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DRV8702D-Q1 Datasheet, PDF (49/66 Pages) Texas Instruments – Automotive Half-Bridge Gate Driver
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DRV8702D-Q1, DRV8703D-Q1
SLVSDX8 – MARCH 2017
If the gate-to-drain charge is 2.3 nC and the desired rise time is around 100 to 300 ns, use Equation 7 to
calculate the minimum IDRIVE (IDRIVE1) and Equation 8 to calculate the maximum IDRIVE (IDRIVE2).
IDRIVE1 = 8.4 nC / 100 ns = 84 mA
(7)
IDRIVE2 = 8.4 nC / 300 ns = 28 mA
(8)
Select a value for IDRIVE between 28 and 84 mA. An IDRIVE value of approximately 50 mA for the source
(approximately 100 mA sink) was selected for this application. This value requires a 200-kΩ resistor from the
IDRIVE pin to ground.
8.2.2.3 VDS Configuration
The VDS monitor is configured based on the maximum current and RDS(on) of the FETs. The VDS pin of the
DRV8702D-Q1 selects the VDS monitor trip threshold. Use Equation 3 to calculate the trip current.
IVDS
!
VVDS
RDS(on)
(9)
If the RDS(on) of the FET is 1.8 mΩ and the desired VDS trip is less than 100 A, the VVDS voltage is equal to 180
mV as shown in Equation 10.
VVDS = IVDS × RDS(on) = 100 A × 1.8 mΩ = 180 mV
(10)
Select a value for the VDS voltage that less than 180 mV. A VVDS value of 0.12 V was selected for ths
application. This value requires tying the VDS pin to ground.
8.2.2.4 Current Chopping Configuration
The chopping current is set based on the sense resistor value and the analog voltage at the VREF pin. Use
Equation 11 to calculate the current (I(CHOP)). The amplifier gain, AV, is 19.8 V/V for the DRV8702D-Q1 and VIO is
typically 2.5 mV (input referred).
I(CHOP)
VVREF VIO
AV u R(SENSE)
(11)
For example, if the desired chopping current is 15 A, select a value of 10 mΩ for R(SENSE). The value of VVREF
must therefore be 3.05 V. Add a a resistor divider from the AVDD (5 V) pin to set the VVREF at approximately 3.05
V. Select a value of 13 kΩ for and 20 kΩ for R1.
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