Analog Devices Inc. AD7879ACPZ-RL

Overview

AD7879ACPZ-RL from Analog Devices is a 12-bit SAR ADC touch screen controller for 4-wire resistive touch panels, operating from 1.6 V to 3.6 V, featuring median + averaging noise filtering, touch-pressure measurement, and 105 kSPS throughput. It integrates low-R_ON switch drivers (X+/Y+ ≤6 Ω), auxiliary ADC input (0.5–5 V), and programmable GPIO/INT/PENIRQ functionality - deployed in handheld medical devices and point-of-sale terminals.

For engineers reviewing the AD7879ACPZ-RL datasheet, AD7879ACPZ-RL pinout, AD7879ACPZ-RL application, or AD7879ACPZ-RL equivalent, key selection considerations include its WLCSP-12 package, SPI-only interface (no I²C), 6 μA shutdown current, ±3 LSB INL, and integrated temperature sensing with ±2°C accuracy over −40°C to +85°C.

Technical Context

The AD7879ACPZ-RL implements a synchronous serial (SPI) interface with dedicated CS, DIN, DOUT, and SCL pins, and uses an internal 2 MHz clock (±10% tolerance) to drive its 12-bit SAR ADC. Its analog front-end includes a 6-to-1 multiplexer routing X+, X−, Y+, Y−, AUX/VBAT/GPIO, and temperature sensor to the ADC core.

Conversion sequencing is fully programmable via on-chip control registers: acquisition time, first-conversion delay, number of averages (up to 16), and filter mode (median only, average only, or both) are all user-configurable. The device supports standalone (master) or host-controlled (slave) operation and provides three interrupt modes - PENIRQ, INT (limit-exceeded), and DAV (data available) - on a single shared pin.

Key Specifications

Pinout & Package

AD7879ACPZ-RL is housed in a 12-ball, 1.6 mm × 2 mm wafer-level chip-scale package (WLCSP) with bottom-side ball layout and exposed die pad recommended for grounding. Pin functions are validated per Analog Devices Rev. D datasheet Figures 5 and Table 6.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar touch screen controller applications.

Compared with AD7879ACPZ-RL, AD7879ARMZ offers better thermal performance in high-power-density layouts but increases board area by 4.4×; TSC2007IPWR trades SPI flexibility and integrated temperature sensing for simplified I²C integration - neither is pin-compatible, and both require PCB redesign and firmware adaptation.

Availability

AD7879ACPZ-RL is available at Aetrix Electronics and suitable for medical handhelds, point-of-sale terminals, and portable test equipment requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant WLCSP packaging.

Supply support for AD7879ACPZ-RL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide and ISO 9001-certified manufacturing.

The AD7879ACPZ-RL belongs to Analog Devices' precision touch controller product line, engineered specifically for low-voltage, low-power 4-wire resistive touch screen interfaces in space- and energy-constrained portable electronics.

FAQ

What interface protocol does the AD7879ACPZ-RL support?

The AD7879ACPZ-RL supports SPI only - it is the non-I²C variant of the AD7879 family (denoted by absence of ADD0/ADD1 pins and presence of CS, DIN, DOUT). Unlike AD7879-1, AD7879ACPZ-RL lacks I²C capability and requires a 4-wire SPI master with dedicated chip select. Its timing complies with Table 2 in Rev. D datasheet (fSCL ≤5 MHz).

Does the AD7879ACPZ-RL include an internal temperature sensor?

Yes, the AD7879ACPZ-RL integrates an on-die temperature sensor with ±2°C accuracy over −40°C to +85°C, calibrated at 25°C. Temperature data is read from dedicated result registers (address 0x0A) and can be used for ambient compensation of touch coordinates or system thermal management - no external sensor required.

What is the maximum allowable voltage on the AUX/VBAT/GPIO pin of the AD7879ACPZ-RL?

The AUX/VBAT/GPIO pin of the AD7879ACPZ-RL accepts 0.5 V to 5 V when configured as battery monitor (VBAT mode), per Table 1 in the datasheet. Absolute maximum rating is −0.3 V to +5 V (Table 4); exceeding 5 V risks permanent damage. In GPIO mode, it operates at VCC logic levels with ±0.1 µA leakage.

Can the AD7879ACPZ-RL measure touch pressure, and how is it implemented?

Yes, the AD7879ACPZ-RL supports touch-pressure measurement by calculating contact resistance between X and Y layers using sequential X-layer and Y-layer voltage measurements. This is performed automatically in dedicated pressure-measurement mode (Control Register 1, bit[11]=1) and requires no external components - results are stored in the pressure result register (0x09).

What package type and dimensions does the AD7879ACPZ-RL use?

The AD7879ACPZ-RL uses a 12-ball, 1.6 mm × 2 mm wafer-level chip-scale package (WLCSP) with 0.5 mm pitch and bottom-side solder balls. The exposed thermal pad is not internally connected but must be soldered to the PCB ground plane per datasheet Figure 5 and layout recommendations to ensure thermal reliability and mechanical stability.