VM = VCC = 7 V

VS = VM = VCC = 12 V

VS = VM > 15 V

5.2

Gate drivers

The gate drivers use a constant-current approach enabling the following advantages:

•

No external components are required between the MOSFETs’ gates and the drivers.

•

The slew rate of the half-bridge outputs is better controlled.

The high-side drivers (Figure 11) and the low-side drivers (Figure 12) have a similar structure:

•

A reference pin for the low level (OUTx for the high-side and SLSx for the low-side).

•

The output pin (GHSx for the high-side or GLSx for the low-side), which directly drives the external

MOSFET’s gate.

•

The supply pin (VBOOT in common to the three high side drivers and VCC in common to the three low side

drivers).

When the driver is not operative (for example, in standby mode or for very low supply), an equivalent 100 kΩ

resistor keeps the external MOSFETs off. In normal conditions, the gate driver must force a voltage on the gate of

its respective MOSFET, in order to keep it in a well-defined state. This datasheet adopts the following definitions:

•

Setting HIGH the gate driver means that the driver sources a controlled current to increase the VGS of the

MOSFET and turn it on. The gate current comes from the supply VCC in case of the low-side driver or from

VBOOT in case of the high-side driver.

•

Setting LOW the gate driver means that the driver sinks a controlled current from the gate of the MOSFET

to turn it off. The sink circuitry of the driver is referred to the OUTx pin for the high-side, and to the SLSx pin

for the low-side. This approach ensures that the MOSFET is kept off, even in the presence of below-GND

transients.

In normal mode operation, when a high-side driver is set HIGH, the voltage on the GHSx pin increases up to its

target level VBOOT . At the same time the OUTx voltage increases up to VM, so that the VGS of the external

MOSFET is kept under control (less or equal to VCC). In case the OUTx pin cannot follow the GHSx pin, the gate

driver protects the gate of the external MOSFET from breakdown clamping the VGS at VGS, clamp.

The six gate drivers (three low-side and three high-side) are controlled by six digital inputs, INH1/IN1, INH2/IN2,

INH3/IN3, INL1/EN1, INL2/EN2, INL3/EN3. Each digital input has an internal pull-down resistor RPD,in. Each half-

bridge (driven by a low-side driver and a high-side driver) is controlled by a couple of inputs: for example,

INH1/IN1 and INL1/EN1 refer to half-bridge 1. The label INHx/INx or INLx/ENx can be used to indicate one of the

three half-bridges, with no specific reference to a particular channel. Note that the terms “channel” or “phase”

could be used similarly to refer to the half-bridge output.

STDRIVE102BH, STDRIVE102H

Device description

DS14545 - Rev 1

page 19/56

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