Tasic Oq0257

Figure 3-12. Reference Voltage Section

The output of an amplifier in the P-ASIC supplies a current to the +1.23V reference source V301 via R307. The +3.3V REFPWM2 voltage is used as reference for the PWMB outputs of the D-ASIC on the Digital part.

The +1.23V REFP voltage is used as main reference source for the reference circuit. This circuit consists of four amplifiers in the T-ASIC, external gain resistors, and filter capacitors.

Amplifier 1 and connected resistors supply the REFPWM1 reference voltage. This voltage is a reference for the PWMA outputs of the D-ASIC on the Digital section. It is also used as reference voltage for the LCD supply on the LCD unit.

Amplifier 2 and connected resistors supply the -1.23 V REFN reference voltage, used for the trigger level voltages TRIGLEV1&2, the C-ASIC POS-A and POS-B voltages, and the C-ASIC OFFSET-A and OFFSET-B voltages. REFN is also the input reference for amplifiers 3 and 4.

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