MCP23S17T-E/SS - 16-Bit SPI I/O Expander, 10 MHz, SSOP-28
MPN: MCP23S17T-E/SS ✓ NakahandaMCP23S17T-E/SS Ulas
An I/O expander is a type of interface IC that sits between a host microcontroller and external peripherals or discrete signals, allowing a small MCU with limited native GPIO to control far more lines than its package allows. The MCP23S17 belongs to the I/O expander category (a sub-class of interface ICs), itself a sibling of the I2C-based MCP23017; both devices share identical pinout and register map, differing only in the serial protocol. This hierarchical placement — I/O expander -> interface IC -> peripheral IC -> semiconductor — lets the device act as a transparent extension of the host bus.
Key features include 16 individually configurable I/O lines, hardware configurable slave address via three external pins (up to eight devices on one SPI bus), 25 mA sink/source capability per pin, internal pull-up resistors (100 kΩ typical) user-enabled per pin, and a configurable interrupt output with open-drain behavior. The MCP23S17T-E/SS also provides sequential or simultaneous port update, polarity inversion register, and an input latch register for capturing transient events between SPI reads.
The architecture combines a CMOS SPI slave controller with two 8-bit bidirectional ports, each backed by latches for direction, polarity, pull-up, and interrupt control. The device operates from a single 1.8 V to 5.5 V supply, integrating level translation and ESD protection per pin (per JESD22-A114, HBM 2 kV typical per Microchip qualification). The wide supply tolerance lets it interface directly with both 3.3 V and 5 V MCUs without external level shifters.
Typical applications include adding keypad and matrix-scan inputs to consumer appliances, expanding relay and signal-lamp drive in industrial controllers, multiplexing LCD segment or LED driver lines in embedded displays, and providing auxiliary GPIO to small-form-factor MCUs such as the PIC16 or low-pin-count STM32 devices. The /SS (SPI slave-select) line allows up to eight MCP23S17 devices on a single SPI bus, yielding 128 I/O lines per controller.
When designing with this part, place 0.1 µF decoupling close to VDD/VSS, enable the internal pull-ups for input switches to suppress noise, and verify the SPI mode (CPOL/CPHA) and clock rate against the MCU. Reset is not required but tying RESET high via a 10 kΩ pull-up ensures clean startup.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, providing a single reference for engineers and procurement teams evaluating the MCP23S17T-E/SS.
Mga alternatibo na pwedeng ilagay na MCP23S17T-E/SS — parehas na package, pin-to-pin na katugmang. Hindi kasama ang mga bahagi ng iba't-ibang package na nangangailangan ng pagpapaayos ng PCB.
Variante sa Seri na ito
Katulad na modelo sa serye na katugma sa pagpasok MCP23S17T-E/SS (parehas na form factor at footprint) — pagkakaiba sa Interrupt Output, MSL Level, Package, Serial Interface, ESD Protection (HBM).
MCP23S17-E/SS
✅ Drop-InMagkontak para sa presyo
Tingnan ang Datasheet →MCP23S17T-E/SO
✅ Drop-In ⚠️ Mga Talaan Hindi Naiwerikmo📋 Alternatibo na Reference (hindi sa katalogo)
MCP23017T-E/SS
✅ Drop-In ⚠️ Mga Talaan Hindi NaiwerikmoMagkontak para sa presyo
Tingnan ang Datasheet →MCP23S17T-E/SSVAO
✅ Drop-In📋 Alternatibo na Reference (hindi sa katalogo)
MCP23S17T-E/SS Mga Spesipikasyon
| Product Type | 16-bit I/O Expander with SPI interface |
| Series | MCP23S17 |
| Number of I/O Pins | 16 (two 8-bit ports: GPA, GPB) |
| Serial Interface | SPI (Mode 0,0 and Mode 1,1) |
| Maksimum na Taktiko ng Oras | 10 MHz |
| Supply Voltage (VDD) | 1.8 V to 5.5 V |
| Maximum Supply Voltage | 5.5 V |
| Output Source/Sink Current per Pin | 25 mA |
| Internal Weak Pull-up Resistor | 100 kΩ typical (software-enabled per pin) |
| Interrupt Output | Yes (active-low, open-drain, configurable per pin) |
| Slave Address Selection | 3 external pins (A0, A1, A2) - up to 8 devices per SPI bus |
| Hanay ng Temperature na Operasyon | -40 °C to +125 °C |
| Packhaging | 28-pin SSOP (5.30 mm body) |
| Uri ng Pagpapasok | Surface Mount |
| Level ng MSL | 1 (per JEDEC J-STD-020) |
| Tindminan RoHS | Compliant |
| Lead-Free Finish | Yes (NiPdAu) |
| ESD Protection (HBM) | 2 kV per pin (per Microchip qualification) |
Pin Configuration ng MCP23S17T-E/SS
| Pin 1 | GPB0 — General purpose I/O port B bit 0 |
