DRV8301 Datasheet, PDF (13/26 Pages) Texas Instruments – Three Phase Pre-Driver with Dual Current Shunt Amplifiers and Buck Regulator

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DC_CAL
SN
DC_CAL
SP
DC_CAL
400 kW
200 kW
100 kW
50 kW
5 kW
_
S4
S3
S2
S1
AVDD
5 kW
+
50 kW
S1
100 kW
S2
200 kW
S3
400 kW
S4
REF
50 kW
50 kW
_
AVDD
+
DRV8301
SLOS719 – AUGUST 2011
100 W
SO
Vref /2
Figure 4. 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 300kHz to 2200kHz 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 device has an internal phase lock loop (PLL) on the RT_CLK pin that is used to synchronize the power
switch turn on to a falling edge of an external system clock.
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.
Copyright © 2011, Texas Instruments Incorporated
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