AMC7812SPAPR datasheet(43/92 Pages) TI

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DAC

Latch

DAC

CLR-nBitinHW-DAC-CLR- Register

ACLR- Bit

AlarmSource

DAC

CLR-Setting

CLR-nBitinSW-DAC-CLR- Register

DAC-CLR-n Pin

DAC

DataRegister

AMC7812

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SBAS513E – JANUARY 2011 – REVISED SEPTEMBER 2013

Clear DACs

DAC-n can be cleared using hardware or software as shown in Figure 93. When DAC-n goes to a clear state, it

is immediately loaded with predefined code in the DAC-n-CLR-Setting Register, and the output is set to the

corresponding level to shut down the external LDMOS device. However, the DAC-DATA-n Register does not

change. When the DAC goes back to normal operation, DAC-n is immediately loaded with the previous data from

the DAC-DATA-n Register and the output of DAC-n-Out is set back to the previous level to restore LDMOS to the

status before shutdown, regardless of the SLDAC-n bit status.

Figure 93. Clearing DAC-n

The AMC7812 is implemented with two external control lines, the DAC-CLR-0 and DAC-CLR-1 pins, to clear the

DACs. When either pin goes low, the corresponding user-selected DACs are in a cleared state. The HW_DAC-

CLR-0 Register determines which DAC is cleared when the DAC-CLR-0 pin is low. The register contains 12 clear

bits (CLR-n), one per DAC. If the CLR-n bit = '1', DAC-n is in a cleared state when the DAC-CLR-0 pin is low.

However, if the CLR-n bit = '0', DAC-n does not change when the pin is low. Likewise, the HW-DAC-CLR-1

Writing directly to the SW_DAC_CLR Register puts the selected DACs in a cleared state. DACs can also be

forced into a clear state by alarm events. The AUTO-DAC-CLR-SOURCE Register specifies which alarm events

force the DACs into a clear state, and the AUTO-DAC-CLR-EN Register defines which DACs are forced into a

clear state. Refer to the AUTO-DAC-CLR-SOURCE and AUTO-DAC-CLR-EN Registers for further details.

DAC Output Thermal Protection

A significant amount of power can be dissipated in the DAC outputs. The AMC7812 is implemented with a

thermal protection circuit that sets the THERM-ALR bit in the Status Register if the die temperature exceeds

+150°C. The THERM-ALR bit can be used in combination with THERM-ALR-CLR (bit 2 in the AUTO-DAC-CLR-

SOURCE Register) and ACLR-n (bits[14:3] in the AUTO-DAC-CLR-EN Register) to set the DAC output to a

predefined code when this condition occurs. Note that this feature is disabled when the local temperature sensor

powers down.

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AMC7812SPAPR Datasheet(PDF) 43 Page - Texas Instruments