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Microchip Technology MCP23S08T-E/SS
- Part No.:
- MCP23S08T-E/SS
- Manufacturer:
- Microchip Technology
- Category:
- I/O Expanders
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
MCP23S08T-E/SS.pdf
- Description:
- IC XPNDR 10MHZ SPI 20SSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
MCP23S08T-E/SS from Microchip Technology is an 8-bit SPI-based I/O expander IC designed to extend parallel GPIO capability in microcontroller-constrained systems. It features 8 bidirectional I/O pins (GP0–GP7), configurable interrupt output (INT), hardware address pins A1/A0 for up to four devices per chip select, and operates from 1.8V to 5.5V across –40°C to +85°C. Used in industrial HMI panels for button matrix scanning and LED status indication.
For engineers reviewing the MCP23S08T-E/SS datasheet, MCP23S08T-E/SS pinout, MCP23S08T-E/SS application, or MCP23S08T-E/SS equivalent, key selection considerations include its 10 MHz SPI interface speed, interrupt-on-change capability with DEFVAL/INTCON register control, internal 100 kΩ pull-up resistors, and SSOP-20 package compatibility with space-constrained PCB layouts.
Technical Context
The MCP23S08T-E/SS implements a register-mapped SPI slave interface with eleven 8-bit configuration registers (IODIR, IPOL, GPINTEN, DEFVAL, INTCON, IOCON, GPPU, INTF, INTCAP, GPIO, OLAT) accessible via 8-bit opcode + 8-bit address addressing. Its interrupt logic supports two mutually exclusive modes: pin-change detection or comparison against programmable DEFVAL register values.
Hardware address decoding uses A1 and A0 pins (biased externally), enabling up to four devices on a shared CS line. The IOCON register configures critical behaviors including sequential vs. byte-mode register access, INT pin polarity (INTPOL), open-drain mode (ODR), and hardware address enable (HAEN) - all essential for deterministic system-level timing and interrupt handling in real-time embedded applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| SPI Clock Speed | Up to 10 MHz - enables fast I/O state updates without CPU polling overhead in high-throughput sensor or display interfaces. |
| I/O Count | 8 bidirectional GPIO pins (GP0–GP7) - provides scalable digital I/O expansion without requiring additional MCU pins or complex multiplexing. |
| Supply Voltage Range | 1.8V to 5.5V at –40°C to +85°C - supports direct interfacing with both low-voltage logic (1.8V/3.3V) and legacy 5V systems. |
| Standby Current | 1 µA max - ensures minimal power draw in battery-backed or always-on industrial control nodes during idle states. |
| Interrupt Output | Configurable active-high/active-low/open-drain INT pin - allows flexible integration with MCU interrupt controllers or level-sensitive logic circuits. |
| Internal Pull-ups | 100 kΩ weak pull-up resistors per input pin (GPPU register controlled) - eliminates need for external biasing components in switch or encoder input designs. |
| Hardware Address Pins | A1 and A0 - enables up to four independent MCP23S08T-E/SS devices on one SPI bus using shared CS, reducing signal routing complexity. |
Pinout & Package
Package: 20-pin SSOP (0.209" width, 0.65 mm pitch), RoHS-compliant, surface-mount.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GP0–GP7 | Bidirectional I/O port | Configurable as input (with optional 100 kΩ pull-up) or output; supports interrupt-on-change and polarity inversion. |
| SCK | SPI clock input | Accepts master-generated clock up to 10 MHz; Schmitt-triggered for noise immunity on noisy industrial PCBs. |
| SI | SPI data input | Receives command opcodes, register addresses, and write data; TTL-compatible input buffer. |
| SO | SPI data output | Drives read data and status bits; push-pull output with 25 mA sink/source capability. |
| CS | Chip select input | Active-low enable; must be held low for entire SPI transaction; supports daisy-chain or multi-device configurations. |
| INT | Interrupt output | Open-drain or push-pull configurable; asserts when enabled GPIO pins change state or differ from DEFVAL. |
| RESET | External reset input | Asynchronous active-low reset; must be externally biased; initiates Power-on Reset sequence and register initialization. |
| A0, A1 | Hardware address inputs | Determine device address on SPI bus; must be externally tied to VDD or VSS; enable up to four devices per CS line. |
