DRV8302 Datasheet, PDF (12/21 Pages) Texas Instruments – Three Phase Pre-Driver with Dual Current Shunt Amplifiers and Buck Regulator – Hardware Controlled

DRV8302
SLES267 – AUGUST 2011
200 kW
S2
DC_CAL
SN
DC_CAL
SP
DC_CAL
50 kW
5 kW
_
S1
AVDD
5 kW
+
50 kW
S1
200 kW
S2
REF
50 kW
50 kW
_
AVDD
+
100 W
SO
Vref /2
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Figure 2. Current Shunt Amplifier Simplified Block Diagram
BUCK CONVERTER
Although integrated in the same device, buck converter is designed completely independent of rest of the gate
driver circuitry. Since buck will support external MCU or other external power need, the independency of buck
operation is very critical for a reliable system; this will give buck minimum impact from gate driver operations.
Some examples are: when gate driver shuts down due to any failure, buck will still operate unless the fault is
coming from buck itself. The buck keeps operating at much lower PVDD of 3.5V, this will assure the system to
have a smooth power up and power down sequence when gate driver is not able to operate due to a low PVDD.
The buck has an integrated high side n-channel MOSFET. To improve performance during line and load
transients the device implements a constant frequency, current mode control which reduces output capacitance
and simplifies external frequency compensation design.
The wide switching frequency of 450kHz to 720kHz allows for efficiency and size optimization when selecting the
output filter components. The switching frequency is adjusted using a resistor to ground on the RT_CLK pin.
The buck converter has a default start up voltage of approximately 2.5V. The EN_BUCK pin has an internal
pull-up current source that can be used to adjust the input voltage under voltage lockout (UVLO) threshold with
two external resistors. In addition, the pull up current provides a default condition. When the EN_BUCK pin is
floating the device will operate. The operating current is 116µA when not switching and under no load. When the
device is disabled, the supply current is 1.3µA.
The integrated 200mΩ high side MOSFET allows for high efficiency power supply designs capable of delivering
1.5 amperes of continuous current to a load. The bias voltage for the integrated high side MOSFET is supplied
by a capacitor on the BOOT to PH pin. The boot capacitor voltage is monitored by an UVLO circuit and will turn
the high side MOSFET off when the boot voltage falls below a preset threshold. The buck can operate at high
duty cycles because of the boot UVLO. The output voltage can be stepped down to as low as the 0.8V
reference.
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