PCF8591 8-Bit I2C ADC DAC Chips and Modules

PCF8591 8-bit I2C analog conversion: choose the exact chip or board

The PCF8591 combines a four-input 8-bit analog-to-digital converter (ADC) with one 8-bit digital-to-analog output (DAC), controlled over an I2C bus. Browse PCF8591P through-hole ICs, PCF8591T/PCF8591AT surface-mount IC options, populated sensor-learning boards and a connector-equipped breakout. This collection also contains mixed-component listings and other conversion devices. Read the selected variant rather than interpreting every word in a multi-part product title as the contents of one shipment.

What the PCF8591 actually does

An analog sensor supplies a voltage to one of the four analog input channels; the converter reports an 8-bit digital result to a suitable I2C controller. Separately, an 8-bit code sent over I2C sets the chip's analog-output function. These are distinct directions of conversion: ADC is analog input to digital reading, while DAC is digital setting to analog output. This component is neither a voltage regulator nor an audio DAC system, despite generic “voltage regulator” labels in some source listings. It is a modest-resolution acquisition and control part suitable for demonstrations, sensor interfaces and low-resolution analog tasks where its specifications are acceptable, not an automatic substitute for a high-resolution measurement ADC.

The product descriptions for the populated PCF8591 teaching modules identify four external analog inputs, one analog output, serial SCL/SDA connections and a board supply described as 3.3–5 V. They describe a light-dependent resistor, a thermistor and an adjustable voltage source switched onto inputs by jumpers on particular boards. Those onboard sensors and jumper positions belong to the particular teaching-board layout, not the loose IC or every breakout in this collection. A sensor channel does not automatically report calibrated lux or temperature: its output is a voltage code and depends on the sensor circuit, supply, reference and your calibration.

Compare actual physical formats before ordering

• PCF8591P DIP-16: the through-hole, 16-pin option is appropriate to a matching socket or PCB footprint, not to an SOP-16 land pattern. The standalone DIP listings show choices such as 1, 5, 10 and 20 pieces; another DIP offer selects 2 or 5 pieces. Other multi-model listings also provide PCF8591P DIP-16 as one choice among unrelated chips. Select that exact variant and quantity. A heading that mentions PCF8591P does not make an AT28C256 EEPROM, OPA/AD amplifier, MAX3222 serial interface or other selectable device into a PCF8591.
• PCF8591T / PCF8591AT SOP-16: surface-mount listings offer quantities including 1, 3, 5, 10, 20, 50 and 100 depending on the product. One listing calls PCF8591T/2 in its heading but offers quantity-only choices, so confirm the exact marked suffix when it is essential. A separate listing switches between PCF8591AT and PCF8591T variants. Do not infer identical package dimensions, electrical limits or manufacturer sourcing merely from similar suffixes. Some truncated variant labels display “SOP-1” or “DIP-1”; read the full product and verify the package marking instead of assuming that truncated text establishes a different package.
• Conventional PCF8591 development modules: a populated board exposes VCC, GND, SDA and SCL, plus analog input and output connections. One detailed board description states approximately 36 × 23 mm PCB, a 1.6 mm board thickness and jumper-selectable light, temperature and potentiometer input circuits. Another module offers 1, 5 or 10 pieces, and a separate board listing offers a wider version with a line versus a narrower version without a wire. Those are options on different products, not a single universal module package.
• Module plus cable: a listing has separate “PCF8591 Module” and “Modules and Lines” selections. Check which selection includes connecting leads. Another product title mentions a cable but has only a Default Title variant; confirm package contents there rather than assuming every PCF8591 board ships with leads.
• STEMMA QT / Qwiic connector board: one product describes a PCF8591 ADC/DAC breakout equipped with this style of I2C connector. A physical keyed connector does not by itself establish compatible supply voltage, pin assignment, cable inclusion or plug-and-play software support for every host. Verify the exact breakout layout and host electrical specifications.

Eight-bit resolution and the analog range

Eight-bit conversion yields 256 possible codes per channel, rather than the finer quantization of 12-, 16- or 24-bit alternatives. On an ideal full-scale range of 0 to 5 V, one code step is on the order of 5 V / 256, approximately 19.5 mV; at 3.3 V it is approximately 12.9 mV. These arithmetic examples are not guaranteed accuracy, noise, integral nonlinearity or a promise that a selected module's external input safely tolerates 5 V. The effective range and reference arrangement depend on the supply, reference pins and specific board wiring. Check the manufacturer's datasheet for the exact IC and the selected board's schematic before choosing an input range or expecting a particular output swing.

