DRV8830_16 Datasheet, PDF (10/22 Pages) Texas Instruments – Low-Voltage Motor Driver With Serial Interface

DRV8830
SLVSAB2G – MAY 2010 – REVISED DECEMBER 2015
www.ti.com
Feature Description (continued)
VSET[5..0]
0x10h
0x11h
0x12h
0x13h
0x14h
0x15h
0x16h
0x17h
0x18h
0x19h
0x1Ah
0x1Bh
0x1Ch
0x1Dh
0x1Eh
0x1Fh
Table 1. Commanded Output Voltage (continued)
OUTPUT VOLTAGE
1.29
1.37
1.45
1.53
1.61
1.69
1.77
1.85
1.93
2.01
2.09
2.17
2.25
2.33
2.41
2.49
VSET[5..0]
0x30h
0x31h
0x32h
0x33h
0x34h
0x35h
0x36h
0x37h
0x38h
0x39h
0x3Ah
0x3Bh
0x3Ch
0x3Dh
0x3Eh
0x3Fh
OUTPUT VOLTAGE
3.86
3.94
4.02
4.1
4.18
4.26
4.34
4.42
4.5
4.58
4.66
4.74
4.82
4.9
4.98
5.06
The voltage can be calculated as 4 x VREF x (VSET +1) / 64, where VREF is the internal 1.285-V reference.
7.3.3 Current Limit
A current limit circuit is provided to protect the system in the event of an overcurrent condition, such as what
would be encountered if driving a DC motor at start-up or with an abnormal mechanical load (stall condition).
The motor current is sensed by monitoring the voltage across an external sense resistor. When the voltage
exceeds a reference voltage of 200 mV for more than approximately 3 µs, the PWM duty cycle is reduced to limit
the current through the motor to this value. This current limit allows for starting the motor while controlling the
current.
If the current limit condition persists for some time, it is likely that a fault condition has been encountered, such
as the motor being run into a stop or a stalled condition. An overcurrent event must persist for approximately
275 ms before the fault is registered. After approximately 275 ms, a fault signaled to the host by driving the
FAULTn signal low and setting the FAULT and ILIMIT bits in the serial interface register. Operation of the motor
driver will continue.
The current limit fault condition is cleared by setting both IN1 and IN2 to zero to disable the motor current, by
putting the device into the shutdown state (IN1 and IN2 both set to 1), by setting the CLEAR bit in the fault
register, or by removing and re-applying power to the device.
The resistor used to set the current limit must be less than 1 Ω. Its value may be calculated as follows:
200 mV
R=
ISENSE
¾ _I
LIMIT
where
• R_ISENSE is the current sense resistor value.
• I_LIMIT is the desired current limit (in mA).
(1)
If the current limit feature is not needed, the ISENSE pin may be directly connected to ground.
7.3.4 Protection Circuits
The DRV8830 is fully protected against undervoltage, overcurrent and overtemperature events. A FAULTn pin is
available to signal a fault condition to the system, as well as a FAULT register in the serial interface that allows
determination of the fault source.
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