The ADS7843 is a 12-bit sampling analog-to-digital con-

verter (ADC) used to drive 4-wire touch-screens to serial

interfaces by ratiometrically converting two differential in-

put signals. The ADS7843 also produces an accurate output

with the first conversion cycle once powered up. Because of

this feature, the ADC can be powered up and down continu-

ously, thus, enabling designers to conserve energy in low

power applications such as Personal Digital Assistants (PDA),

where the number of conversions is limited but a fast and

accurate response is required on the first conversion. To

maximize energy conservation, the ADS7843 incorporates a

Pen Interrupt Request feature (PENIRQ), which enables

designers to fully control the power-down operation when

interfacing with Micoprocessors (MPU). Figure 1 is a sim-

plified flow diagram for a PDA showing how PENIRQ is

used to assist in controlling power-down operations.-The ADS7843　is　a　12-bit　sampling　analog-to-digital　con-

verter　(ADC)　used　to　drive　4-wire　touch-screens　to　serial

interfaces by ratiometrically converting two differential in-

put signals. The ADS7843 also produces an accurate output

with the first conversion cycle once powered up. Because of

this feature, the ADC can be powered up and down continu-

ously,　thus,　enabling　designers　to　conserve　energy　in　low

power applications such as Personal Digital Assistants (PDA),

where the number of conversions is limited but a fast and

accurate　response　is　required　on　the　first　conversion.　To

maximize energy conservation, the ADS7843 incorporates a

Pen　Interrupt　Request　feature　(PENIRQ),　which　enables

designers to fully control the power-down operation when

interfacing with Micoprocessors (MPU). Figure 1 is a sim-

plified flow diagram for a PDA showing how PENIRQ is

used to assist in controlling power-down operations.