Low-resolution does not eliminate analog-design details. Source impedance, sensor divider values, track-and-hold settling, ground noise, reference stability and I2C transaction timing affect readings. If several channels are scanned, follow the device's channel-selection and conversion sequence, and account for its data-transfer behavior rather than treating every received byte as a newly converted sample. The overall attainable sampling throughput depends on bus traffic and conversion behavior; a bus clock frequency is not the same thing as per-channel samples per second. The single DAC output is a low-resolution analog control signal, not a characterized power driver for motors, LEDs, speakers or arbitrary loads. Use appropriate external signal conditioning or drivers when required by the application.

I2C addressing and integration checklist

1. Confirm the selected format: choose DIP-16 for through-hole assembly, SOP-16 for a compatible surface-mount footprint, or an already assembled module for prototyping. Look for the exact selected variant and count; headings covering many models are menus, not mixed kits.
2. Check electrical domains: the PCF8591 board descriptions discuss 3.3 V or 5 V modules, while chip descriptions mention a 2.5–6 V device supply range. The chip's allowable range is not a blanket supply guarantee for onboard sensors, connectors or host I/O. Check VDD/VREF and logic-high requirements against the actual controller, and avoid putting a 5 V pull-up onto a 3.3 V-only host. Do not apply input voltages outside the part or board's permitted range.
3. Plan the shared bus: SDA and SCL need appropriate pull-ups and a common reference where specified by the system design. The three hardware address pins A0, A1 and A2 can select up to eight device-address configurations on a compatible bus, subject to address conflicts and correct board wiring. This is a device-address count, not eight analog input channels per chip. Confirm whether a board fixes or exposes those pins before planning a multi-board installation.
4. Trace the analog channels: a teaching module's P4/P5/P6 jumpers select its thermistor, photoresistor or adjustable input circuits; their location and effects are board-specific. Check whether an external sensor shares a selected onboard channel. Match the input mode, reference and expected voltage to the actual sensor. Calibrate physical units rather than treating an 8-bit code as degrees or lux.
5. Inspect the analog output: check AOUT and any indicator LED or load on the chosen board. An LED that brightens with a DAC setting on one training module is not evidence that a bare IC comes with an indicator or provides a precision buffered, full-scale output under any load.
6. Verify package and suffix: use current device documentation and package drawings for the exact PCF8591P, T or AT designation. Neither the collection name nor a reseller's generic voltage, temperature or power field is a reliable substitute for pinout, maximum ratings, timing or procurement documentation.

Other ADCs and DACs in mixed selections

One large multi-option listing offers PCF8591 “8Bit” boards in standard and “Big PCB” forms, with 1, 2, 5 or 10 pieces selected separately. The same product offers ADS1115 and ADS1015 ADC modules or loose ICs, ADS1110, ADS1118, ADS1120, ADS1220, MCP3421, SGM58031, AD5593 and MCP4725 choices. Those are distinct parts. ADS1015 and ADS1115 have different ADC resolutions; MCP4725 is a DAC rather than the PCF8591's combined four-input ADC and single-output DAC. ADS1118/ADS1120/ADS1220 use their own interface and measurement architectures; do not apply PCF8591 pinouts, address behavior or code formats to them. The broad listing description mixes technical statements across models, so its 2.0–5.5 V, programmable-gain, sample-rate and resolution claims must not be copied wholesale to a selected PCF8591 variant. A generic “28Bit” phrase in the listing is not a proven PCF8591 specification.

Many other multi-part listings offer a PCF8591P, PCF8591T or PCF8591AT variant beside unrelated devices such as PCF8563 clocks, PCF8574 I/O expanders, serial transceivers, memory ICs, op amps, logic devices, MOSFETs, display drivers and power components. The PCF8563 is not an ADC, and PCF8574 is not a PCF8591 DAC. A listing with an explicit “2PCS” heading still requires selection of the chip variant, while some “5PCS” multi-model listings choose the model but not an additional quantity multiplier. If a default-title listing names multiple model numbers without a selectable model, verify the delivered part before ordering. Do not infer a mixed assortment from a list of alternatives.

Clearly separate unrelated audio and wireless products

This page also surfaces a ZigBee CC2530/CC2591 UART wireless module and finished audio devices that belong to other product categories. A Nobsound M510, P1PLUS, WONDOM BEA1 or an ES9038Q2M desktop decoder is not a PCF8591 sensor-conversion module; the audio products have their own digital front ends, DAC chips, amplifier stages, power and connectors. VE Megatron S selections include device and bundle/accessory choices, and FiiO K11 choices differ by color and EU/US configuration. Do not use their audio resolution, Bluetooth, USB, certification or headphone-power descriptions as PCF8591 specifications. These listings remain visible here, but the selected product page and variant govern what is supplied.

For accurate purchasing, start with the function (8-bit I2C acquisition plus analog output), then the physical form, voltage and bus conditions, and finally the selected model and piece count. Avoid treating “original,” inspection, origin or broad compatibility language in a source listing as a verified guarantee across this collection. No products are excluded by this guide; it describes the differences so the actual option can be selected deliberately.