| Pin 2 | GPB1 — General purpose I/O port B bit 1 |
| Pin 3 | GPB2 — General purpose I/O port B bit 2 |
| Pin 4 | GPB3 — General purpose I/O port B bit 3 |
| Pin 5 | GPB4 — General purpose I/O port B bit 4 |
| Pin 6 | GPB5 — General purpose I/O port B bit 5 |
| Pin 7 | GPB6 — General purpose I/O port B bit 6 |
| Pin 8 | GPB7 — General purpose I/O port B bit 7 |
| Pin 9 | VDD — Positive supply voltage (1.8 V to 5.5 V) |
| Pin 10 | VSS — Ground reference |
| Pin 11 | NC — Not connected (per datasheet, pin reserved) |
| Pin 12 | SCK — SPI serial clock input |
| Pin 13 | SI — SPI serial data input (MOSI) |
| Pin 14 | SO — SPI serial data output (MISO) |
| Pin 15 | CS — SPI chip-select input (active low) |
| Pin 16 | RESET — Active-low hardware reset input |
| Pin 17 | A0 — Hardware address select bit 0 |
| Pin 18 | A1 — Hardware address select bit 1 |
| Pin 19 | A2 — Hardware address select bit 2 |
| Pin 20 | INTA — Port A interrupt output (active low, open-drain) |
| Pin 21 | INTB — Port B interrupt output (active low, open-drain) |
| Pin 22 | GPA0 — General purpose I/O port A bit 0 |
| Pin 23 | GPA1 — General purpose I/O port A bit 1 |
| Pin 24 | GPA2 — General purpose I/O port A bit 2 |
| Pin 25 | GPA3 — General purpose I/O port A bit 3 |
| Pin 26 | GPA4 — General purpose I/O port A bit 4 |
| Pin 27 | GPA5 — General purpose I/O port A bit 5 |
| Pin 28 | GPA6 — General purpose I/O port A bit 6 |
Tipikal na mga Gamit
MCP23S17T-E/SS ay nararapat para sa 6 aplikasyons: Keypad and Matrix-Scan Input Expansion, Industrial Relay and Solenoid Control, LCD and LED Display Multiplexing, Small-MCU Auxiliary GPIO Expansion, Automotive Body Electronics and Switch Reading, Portable and Battery-Powered Test Equipment.
Keypad and Matrix-Scan Input Expansion
The MCP23S17T-E/SS is a near-perfect fit for scanning 4x4 or 8x8 matrix keypads because its 16 lines split cleanly into two 8-bit ports (GPA and GPB) that can drive rows and read columns with hardware debounce. At 10 MHz SPI, scanning a 16-key matrix takes under 100 µs including the read sequence, well below any human-perceivable latency. The 100 kΩ internal pull-ups eliminate external resistors for the column lines, and the interrupt output pin wakes the host MCU only when a key is pressed, enabling low-power sleep modes. Compared to discrete diode-matrix scanning, this approach saves 8-12 GPIOs on the host and provides hardware-level interrupt support.
Inirekomenda
Industrial Relay and Solenoid Control
Industrial control panels often need to drive 16-32 relays or solenoids but the host PLC or MCU runs out of GPIO. The MCP23S17T-E/SS exposes 16 lines capable of sourcing or sinking 25 mA per pin, enough to directly drive low-power signal relays or opto-coupler inputs; for larger loads, use the MCP23S17 outputs as gate signals to MOSFETs or darlington drivers like the ULN2803. The wide 1.8 V to 5.5 V supply range lets the same expander operate from a 3.3 V MCU on a 24 V industrial bus via external level shifters. The interrupt output flags the PLC when a remote sensor asserts, allowing event-driven polling rather than continuous scans.
Inirekomenda
LCD and LED Display Multiplexing
Character LCDs (HD44780-based), segment LCDs, and discrete LED arrays often need 12-20 control lines, exhausting small microcontrollers. By using an MCP23S17T-E/SS as a remote GPIO extender, a small MCU only needs 3 SPI lines (SCK, MOSI, MISO, plus CS) to control up to 16 display lines, freeing native pins for other functions. The 10 MHz SPI clock updates a 16-bit display register in under 2 µs, fast enough for full-motion refresh of multiplexed LED matrices. The device's 5 V tolerance lets it drive 5 V LCD logic directly from a 3.3 V MCU without level translation.
Inirekomenda
Small-MCU Auxiliary GPIO Expansion
Modern low-pin-count MCUs (PIC16, ATtiny, low-pin STM32) often ship in 8- or 14-pin packages with 4-6 usable GPIO. The MCP23S17T-E/SS adds 16 lines via just 4 SPI pins (SCK, MOSI, MISO, CS), turning an 8-pin MCU into a system with effectively 22 I/O. This is especially valuable for IoT endpoints and sensor hubs that need many digital sensors or buttons but must use a tiny, low-power host. The interrupt output pins let the MCP23S17 wake a sleeping host from deep-sleep on sensor events, dramatically reducing system power consumption.
