DRV8302_16 Datasheet, PDF (14/32 Pages) Texas Instruments – Three Phase Gate Driver

DRV8302
SLES267C – AUGUST 2011 – REVISED MARCH 2016
www.ti.com
7.3.2 Current Shunt Amplifiers
The DRV8302 includes two high performance current shunt amplifiers to accurate low-side, inline current
measurement.
The current shunt amplifiers have 2 programmable GAIN settings through the GAIN pin. These are 10, and 40
V/V.
They provide output offset up to 3 V to support bidirectional current sensing. The offset is set to half the voltage
on the reference pin (REF).
To minimize DC offset and drift overtemperature, a calibration method is provided through either the DC_CAL
pin. When DC calibration is enabled, the device shorts the input of the current shunt amplifier and disconnect the
load. DC calibration can be done at any time, even during MOSFET switching, since the load is disconnected.
For the best results, perform the DC calibration during the switching OFF period, when no load is present, to
reduce the potential noise impact to the amplifier.
The output of current shunt amplifier can be calculated as:
V_O = ^VREF - G ´ (SN_X - SP_X )
2
where
• VREF is the reference voltage (REF pin)
• G is the gain of the amplifier (10 or 40 V/V)
• SNX and SPx are the inputs of channel x
(1)
SPx should connect to resistor ground for the best common mode rejection.
Figure 4 shows current amplifier simplified block diagram.
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
Figure 4. Current Shunt Amplifier Simplified Block Diagram
14
Submit Documentation Feedback
Product Folder Links: DRV8302
Copyright © 2011–2016, Texas Instruments Incorporated