MCP23017T-E/SS - 16-Bit I2C I/O Expander | Microchip
MPN: MCP23017T-E/SS ✓ Active| Qty | Unit Price | Extended |
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| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
MCP23017T-E/SS Overview
An I/O expander is an interface IC that increases the number of digital input and output pins available to a host processor. The MCP23017 divides its 16 external lines into two 8-bit ports, GPA0-GPA7 and GPB0-GPB7, and transfers port data through a serial bus. This reduces the host's pin count while preserving individual control of switches, indicators, sensors, and other digital loads.
Key verified features include 16 I/O lines, I2C operation up to 1.7 MHz, seven address pins supporting device cascading and address extension, an interrupt output, and a reset function. The JLCPCB product listing reports approximately 1 µA quiescent current, 600 mV and 8 mA values, and a RoHS-compliant SSOP-28 device; the exact meaning and test conditions of the 600 mV and 8 mA entries must be confirmed in the manufacturer datasheet.
The MCP23017 is programmed through banked registers containing I/O direction, polarity, pull-up, interrupt-on-change, default, and port data functions. According to the manufacturer family documentation, the MCP23017 uses I2C while the MCP23S17 uses SPI. This distinction is important when replacing one family member with another because the serial protocols are not interchangeable.
Typical uses include industrial control panels, keypad scanning, relay or LED interface boards, sensor aggregation, and embedded systems requiring more GPIO than the host controller provides. The wide supply range supports both modern low-voltage systems and established 5 V designs, while the extended temperature range enables industrial equipment.
Designers should confirm the exact 28-pin pinout, open-drain interrupt behavior, address selection, and electrical limits against the manufacturer datasheet before layout release. PCB traces should keep I2C routing short, use appropriate pull-up resistors, and provide decoupling near the supply pins. Firmware must initialize every direction and configuration register explicitly because reset defaults do not necessarily match the intended board behavior.
This page consolidates verified manufacturer and distributor information, package details, application guidance, and replacement considerations beyond a basic catalog listing.
Drop-in alternatives for MCP23017T-E/SS — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MCP23017T-E/SS (same form factor and footprint) — differing in Interrupt Output, Package, Serial Interface.
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MCP23017T-E/SO
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MCP23017T-E/SS Specifications
| Number of I/O Lines | 16 |
| Serial Interface | I2C |
| Maximum I2C Clock Frequency | 1.7 MHz |
| Operating Supply Voltage | 1.8 V to 5.5 V |
| Operating Temperature | -40°C to +125°C |
| Number of I/O Ports | 2 |
| Bits per Port | 8 bits |
| Package | 28-SSOP |
| Package Width | 5.30 mm |
| Package Length | 0.209 inch |
| Mounting Type | Surface Mount |
| Quiescent Current | 1 µA |
| Reported Voltage Value | 600 mV |
| Reported Current Value | 8 mA |
| Address Extension | Supported |
| Device Cascading | Supported |
| Interrupt Output | Supported |
| Reset Function | Supported |
| RoHS Status | Compliant |
| Standard I2C Speeds Listed | 100 kHz, 400 kHz, and 1.7 MHz |
MCP23017T-E/SS 0.209 inch Pin Configuration Guide
Pin configuration for MCP23017T-E/SS (0.209 inch package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for MCP23017T-E/SS.
Refer to the datasheet for full pin configuration.
Typical Applications
MCP23017T-E/SS is suitable for 6 applications: Industrial Control Panels, Keypad and Human-Interface Input, LED and Relay Interface Boards, Sensor Aggregation Module, Battery-Powered Embedded System, Home Automation Controller.
Industrial Control Panels
The MCP23017T-E/SS is well suited to control-panel backplanes where a host controller needs more local inputs and outputs than its package can provide. Its two 8-bit ports create 16 external lines, while the 1.8 V to 5.5 V supply range supports common industrial logic levels. The interrupt output can connect change events from switches or sensors to the host, reducing unnecessary polling. Cascading and address extension help organize multiple control zones on one I2C bus. Verify pin-level drive limits and use suitable protection or driver stages for relays and off-board wiring.
Recommended
Keypad and Human-Interface Input
A matrix keypad can be monitored through a GPIO expander when the host has too few direct pins. The MCP23017T-E/SS provides 16 configurable lines, enabling row scanning and return inputs without consuming multiple dedicated host-controller ports. Its interrupt output can indicate line changes, although firmware must perform debouncing and manage the device's interrupt behavior correctly. Because GPB7 may have output-only restrictions in current documentation, treat pin direction claims as device-specific rather than assuming every line is fully bidirectional. Validate keypad timing and startup states in hardware.
