Analog Devices Inc. AD7575BQ

Overview

AD7575BQ from Analog Devices is an 8-bit successive approximation analog-to-digital converter (ADC) with integrated track-and-hold, designed for unipolar single-supply operation at +5 V. It achieves a 5 µs conversion time using a 4 MHz external clock, supports 0 to +2.46 V input range (with +1.23 V reference), delivers ±1/2 LSB total unadjusted error, and interfaces directly to 8-bit microprocessors including Z80H, 8085A-2, and TMS32010 via CS/RD control logic.

For engineers reviewing the AD7575BQ datasheet, AD7575BQ pinout, AD7575BQ application, or AD7575BQ equivalent, key selection criteria include its industrial temperature range (–25°C to +85°C), on-chip track/hold enabling full-scale 50 kHz signal digitization, 100 ns data access time, 15 mW typical power dissipation, and compatibility with slow-memory or ROM-style microprocessor interfaces.

Technical Context

The AD7575BQ implements a SAR architecture with internal clock division (÷2) and samples the analog input on the third falling edge of CLK after CS and RD assertion. Its LC2MOS process enables low-power CMOS operation while maintaining high-speed performance and built-in track/hold functionality requiring no external hold capacitor.

Conversion timing is deterministic: 20 input clock cycles (10 internal cycles) per conversion, with BUSY signaling active-low during acquisition and conversion. The device supports both internal RC-generated and external TTL/CMOS clock sources, and its three-state latched outputs allow direct connection to shared microprocessor data buses without additional buffering.

Key Specifications

Pinout & Package

The AD7575BQ is supplied in a hermetically sealed Cerdip (Ceramic Dual In-line Package) with 18 leads, designated Q-18 per Analog Devices' ordering guide. Pin 1 identifier is marked on top surface; TP must be hard-wired HIGH for normal operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit ADC applications.

Compared with AD7575AQ and MAX160BCNG+, the AD7575BQ provides superior linearity (±1/2 LSB), integrated track/hold, and faster conversion (5 µs), making it optimal for high-fidelity, low-component-count industrial data acquisition where Cerdip reliability is valued.

Availability

AD7575BQ is available at Aetrix Electronics and suitable for industrial data acquisition, embedded motor control, portable test equipment, and ultrasonic NDT systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7575BQ 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design and manufacturing expertise spanning precision converters, amplifiers, and RF solutions.

The AD7575 family was developed to deliver cost-effective, easy-to-integrate 8-bit ADC functionality for microprocessor-based systems requiring fast, accurate digitization without external support components - especially in industrial and instrumentation applications.

FAQ

What is the operating temperature range for the AD7575BQ?

AD7575BQ is rated for industrial operation from –25°C to +85°C. This range is confirmed in the Ordering Guide section of the AD7575 datasheet Rev. B, where "B" denotes the industrial temperature grade and "Q" specifies the Cerdip package. The device maintains all specified electrical performance-including ±1/2 LSB total unadjusted error and 5 µs conversion time-across this full range.

Does the AD7575BQ require an external track-and-hold circuit?

No, the AD7575BQ does not require an external track-and-hold circuit. It integrates a complete track-and-hold function on-chip, as stated in the General Description and Product Highlights. This allows full-accuracy digitization of signals with slew rates up to 386 mV/µs (e.g., 2.46 V_PP at 50 kHz) without any external capacitor or amplifier components.

What reference voltage is required for the AD7575BQ to achieve specified performance?

The AD7575BQ requires a +1.23 V reference voltage applied to the VREF pin to achieve its specified performance, including ±1/2 LSB total unadjusted error and 5 µs conversion time. The datasheet specifies VREF = +1.23 V ±5%, and recommends using a low-impedance source such as the AD589 configured per Figure 10 to drive the code-dependent VREF input impedance (6–18 kΩ).

Can the AD7575BQ interface directly with a Z80H microprocessor?

Yes, the AD7575BQ can interface directly with a Z80H microprocessor. The datasheet explicitly lists Z80H among supported processors and provides a dedicated ROM Interface connection diagram (Figure 7). Using CS and RD control lines, the AD7575BQ operates in ROM mode-where the first READ starts conversion and the second READ retrieves valid data-without requiring WAIT state generation.

What is the purpose of the TP pin on the AD7575BQ?

TP (Test Pin) on the AD7575BQ is reserved for factory testing and must be hard-wired HIGH in all application circuits. The datasheet warns that TP should not be used as a feedthrough pin on double-sided PCBs and emphasizes that correct operation depends on TP being externally tied to VDD. It has no functional role during normal operation and leaving it floating may cause undefined behavior.