Analog Devices Inc. AD7877ACP-500RL7

Overview

AD7877ACP-500RL7 from Analog Devices is a 12-bit successive approximation ADC touch screen controller with integrated 4-wire resistive touch interface, on-chip 2.5 V reference, 8-bit DAC, and dual battery monitor channels (0.5 V to 5 V). It delivers 125 kSPS throughput, supports LCD noise reduction via STOPACQ pin, and operates from 2.7 V to 5.25 V single supply - used in portable medical devices and point-of-sale terminals for precise X/Y position, pressure, and temperature acquisition.

For engineers reviewing the AD7877ACP-500RL7 datasheet, AD7877ACP-500RL7 pinout, AD7877ACP-500RL7 application, or AD7877ACP-500RL7 equivalent, key selection criteria include its 32-lead LFCSP package, 12-bit INL ±2 LSB accuracy, integrated temperature sensor (−40°C to +85°C), GPIO reconfiguration capability (AUX1–AUX3), and SPI-compatible serial interface with DAV/ALERT/PENIRQ interrupt outputs.

Technical Context

The AD7877ACP-500RL7 integrates a track-and-hold ADC with 9:1 analog multiplexer supporting X+, X−, Y+, Y−, TEMP, BAT1, BAT2, AUX1–AUX3, and internal reference routing. Its conversion sequencer enables automatic channel cycling with programmable acquisition time, first-conversion delay, and up to 16-sample averaging per result.

It features three dedicated interrupt outputs (PENIRQ, ALERT, DAV), STOPACQ-controlled acquisition gating to suppress LCD switching noise, and dual-mode 8-bit DAC (voltage or current output) for backlight/contrast control. The device supports both internal 2.5 V reference (±50 ppm/°C tempco) and external reference (1 V to VCC), with separate VDRIVE pin for logic-level flexibility.

Key Specifications

Pinout & Package

AD7877ACP-500RL7 uses a 32-lead LFCSP (5 mm × 5 mm, exposed pad) package. Pin functions are validated per Analog Devices Rev. E datasheet Figure 4 and Table 4.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7843IPWR and MAX11803ETI+, AD7877ACP-500RL7 provides higher functional integration (reference, DAC, temperature, STOPACQ), smaller 32-lead LFCSP footprint, and lower system-level BOM count - reducing total solution size and qualification effort for battery-powered touch interfaces.

Availability

AD7877ACP-500RL7 is available at Aetrix Electronics and suitable for medical tablet interfaces, point-of-sale terminals, smart handheld diagnostic tools, and industrial HMI panels requiring stable component supply, automotive-grade reliability, and long-term production continuity.

Supply support for AD7877ACP-500RL7 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.

The AD7877ACP-500RL7 belongs to Analog Devices' precision data acquisition product line, designed specifically for low-power, high-accuracy touch screen digitization in portable and industrial human-machine interfaces.

FAQ

What is the primary function of the AD7877ACP-500RL7 in a touch-enabled system?

The AD7877ACP-500RL7 serves as a complete 4-wire resistive touch screen controller with integrated 12-bit ADC, on-chip 2.5 V reference, 8-bit DAC, temperature sensor, and dual battery monitor. It acquires X/Y coordinates, touch pressure, ambient temperature, and battery voltages while providing SPI communication and interrupt-driven operation - eliminating need for external reference, DAC, or signal conditioning circuitry in AD7877ACP-500RL7-based designs.

Does the AD7877ACP-500RL7 support external reference voltage, and what is the valid input range?

Yes, the AD7877ACP-500RL7 supports external reference voltage applied to the VREF pin. The valid input range is 1.0 V to VCC, with specified performance guaranteed at 2.5 V. When using external reference, the analog input range becomes 0 V to VREF, and the internal 2.5 V reference must be disabled. This flexibility allows AD7877ACP-500RL7 to maintain accuracy across varying system supply conditions.

How does the STOPACQ pin improve touch measurement accuracy in LCD-based systems?

The STOPACQ pin on the AD7877ACP-500RL7 allows external synchronization of the ADC acquisition phase to avoid periods of high LCD switching noise. When asserted, it halts sampling until noise subsides - reducing position error caused by capacitive coupling from display drivers. This feature is critical for maintaining sub-pixel accuracy in AD7877ACP-500RL7 deployments with fast-refresh LCDs, especially in medical and industrial HMIs.

Can the auxiliary input pins (AUX1–AUX3) on the AD7877ACP-500RL7 be used as general-purpose I/Os?

Yes, pins AUX1 (Pin 6), AUX2 (Pin 5), and AUX3 (Pin 4) on the AD7877ACP-500RL7 are multifunctional: each can operate either as auxiliary analog inputs (ADC channels 3–5) or as configurable GPIOs. Configuration is controlled via GPIO registers in the AD7877ACP-500RL7's internal control register set - enabling dynamic reassignment without hardware change.

What are the power consumption characteristics of the AD7877ACP-500RL7 in different operating modes?

The AD7877ACP-500RL7 draws 650–900 µA in active conversion mode (with internal reference enabled), 150 µA in static mode (ADC powered but idle), and ≤1 µA in shutdown mode. These values are measured at VCC = 3.6 V and confirm suitability for battery-powered applications where AD7877ACP-500RL7 must sustain multi-week operation in sleep states while retaining wake-on-touch responsiveness.