| VDD, VSS | Power supply terminals | Support 1.8V–5.5V operation; decoupling capacitor required near VDD pin for stable SPI timing at 10 MHz. |
| N/C | No-connect pins | Pins 10 and 11 in SSOP package - left unconnected; no internal connection or function. |
Key Features
| Feature | Design Value |
|---|---|
| Register-mapped SPI interface | 11 dedicated 8-bit registers (GPIO, IODIR, INTCON, etc.) enable precise control of I/O direction, interrupt behavior, and input polarity without firmware bit-banging. |
| Interrupt capture register (INTCAP) | Stores exact GPIO port state at interrupt trigger time - eliminates race conditions when reading port state after INT assertion. |
| Configurable interrupt source mode | Two mutually exclusive modes: pin-change detection or DEFVAL-register comparison - supports both edge-triggered and level-sensitive interrupt use cases. |
| Sequential/byte register access (IOCON.SEQOP) | Enables efficient burst reads/writes across consecutive registers or repeated access to single register (e.g., polling GPIO) without re-sending address bytes. |
| Internal weak pull-up resistors | 100 kΩ per pin, software-enabled via GPPU register - reduces BOM count and layout area for switch, encoder, or jumper input circuits. |
Applications
| Industrial HMI Keypad Interface | LED Status Panel Controller |
|---|---|
Use Scenario: Scanning 4×4 mechanical keypad matrix in factory-floor operator panel with limited MCU GPIO. IC Role / Device Role / Timing Role: MCP23S08T-E/SS acts as SPI-connected GPIO extender, scanning rows/columns and generating interrupt on keypress to wake MCU from low-power mode. Use Value: Reduces MCU GPIO usage by 8 pins; 10 MHz SPI enables sub-100 µs scan cycles; INT pin eliminates continuous polling. | Use Scenario: Driving 8 discrete status LEDs (power, fault, comms, etc.) on DIN-rail mounted PLC module. IC Role / Device Role / Timing Role: MCP23S08T-E/SS serves as output latch, receiving LED on/off commands over SPI from main controller and holding state independently. Use Value: Offloads GPIO management from host MCU; OLAT register ensures LED state persistence during SPI gaps; 25 mA drive supports direct LED connection without external drivers. |
| Modular Sensor Node Expansion | Legacy 5V System I/O Bridge |
Use Scenario: Adding digital input capability (limit switches, door sensors) to compact wireless sensor node powered by 3.3V LDO. IC Role / Device Role / Timing Role: MCP23S08T-E/SS provides isolated, interrupt-driven input monitoring; GPINTEN/INTCON registers configure edge-triggered detection per sensor. Use Value: 1.8V–5.5V operation matches 3.3V rail; 1 µA standby current preserves battery life; INTCAP register captures exact sensor state at interrupt time. | Use Scenario: Interfacing modern 3.3V microcontroller with legacy 5V industrial backplane signals (e.g., relay controls, indicator lamps). IC Role / Device Role / Timing Role: MCP23S08T-E/SS functions as level-tolerant I/O bridge, accepting 5V-tolerant inputs and driving 5V outputs while communicating via 3.3V SPI. Use Value: Absolute max rating of VDD+0.6V on I/O pins allows safe 5V signal handling; 25 mA output drive directly switches 5V relays or LEDs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I/O expander applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MCP23008T-E/SS | I²C interface (not SPI); three hardware address pins (A2–A0); max 1.7 MHz I²C clock vs. 10 MHz SPI. | Better suited for I²C-only systems with higher device density (up to 8 per bus); less suitable where SPI is mandated or higher throughput needed. | Select MCP23008T-E/SS only if I²C infrastructure exists and 10 MHz speed is unnecessary. |
| PCA9554APW,118 | I²C-only 8-bit expander (NXP); no interrupt capture register; fixed 100 kHz/400 kHz I²C speeds; no DEFVAL/INTCON flexibility. | Limited to basic interrupt-on-change without register-comparison mode; lacks INTCAP for state capture; lower design flexibility in complex event handling. | Choose PCA9554APW,118 for cost-sensitive, non-critical I²C applications where advanced interrupt features are unused. |
Compared with MCP23008T-E/SS and PCA9554APW,118, the MCP23S08T-E/SS delivers superior SPI throughput (10 MHz), flexible dual-mode interrupt logic, and hardware-address scalability for multi-device SPI buses - making it optimal for real-time industrial control where deterministic latency and configurability are critical.
