Datasheet

DRV102
11
SBVS009B
www.ti.com
STATUS FLAG
Flag (pin 7) provides fault indication for under-current,
over-current, and thermal shutdown conditions. During a
fault condition, Flag output is driven low (pin voltage
typically drops to 0.2V). A pull-up resistor, as shown in
Figure 7, is required to interface with standard logic. A small
value capacitor may be needed between Flag and ground in
noisy applications.
Figure 7 gives an example of a non-latching fault monitoring
circuit, while Figure 8 provides a latching version. The Flag
pin can sink several milliamps, sufficient to drive external
logic circuitry or an LED (Figure 9) to indicate when a fault
has occurred. In addition, the Flag pin can be used to turn off
other DRV102’s in a system for chain fault protection.
Over/Under Current Fault
An over-current fault occurs when the output current ex-
ceeds the current limit. All units are guaranteed to drive 2A
without current limiting. Typically, units will limit at 2.7A.
The status flag is not latched. Since current during PWM
mode is switched on and off, the flag output will be modu-
lated with PWM timing (see flag waveforms in the Typical
Performance Curves).
An under-current fault occurs when the output current is
below the under-scale current threshold (typically 16mA).
For example, this function indicates when the load is discon-
nected. Again, the flag output is not latched, so an under-
current condition during PWM mode will produce a flag
output that is modulated by the PWM waveform. An initial,
brief under-current flag normally appears driving inductive
loads and may be avoided by adding a parallel resistor
sufficient to move the initial current above the under-current
threshold. Avoid adding capacitance to pin 6 (Out) as it may
cause momentary current limiting.
Over-Temperature Fault
A thermal fault occurs when the die reaches approximately
165°C, producing a similar effect as pulling the input low.
Internal shutdown circuitry disables the output and resets the
Delay Adjust pin. The Flag is latched in the low state (fault
condition) until the die has cooled to approximately 150°C.
A thermal fault can occur in any mode of operation. Recov-
ery from thermal fault will start in delay mode (constant dc
output).
FIGURE 8. Latching Fault Monitoring Circuit.
FIGURE 7. Non-Latching Fault Monitoring Circuit.
DRV102
Thermal Shutdown
Over/Under Current
6
5
7
V
S
Out
4Gnd
5kΩ
Pull-Up
+5V
Flag
TTL or HCT
DRV102
Thermal Shutdown
Over/Under Current
5
7
6
20kΩ
+5V
Flag
Q
Q
CLR
Flag
Flag
Flag Reset
J
CLK
GND K
V
S
74XX76A
(1)
NOTE: (1) Small capacitor (10pF) may be required in noisy environments.
4Gnd
V
S
Out
FIGURE 9. LED to Indicate Fault Condition.
DRV102
Thermal Shutdown
Over/Under Current
7
5kΩ
+5V
Flag
(LED)
HLMP-Q156
5
6
4Gnd
V
S
Out