Inirekomenda
Automotive Body Electronics and Switch Reading
The automotive-qualified variant MCP23S17T-E/SSVAO is suitable for reading body-control signals - door switches, light sensors, mirror position encoders - over SPI from a BCM (Body Control Module). With 16 inputs tolerant to 5.5 V and protected by 2 kV HBM ESD, the device handles the harsh automotive environment including cranking transients when paired with external TVS protection. The interrupt output wakes the BCM when any monitored switch changes state, and the cascadable address pins allow up to 128 inputs per BCM SPI port. AEC-Q100 qualification is mandatory for automotive production.
Inirekomenda
Portable and Battery-Powered Test Equipment
Handheld test equipment often needs to scan many user inputs (buttons, rotary encoders, function keys) while running from a small Li-ion cell. The MCP23S17T-E/SS draws only a few µA in standby and its interrupt output allows the host MCU to sleep until a button is pressed, extending battery life significantly. The 1.8 V minimum supply lets it run directly from a discharged Li-ion cell (down to 3.0 V) without boost converters. Up to 8 cascaded devices on one SPI bus support 128-input test fixtures or scan heads.
Inirekomenda
Buod ng mga Inirekomendang Produkto
Impormasyon ng Talumpati sa Engineering for MCP23S17T-E/SS — ikabit, gabay sa disenyo, at impormasyon ng pagsunod sa kautusan.
Paunawang Hanapin
Ikabit sa Mga Alternatibo
| Parametro | Ito ang Producto | MCP23S17-E/SS | MCP23S17T-E/SSVAO | MCP23017T-E/SS |
|---|---|---|---|---|
| Package | SSOP-28 | SSOP-28 (same) | SSOP-28 (same) | SSOP-28 (same) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Serial Interface | SPI | SPI | SPI | I2C |
| Maximum Clock Frequency | 10 MHz | 10 MHz | 10 MHz | 400 kHz (I2C fast mode) / 1.7 MHz (high-speed) |
| Number of I/O Pins | 16 | 16 | 16 | 16 |
| Supply Voltage Range | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| Output Current per Pin | 25 mA source/sink | 25 mA source/sink | 25 mA source/sink | 25 mA source/sink |
| Hardware Address Pins | 3 (up to 8 devices/bus) | 3 (up to 8 devices/bus) | 3 (up to 8 devices/bus) | 3 (up to 8 devices/bus) |
| Operating Temperature | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C (AEC-Q100) | -40 °C to +125 °C |
| Automotive Qualification | No | No | Yes (AEC-Q100) | No |
Pangunahing mga Pagkakaiba
- SPI interface at 10 MHz - 25x faster than I2C-based MCP23017 (kumpara saMCP23017T-E/SS)
- Open-drain interrupt outputs INTA and INTB (one per port) (kumpara saMCP23S17T-E/SSVAO)
- Automotive-qualified VAO variant available in same footprint (kumpara saMCP23S17T-E/SSVAO)
- Hardware address pins support 8 devices per SPI bus (128 I/O total) (kumpara saMCP23S17-E/SS)
Talaan ng Disenyo
Decouple VDD with a 0.1 µF ceramic capacitor placed within 5 mm of the VDD pin (pin 9) and VSS pin (pin 10). Add a bulk 1 µF to 10 µF tantalum or ceramic capacitor near the device to suppress SPI-bus-induced switching transients. The MCP23S17T-E/SS draws a few hundred µA during active SPI transactions and only standby current (~1 µA typical) when the bus is idle, so a small bulk cap is sufficient.
Keep SPI traces short (<50 mm) and route SCK, SI, SO together as a matched bus. Place a 33 Ω series resistor near the SCK source pin if the bus exceeds 50 mm, to dampen ringing. The CS line should be pulled high via a 10 kΩ pull-up to VDD (in case the master MCU does not initialize CS as high-impedance during reset) to prevent unintended chip selection during MCU power-up. The INTA/INTB open-drain outputs require external 10 kΩ pull-ups to VDD.
Do not leave RESET floating - tie it to VDD via a 10 kΩ pull-up, or to a host GPIO for software-controlled reset. The three address pins (A0, A1, A2) must be tied to VDD or GND before power-up; floating address pins can latch the device into an undefined address state. The IOCON.BANK bit must be set or cleared consistently with the chosen register access scheme (sequential vs banked); mismatched configuration between write and read sequences causes register mapping errors. Finally, do not exceed 25 mA per pin or the absolute maximum total package current - external drivers are required for relays, solenoids, or LED strings.
Impormasyon ng Pagsunod sa Kautusan
RoHS compliant per Microchip product page. Not AEC-Q100 qualified - choose MCP23S17T-E/SSVAO for automotive. MSL 1 per JEDEC J-STD-020 means unlimited floor life at <30 °C / 85% RH.
