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4. TROUBLE SHOOTING
4.22 Vibrator
The PM7540 IC supports silent incoming-call alarms with its vibration motor driver. The vibration
driver is a programmable voltage output that is referenced to VDD; when off, its output voltage is
VDD. The motor is connected between VDD and pin N2 (VIB_DRV_N); the voltage across the motor
is Vm = VDD - Vout where Vout is the PM7540 IC voltage at pin N2.
A flyback diode is connected across the motor terminals to prevent inductive kickback during turn-off
and suppress voltage transients that could damage the IC. Short circuit current limiting is also
provided to limit the current when the motor is stalled or shorted. The driver is programmable from
1.2 to 3.1 V in 100-mV increments.
LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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