L6208Q STMicroelectronics, L6208Q Datasheet - Page 18

• Manufacturer Part Number: L6208Q
• Description: Dmos Driver For Bipolar Stepper Motor
• Manufacturer: STMicroelectronics

Circuit description
4.9
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Figure 18. Half step mode
Figure 19. Normal drive mode
Figure 20. Wave drive mode
Non-dissipative overcurrent detection and protection
The L6208 integrates an overcurrent detection circuit (OCD). With this internal over current
detection, the external current sense resistor normally used and its associated power
dissipation are eliminated.
detection circuit.
To implement the over current detection, a sensing element that delivers a small but precise
fraction of the output current is implemented with each high side power MOS. Since this
current is a small fraction of the output current there is very little additional power
dissipation. This current is compared with an internal reference current I
output current reaches the detection threshold (typically 5.6A) the OCD comparator signals
a fault condition. When a fault condition is detected, the EN pin is pulled below the turn off
threshold (1.3V typical) by an internal open drain MOS with a pull down capability of 4mA.
By using an external R-C on the EN pin, the off time before recovering normal operation can
be easily programmed by means of the accurate thresholds of the logic inputs.
Start Up or Reset
Start Up or Reset
Start Up or Reset
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Figure 21
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Doc ID 018710 Rev 1
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D01IN1320
D01IN1321
D01IN1322
shows a simplified schematic of the overcurrent
CLOCK
CLOCK
CLOCK
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I
OUTA
OUTB
I
I
I
I
OUTA
OUTB
OUTA
OUTB
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REF
. When the
L6208Q