at1736 Aimtron Technology, at1736 Datasheet - Page 14

• Manufacturer Part Number: at1736
• Description: Lcd Panel Power Supplies With High-current Operational Amplifiers
• Manufacturer: Aimtron Technology

Output Voltage Fault Protection
After soft-start period, if the feedback voltage of the step-up DC-DC converter or any
of the linear regulators does not exceed its fault-detection threshold, the AT1736
enables the internal fault timer. If the fault condition exceeds the fault-timer duration
(200ms typical), then the AT1736 shuts down all the outputs except the reference.
Once the fault condition is removed, cycle the input voltage (below the UVLO falling
threshold) to reactivate the chip.
Reference Voltage
The reference output voltage is typical 1.233V and the source ability is at least 50µA.
Connecting a 0.22µF bypass ceramic capacitor between REF and GND is
recommended.
Gate-On Pulse Modulator
The AT1736 includes a gate-on pulse modulator to control gate-on voltage waveform
to reduce the flicker on TFT LCD panel. After the V
soft-start periods are complete, fault conditions do not exist, and the V
turn-on threshold, the gate-on pulse modulator start to be active and is controlled by
SWCTL. There are two high voltage switches Q1 and Q2 connecting to GON.
Another terminal of Q1 is connected to positive charge-pump output for the positive
high voltage input (VPSRC), and Q2 is connected to DRN with an external series
resistor to ground for discharging the positive gate-on voltage. If SWCTL is high, Q1
turns on and Q2 turns off. If SWCTL is low, Q1 turns off and Q2 turns on.
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: [phone]
10/19/2007 REV:0.5
Fax: [phone]
Figure 3. Gate-on pulse modulator
14
High-Current Operational Amplifiers
Preliminary Product Information
LCD Panel Power Supplies with
WWW:
IN
Email:
exceeds UVLO, all the
http://www.aimtron.com.tw
[e-mail]
DLP
exceeds the
AT1736