DRV8305_15 Datasheet, PDF (19/53 Pages) Texas Instruments – DRV8305 Three Phase Gate Driver With Current Shunt Amplifiers and Voltage Regulator

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DRV8305
SLVSCX2A – AUGUST 2015 – REVISED SEPTEMBER 2015
The gate driver is implemented as constant current sources for up to 80 mA (sink)/70 mA (source) currents in
order to maintain the accuracy required for precise slew rate control. Beyond that, resistors are switched to
create the desired settings up to 1.25 A (sink)/1 A (source).
7.3.5 IDRIVE/TDRIVE
The DRV8305 gate driver has an integrated state machine (TDRIVE/IDRIVE scheme) to protect against high
current events on the outputs (shorts or inadvertent clamp activation) and also dV/dt turn on due to switching on
the phase nodes.
When changing the state of the gate driver, the peak current (source or sink, IDRIVE) is applied for a fixed period
of time (TDRIVE) until the gate capacitances are charged or discharged completely. After this time has expired, a
fixed current source of I_HOLD is used to hold the gate at the desired state (pulled up or pulled down).
INHX
GHX (V)
tDRIVEP
tDRIVEN
GHX (mA)
-IPULLDOWN
IDRIVEP
IHOLD
-IHOLD
IDRIVEN
-IPULLDOWN
tDEAD
GLX (mA) ^IHOLD
- IHOLD
IDRIVEN
tDRIVEN
GLX
-IPULLDOWN
IDRIVEP
`
IHOLD
tDRIVEP
INLX
Figure 7. TDRIVE/IDRIVE Waveforms
This fixed TDRIVE time ensures that under abnormal circumstances like a short on the FET gate, or the
inadvertent turning on of a FET V_GS clamp, the high peak current through the DRV8305 gate drivers is limited to
the energy of the peak current during TDRIVE. Limiting this energy helps to prevent the gate driver from
damage.
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