The ADS7845 is a 12-bit sampling analog-to-digital converter (ADC) with a synchronous serial interface and low on-resistance switches for driving touch screens. Typical power dissipation is 750µW at a 125kHz throughput rate and a +2.7V supply. The reference voltage (VREF) can be varied between 1V and +VCC, providing a corresponding input voltage range of 0V to VREF. The device includes a shutdown mode which reduces typical power dissipation to under 0.5µW. The ADS7845 is guaranteed down to 2.7V operation. Low power, high speed, and on-board switches make the ADS7845 ideal for battery-operated systems such as personal digital assistants with resistive touch screens and other portable equipment. The ADS7845 is available in a 16-lead SSOP package and is guaranteed over the –40°C to +85°C temperature range.
The ADS7845 is a 12‑bit successive‑approximation ADC designed for resistive touch‑screen interfaces. It operates from a single 2.0 V to 5.25 V supply, offers programmable 8‑ or 12‑bit resolution, and includes on‑chip panel drivers and auxiliary analog inputs. Typical power dissipation is 750 µW at 125 kHz, dropping below 0.5 µW in shutdown mode.
The device is supplied in a 16‑lead SSOP package and is rated for operation from –40 °C to +85 °C. It provides a serial interface with configurable control bits, supports ratiometric conversion, and includes protection features such as full power‑down control and ESD sensitivity handling.
| Resolution | 12 Bits |
|---|---|
| Capacitance | 25 pF |
| Leakage Current | 0.1 µA |
| Integral Linearity Error | +2 LSB |
| Offset Error | +6 LSB |
| Gain Error | 4 LSB |
| Noise | 30 µV rms |
| Power Supply Rejection Ratio | 70 dB |
| Conversion Time | 12 Clock Cycles |
| Acquisition Time | 3 Clock Cycles |
| Throughput Rate | 125 kHz |
| Multiplexer Settling Time | 500 ns |
| Aperture Delay | 30 ns |
| Aperture Jitter | 100 ps |
| Channel‑to‑Channel Isolation | 100 dB |
| On‑Resistance (UL, UR) | 7 Ω |
The ADS7845 operates from a single supply of 2.0 V to 5.25 V.
The device can sample at up to 125 kHz.
In shutdown mode the typical power dissipation is under 0.5 µW.
It provides a programmable resolution of either 8‑ or 12‑bits; the default is 12‑bits.