DRV2604L Datasheet, PDF (19/73 Pages) Texas Instruments – DRV2604L 2- to 5.2-V Haptic Driver for LRA and ERM with Internal Memory and Smart-Loop Architecture

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DRV2604L
SLOS866D – MAY 2014 – REVISED JUNE 2015
Feature Description (continued)
8.3.11 I²C Watchdog Timer
If an I²C stops unexpectedly, the possibility exists for the I²C protocol to remain in a hanged state. To allow for
the recovery of the communication without having to power cycle the device, the DRV2604L device includes an
automatic watchdog timer that resets the I²C protocol without user intervention after 4.33 ms. This behavior
happens in all conditions except in standby mode. If the I²C stops unexpectedly during standby mode, the only
way to recover communication is by power-cycling the device.
8.3.12 Device Protection
8.3.12.1 Thermal Protection
The DRV2604L device has thermal protection that causes the device to shut down if it becomes too hot. In the
event where the thermal protection kicks in, the DRV2604L device asserts a flag (bit OVER_TEMP in register
0x00) to notify the host processor.
8.3.12.2 Overcurrent Protection of the Actuator
If the impedance at the output pin of the DRV2604L device is too low, the device latches the over-current flag
(OC_DETECT bit in register 0x00) and shuts down. The device periodically monitors the status of the short and
remains in this condition until the short is removed. When the short is removed, the DRV2604L device restarts in
the default state.
8.3.12.3 Overcurrent Protection of the Regulator
The DRV2604L device has an internal regulator that powers a portion of the system. If a short occurs at the
output of the REG pin, an internal overcurrent protection circuit is enabled and limits the current.
During a REG short, the device is not functional. When the short is removed, the DRV2604L device automatically
resets to default conditions.
8.3.12.4 Brownout Protection
The DRV2604L device has on-chip brownout protection. When activated, a reset signal is issued that returns the
DRV2604L device to the initial default state. If the regulator voltage V_(REG) goes below the brownout protection
threshold (V_(BOT)) the DRV2604L device automatically shuts down. When V_(REG) returns to the typical output
voltage (1.8 V) the DRV2604L device returns to the initial device state. The brownout protection threshold
(V_(BOT)) is typically at 0.84 V.
The previously described behavior has one exception. The brownout circuit is designed to tolerate fast brownout
conditions as shown by Case 1 in Figure 15. If the V_DD ramp-up rate is slower than 3.6 kV/s, then the device can
fall into an unknown state. In such a situation, to return to the initial default state the device must be power-
cycled with a V_DD ramp-up rate that is faster than 3.6 kV/s.
V_DD
2V
1.8 V
Case 1
Return to
default
state
Case 2
Case 3
Unknown
state
Unknown
state
Case 4
Return to
default
state
V_DD
REG
V_(BOT)
0V
Slew rate > 3.6 kV/s
Slew rate < 3.6 kV/s
Slew rate < 3.6 kV/s
Figure 15. Brownout Behavior
Slew rate > 3.6 kV/s
Time
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