Recommended
LED and Relay Interface Boards
The MCP23017T-E/SS can act as the serial-controlled gateway between a microcontroller and indicator or relay-driver circuitry. Its 16 lines provide flexible assignment across two ports, and its 1.7 MHz maximum I2C rate supports compact embedded control loops. The expander does not remove the need for correct external drivers: relay coils need transistor drive and flyback protection, while LED current must be limited. Confirm the exact output-current and voltage limits in the manufacturer electrical table. Program safe output states before enabling loads to avoid startup transients.
Recommended
Sensor Aggregation Module
The MCP23017T-E/SS can collect digital status signals from multiple sensors, switches, or alarm inputs while preserving I2C bandwidth for analog and memory devices. Sixteen lines allow several sensor-enable, threshold, or fault inputs to share one host interface. The interrupt output can reduce polling when an externally detectable change occurs, but level or edge behavior must be handled in firmware. Its -40°C to +125°C rating supports a broad range of industrial environments. For noisy or long external wiring, add protection networks, isolation, or filtering instead of relying solely on the expander.
Recommended
Battery-Powered Embedded System
The MCP23017T-E/SS can expand a low-power controller's available I/O without requiring a larger host package. Its verified 1.8 V minimum supply and reported 1 µA quiescent-current value make low-voltage operation a relevant starting point. Designers should still calculate the complete standby budget, including pull-ups, pull-up resistors, external drivers, and any regulated supply's own quiescent current. Avoid continuously enabled loads and configure unused pins deliberately. Verify whether every reported current is applicable to the exact voltage, temperature, and operating state required by the product.
Recommended
Home Automation Controller
The MCP23017T-E/SS is suitable for compact home-automation nodes that need to monitor doors, buttons, and indicators while driving local alarm or lighting-control signals. Sixteen I/O lines offer more flexibility than many small microcontrollers, and address extension allows additional modules to share the I2C bus. The interrupt output can wake or alert the host when a monitored input changes, though the host's low-power strategy must account for bus and pull-up current. Use external transistor stages for relays and mains-adjacent interfaces. Maintain strict galvanic separation wherever isolated mains circuitry is involved.
Recommended
Recommended Products Summary
Engineering reference data for MCP23017T-E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MCP23017T-E/SO | MCP23017T-E/SS |
|---|---|---|---|
| Package | 28-SSOP | SSOP-28 | SSOP-28 baseline |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| I/O Lines | 16 | 16 | 16 |
| Serial Interface | I2C | I2C | I2C |
Key Differentiators
- Exact-ordering clarity with a verified 28-SSOP package identity (vs MCP23017-E/SS)
- 16 external lines in two 8-bit ports (vs MCP23017-E/ML)
- Fast I2C capability (vs MCP23017T-E/SO)
Design Notes
Confirm the exact 28-SSOP footprint and every terminal assignment in the Microchip manufacturer datasheet before routing. The verified distributor data identifies a 28-SSOP, while one third-party page incorrectly lists a 28-VQFN exposed-pad package. Place the I2C pull-ups near the bus master or according to the system-level capacitance calculation, and keep SDA and SCL traces short, continuous, and away from switching nodes.
Do not assume all 16 pins can be used identically for input and output. The current family documentation associated with the MCP23017T-E/SO states that GPA7 and GPB7 are output-only. Check the exact device pin table and register map, configure direction bits explicitly after reset, and validate startup states in hardware. Incorrect assumptions here can cause contention, unexpected high outputs, or firmware that fails when a pin is loaded externally.
The verified listing reports 1 µA quiescent current, but the complete power budget must include I2C pull-up current, external logic, level shifters, and load drivers. For a continuously high bus, estimated pull-up current is VDD divided by the total effective pull-up resistance; this calculation must be confirmed against the actual bus voltage and resistor network. Decouple the supply locally and avoid switching-node routing under the MCP23017T-E/SS footprint.
The listed 1.7 MHz maximum is a device capability, not a guarantee for every PCB or voltage. Evaluate bus capacitance, pull-up strength, clock rise/fall time, voltage margin, and the number of connected devices. If ringing or overshoot appears, reduce the pull-up resistance within the driver's current limit or use a lower supported bus rate. Confirm the interrupt wiring and external protection so transient events do not violate the device's absolute maximum limits.
Compliance Information
RoHS compliance is reported on the verified JLCPCB product listing. Other environmental and automotive declarations were not verified for the exact ordering code.