Availability
MCP23S08T-E/SS is available at Aetrix Electronics and suitable for industrial HMI, modular sensor nodes, LED status panels, and legacy 5V system bridging requiring stable component supply and long-term production support.
Supply support for MCP23S08T-E/SS 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
Microchip Technology Inc. is a leading provider of microcontrollers, analog, FPGA, and connectivity solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.
The MCP23X08 product line delivers serial-interface GPIO expanders optimized for robust industrial and embedded applications, emphasizing interrupt flexibility, wide voltage operation, and seamless integration with resource-constrained host processors.
FAQ
What communication interface does the MCP23S08T-E/SS use?
The MCP23S08T-E/SS uses a 4-wire SPI interface (SCK, SI, SO, CS) supporting up to 10 MHz clock frequency. It does not support I²C - that functionality is provided by the pin-compatible but interface-different MCP23008 variant. The SPI protocol includes opcode-based addressing and supports both sequential and byte-mode register access via the IOCON register's SEQOP bit.
How many devices can share one chip select (CS) line with the MCP23S08T-E/SS?
Up to four MCP23S08T-E/SS devices can share a single chip select line, using the A1 and A0 hardware address pins to differentiate between devices. Each pin must be externally biased to VDD or VSS to set a unique 2-bit address (00, 01, 10, or 11). This enables scalable I/O expansion without adding extra CS signals or SPI buses.
Does the MCP23S08T-E/SS support interrupt-on-change with state capture?
Yes, the MCP23S08T-E/SS supports interrupt-on-change with full state capture via the INTCAP register. When an enabled GPIO pin triggers an interrupt (configured via GPINTEN and INTCON), the exact port value at the moment of interrupt is latched into INTCAP. This register is read-only and retains its value until cleared by reading either INTCAP or GPIO - ensuring reliable diagnostics in time-critical industrial applications.
What is the maximum output drive strength of the MCP23S08T-E/SS GPIO pins?
Each GPIO pin on the MCP23S08T-E/SS can source or sink up to 25 mA when configured as an output. This is sufficient to directly drive LEDs, small relays, or logic inputs without external buffers. The OLAT register maintains output state independently of SPI activity, and the 100 kΩ internal pull-up resistors (enabled via GPPU register) support clean input termination for switches and encoders.
Can the MCP23S08T-E/SS operate from a 1.8V supply?
Yes, the MCP23S08T-E/SS is fully specified to operate from 1.8V to 5.5V across the industrial temperature range (–40°C to +85°C). At 1.8V, it supports SPI communication up to 5 MHz (per datasheet DS20001919F, page 1), maintains 1 µA max standby current, and retains full register functionality - making it suitable for ultra-low-power and mixed-voltage embedded systems.
MCP23S08T-E/SS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Number of I/O:
- 8
- Interface:
- SPI
- Interrupt Output:
- Yes
- Features:
- POR
- Output Type:
- Push-Pull
- Current - Output Source/Sink:
- 25mA
- Clock Frequency:
- 10 MHz
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
MCP23S08T-E/SS FAQ
1.How can I place an order for MCP23S08T-E/SS through Aetrix?
Please submit a Request for Quotation (RFQ) for MCP23S08T-E/SS on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MCP23S08T-E/SS reliable?
The price and inventory of MCP23S08T-E/SS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MCP23S08T-E/SS is usually 5 days.
3.What payment methods are accepted for MCP23S08T-E/SS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MCP23S08T-E/SS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MCP23S08T-E/SS?
MCP23S08T-E/SS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MCP23S08T-E/SS order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MCP23S08T-E/SS?
For technical support, including MCP23S08T-E/SS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP23S08T-E/SS requirements.
6.How does Aetrix verify that MCP23S08T-E/SS is sourced from the original manufacturer or authorized distributors?
All MCP23S08T-E/SS products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MCP23S08T-E/SS meets industry standards.
7.What is the process for return or replacement of MCP23S08T-E/SS?
All MCP23S08T-E/SS units undergo pre-shipment inspection (PSI). If there is an issue with MCP23S08T-E/SS, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MCP23S08T-E/SS part is unused and in its original packaging.
Return procedure for MCP23S08T-E/SS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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