LC79451KB Datasheet, PDF (20/38 Pages) ON Semiconductor – Controller and Driver

LC79451KB
6-4. Automatic Switching Function of Charge-pump Frequency
This device can set charge-pump frequency of each state to reduce consumption. When a state changes, charge-pump
frequency is changed automatically. Please set charge-pump frequency by each load.
Charge-pump rising period
Waveform output standby period
Waveform output period
⇒ 32kHz
⇒ Select from 1kHz, 2kHz, 4kHz, 8kHz, 16kHz, 32kHz
⇒ Select from 4kHz, 8kHz, 16kHz, 32kHz
6-5. Setting Function of Charge-pump References Voltage
This device can set charge-pump reference voltage to reduce consumption by the use range of the power supply
voltage.
When VDD2 is more over 2.7V, we recommend setting 2.5V to reference voltage.
Charge-pump reference voltage 1.25V
VDD2 active range : 1.8V to 3.6V
+/-15V are generated from 1.25V multiplied by 12.
Charge-pump reference voltage 2.50V
VDD2 active range : 2.7V to 3.6V
+/-15V are generated from 2.5V multiplied by 6.
6-6. Automatic Discharge Function and the Change of Image Function after Power Off
After VDD power off, when stored electric charge is left to the external capacitor, the image may be changed.
Therefore this device is equipped with a function (cf. 10-3) to discharge stored electric charge. When stored electric
charge is not discharged, discharge is performed automatically if the following condition is met.
Condition for automatic discharge
♦ VOUT0 ≥ 2.0V, VOUT1 ≥ 4.0V, VOUT2 ≥ 10V, VOUT3 ≤ -10V
♦ Charge-pump stop
♦ VDD voltage falls to 0.3V within one second
In addition, you can display full screen black by automatic discharge in the following setting and condition.
Setting and condition of full screen black image
♦ Full screen black image setting of automatic discharge (control register 2: OFFBLK = 1)
♦ The voltage level of RESET keeps VDD
♦ VOUT0 ≥ 2.0V, VOUT1 ≥ 4.0V, VOUT2 ≥ 10V, VOUT3 ≤ -10V
♦ Charge-pump stop
♦ VDD voltage falls to 0.3V within one second
Notice : During setting full screen black image function, all segment pin output VOUT2.
VOUT2 output continues until to VDD and VOUT1 raise to some extent, or VOUT2 voltage is discharged
naturally. When the panel shows abnormality by applying it for the long time, please do not use it.
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