Analog Devices Inc. AD7575JPZ

Overview

AD7575JPZ from Analog Devices is an 8-bit successive approximation analog-to-digital converter (ADC) with integrated track-and-hold, single +5 V supply operation, 5 µs conversion time, ±1 LSB total unadjusted error (J-grade), and 0 V to +2.46 V input range (with 1.23 V reference). It interfaces directly to 8-bit microprocessors including Z80H, 8085A-2, and 6502B via CS/RD control logic and outputs latched, three-state digital data on DB0–DB7.

For engineers reviewing the AD7575JPZ datasheet, AD7575JPZ pinout, AD7575JPZ application, or AD7575JPZ equivalent, key selection considerations include its unipolar/bipolar configurability, internal/external clock flexibility, 50 kHz full-power bandwidth, 100 ns data access time, and compatibility with memory-mapped or ROM-style microprocessor interfaces without external hold capacitors.

Technical Context

The AD7575JPZ employs a successive approximation register (SAR) architecture with on-chip track-and-hold that samples the analog input on the third falling edge of CLK after CS and RD go low. Its LC2MOS process enables single-supply operation and low power (15 mW typ), while the built-in clock oscillator (with RCLK/CCLK) or 4 MHz external clock supports deterministic timing.

Conversion accuracy is maintained by minimizing leakage on the internal hold capacitor-accuracy degrades above 5 µs conversion time due to charge loss-and the device uses a sampled-data comparator with 2 pF input capacitance and 500 Ω switch resistance, requiring low-impedance signal sources (<2 kΩ) for full-scale linearity.

Key Specifications

Pinout & Package

AD7575JPZ is packaged in a 20-terminal plastic leaded chip carrier (PLCC), designated P-20A per Analog Devices' ordering guide. Pin 1 identifier is marked on top surface; NC pins are not internally connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1112CPE+ and ADS7816U, the AD7575JPZ delivers faster parallel-data acquisition (5 µs, 100 ns access) and integrated track-and-hold in a legacy 5 V microprocessor environment-but requires more board area and offers only 8-bit resolution.

Availability

AD7575JPZ is available at Aetrix Electronics and suitable for industrial data acquisition, medical instrumentation, automated test equipment, and audio signal monitoring requiring stable component supply and long-term obsolescence management.

Supply support for AD7575JPZ 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.

The AD7575JPZ belongs to Analog Devices' legacy LC2MOS precision ADC product line, designed for cost-sensitive, 5 V microprocessor-based systems requiring fast, self-contained digitization without external support components.

FAQ

What is the maximum recommended source impedance for the AIN pin of the AD7575JPZ?

The AD7575JPZ analog input requires a low-impedance source to maintain full-scale linearity and minimize settling errors. Analog Devices specifies a maximum source resistance of 2 kΩ. Exceeding this value increases input settling time and may cause full-scale errors due to charging current through the 2 pF internal input capacitance. For optimal performance, keep AIN traces short and use a unity-gain buffer (e.g., TLC271) if driving from high-impedance sensors. This applies specifically to the AD7575JPZ in both unipolar and bipolar configurations.

Does the AD7575JPZ require external calibration for typical industrial applications?

No, the AD7575JPZ does not require external calibration in most industrial applications. Its J-grade specification guarantees ±1 LSB total unadjusted error over 0°C to +70°C, covering zero, full-scale, and linearity errors simultaneously. This level of inherent accuracy means offset and gain adjustments are unnecessary unless system-level requirements demand sub-LSB precision. The AD7575JPZ datasheet explicitly states that calibration is optional and provides procedures only for cases where tighter accuracy is needed-confirming that the AD7575JPZ operates within spec "out of the box" for standard use cases.

Can the AD7575JPZ operate with an internal clock, and what are the trade-offs?

Yes, the AD7575JPZ supports internal clock generation using an external resistor (RCLK = 100 kΩ) and capacitor (CCLK = 100 pF). This eliminates the need for an external clock source but introduces ±50% unit-to-unit variation in conversion time due to process tolerances. While nominal conversion is 5 µs at +25°C, it may range from ~2.5 µs to ~7.5 µs across temperature and lot. For timing-critical applications-especially those requiring consistent sampling intervals or software wait-state alignment-an external 4 MHz clock is recommended to guarantee 5 µs conversion and specified accuracy. This behavior is documented for the AD7575JPZ in Rev. B datasheet Figure 13 and Section "INTERNAL/EXTERNAL CLOCK".

What is the function of the TP pin on the AD7575JPZ, and how should it be connected?

TP (Test Pin) on the AD7575JPZ is a dedicated factory test node and must be hard-wired to a logic HIGH level (e.g., +5 V via 10 kΩ pull-up) in all operational circuits. It is not intended for user signal routing or as a feedthrough on double-sided PCBs. Leaving TP floating or pulling it low may activate internal test modes, causing undefined behavior or failure to convert. Analog Devices explicitly warns against using TP as an I/O pin-the AD7575JPZ will not function correctly unless TP is held HIGH. This requirement applies universally across all AD7575JPZ units regardless of temperature grade or package variant.

How does the AD7575JPZ handle bipolar input signals, and what external components are required?

The AD7575JPZ natively supports unipolar input (0–2.46 V) but can be configured for bipolar operation (±5 V) using an external op-amp circuit (Figure 17 in datasheet). This requires a precision inverting summing amplifier with matched 0.1% resistors (R2–R5), a rail-to-rail op-amp (e.g., TLC271), and proper decoupling. The AD7575JPZ itself outputs offset-binary codes; no internal configuration change is needed. Bipolar mode shifts the effective AIN range to 0–2.46 V while mapping ±5 V input to 0x00–0xFF output. LSB size becomes 39.06 mV, and calibration adjusts R3 (offset) and R4 (full-scale) per datasheet procedure. This capability is confirmed for the AD7575JPZ in the "BIPOLAR OPERATION" section of Rev. B.