DRV8303_15 Datasheet, PDF (24/37 Pages) Texas Instruments – Three Phase Gate Driver

DRV8303
SLOS846B – SEPTEMBER 2013 – REVISED NOVEMBER 2015
www.ti.com
Typical Application (continued)
8.2.1 Design Requirements
Table 13 shows the design parameters for this example.
DESIGN PARAMETER
Supply voltage
Motor winding resistance
Motor winding inductance
Motor poles
Motor rated RPM
Target full-scale current
Sense resistor
MOSFET Q_g
MOSFET RDS(on)
VDS trip level
Switching frequency
Series gate resistance
Amplifier reference
Amplifier gain
8.2.2 Detailed Design Procedure
Table 13. Design Parameters
REFERENCE
PVDD
M_R
M_L
M_P
M_RPM
I_MAX
R_SENSE
Q_g
R_DS(on)
OC_ADJ_SET
ƒ_SW
R_GATE
V_REF
Gain
VALUE
24 V
0.5 Ω
0.28 mH
16 poles
4000 RPM
14 A
0.01 Ω
29 nC
4.7 mΩ
0.123 V
45 kHz
10 Ω
3.3 V
10 V/V
8.2.2.1 Gate Drive Average Current Load
The gate drive supply (GVDD) of the DRV8303 can deliver up to 30 mA (RMS) of current to the external power
MOSFETs. Use Equation 3 to determine the approximate RMS load on the gate drive supply:
Gate Drive RMS Current = MOSFET Qg × Number of Switching MOSFETs × Switching Frequency
(3)
Example:
7.83 mA = 29 nC × 6 × 45 kHz
(4)
This is a rough approximation only.
8.2.2.2 Overcurrent Protection Setup
The DRV8303 provides overcurrent protection for the external power MOSFETs through the use of V_DS monitors
for both the high side and low side MOSFETs. These are intended for protecting the MOSFET in overcurrent
conditions and not for precise current regulation.
The overcurrent protection works by monitoring the V_DS voltage of the external MOSFET and comparing it
against the OC_ADJ_SET register value. If the V_DS exceeds the OC_ADJ_SET value the DRV8303 takes action
according to the OC_MODE register.
Overcurrent Trip = OC_ADJ_SET / MOSFET R_DS(on)
(5)
Example:
26.17 A = 0.123 V/ 4.7 mΩ
(6)
MOSFET R_DS(on) changes with temperature and this will affect the overcurrent trip level.
8.2.2.3 Sense Amplifier Setup
The DRV8303 provides two bidirectional low-side current shunt amplifiers. These can be used to sense a sum of
the three half-bridges, two of the half-bridges individually, or in conjunction with an additional shunt amplifier to
sense all three half-bridges individually.
1. Determine the peak current that the motor will demand (I_MAX). This will be dependent on the motor
parameters and your specific application. I_(MAX) in this example is 14 A.
2. Determine the available voltage range for the current shunt amplifier. This will be ± half of the amplifier
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