THV3543_Rev.1.00_E
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Voltage Reference Circuit
Voltage reference circuit generates temperatureꢀcompensated voltage (1.2V) which is used as the internal reference
voltage. Also an external load current (up to 1mA, maximum) can be obtained from VREF pin. Please connect a
capacitor (0.01ꢁF) between VREF pin and SGND for stability.
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VREG5
VREG5 is Builtꢀin 5V local regulator. Please connect an external capacitor (10ꢁF) between VREG5 pin and SGND.
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Oscillator Circuit
Oscillation frequency is internally fixed at 500kHz.
Thermal Shut Down (TSD)
Thermal Shut Down circuit is built in to prevent damages caused by excessive heat. When the junction temperature
reaches 175 °C, TSD circuit stops switching operation and the regulator VREG5 operation. The release temperature is
160°C.
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DC/DC Converter CH-1, CH-2
CHꢀ1 and CHꢀ2 are PWM controllers. CHꢀ1 is for Boost, CHꢀ2 is fixed at 3.3V for Buck. Power MOSFET and Over
Current Detection Circuit are built in. Maximum Duty Cycle ratio of CHꢀ1 LX1 pin is 8.3%, CHꢀ2 LL2 pin is 88%.
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Charge Pump Circuit VGH, VGL
VGH is positive charge pump, and VGL is negative. VGH and VGL also can operate in PFM mode. The duty cycle
ratio of VGH is fixed at 50%, VGL is fixed at 80%.
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VO2_OK, VGH_OK
VO2_OK and VGH_OK are open drain output of the pullꢀdown transistor. When the power supply is turned on, the
transistor is turned on pulling VO2_OK pin and VGH_OK pin to ground level. When each voltage on CHꢀ2 and VGH
reaches 85% of normal output voltage, VO2_OK and VGH_OK are turned off respectively.
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Load Switch Control
LSW_OUT1 pin controls the external PꢀCH MOSFET load switch after normal startꢀup of VGL. Soft start function is
built in.
LSW_OUT2 pin is open drain output. When PG_LOGIC pin is turned High level, pullꢀdown transistor is turned off.
LSW_OUT2 pin can be used as the external NꢀCH MOSFET load switch controller or level shifter.
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Operational Amplifier
Operational amplifier is used for Vcom or Half AVDD. Use an external bipolar transistor when large output current
is required.
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LDO
LDO have builtꢀin recovery type current limiting protection. The load current capacity is within 250mA. The output
voltage is set by external resistance (See “Output Voltage Setting (LDO)”).
THine Electronics, Inc.
Copyright© 2011 THine Electronics, Inc.
12/19
THINE [ THINE ELECTRONICS, INC. ]
