Datasheet

EXT CAP

AD02

400 Ω

Digital

250 Ω

3.3 V

ADC12 and

CMP

ESD

250 Ω

3.2 kΩ

ESD

AD13

3.3V

SW2

SW1

SW3

3.3 V

ADC12 and

CMP

UCD3138

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SLUSAP2F –MARCH 2012–REVISED NOVEMBER 2013

• AD02 has a special ESD protection mechanism that prevents the pin from pulling down the current-

share bus if power is missing from the UCD3138

The simplified current sharing circuitry is shown in the drawing below:

Figure 4-9. Simplified Current Sharing Circuitry

FOR TEST ONLY,

CURRENT SHARING MODE CS_MODE EN_SW1 EN_SW2 DPWM

ALWAYS KEEP 00

Off or Slave Mode (3-state) 00 00 (default) 0 0 0

PWM Bus 00 01 1 0 ACTIVE

Off or Slave Mode (3-state) 00 10 0 0 0

Analog Bus or Master 00 11 0 1 0

The period and the duty of 8-bit PWM current source and the state of the SW1 and SW2 switches can be

controlled through the current sharing control register (CSCTRL).

4.23 Temperature Reference

The temperature reference register (TEMPREF) provides the ADC12 count when ADC12 measures the

internal temperature sensor (channel 14) during the factory trim and calibration.

This information can be used by different periodic temperature compensation routines implemented in the

firmware. But it should not be overwritten by firmware, otherwise this factory written value will be lost.

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