NXP Semiconductors PCA9502BS,151

Overview

PCA9502BS,151 from NXP Semiconductors is an 8-bit I/O expander supporting selectable I²C-bus or SPI host interface, operating at 2.5 V or 3.3 V, with industrial temperature range (−40 °C to +85 °C), software reset capability, and 16 hardware-selectable slave addresses. It serves as a programmable GPIO extension for microcontroller-limited systems in portable battery-powered devices.

For engineers reviewing the PCA9502BS,151 datasheet, PCA9502BS,151 pinout, PCA9502BS,151 application, or PCA9502BS,151 equivalent, key selection criteria include dual-interface flexibility (I²C Fast-mode up to 400 kbit/s or SPI Mode 0 up to 15 Mbit/s), HVQFN24 package footprint constraints, interrupt-driven GPIO change detection, and register-level control of I/O direction, state, and latching behavior.

Technical Context

The PCA9502BS,151 implements a dual-mode serial interface controlled by the dedicated I2C/SPI pin: logic HIGH selects I²C-bus (open-drain SDA, noise-filtered SCL, Fast-mode compliant), while logic LOW enables SPI (Mode 0, 3-state SO, Schmitt-trigger CS/A0 and SI/A1). Internal register mapping includes IODir (0x0A), IOState (0x0B), IOIntEna (0x0C), and IOControl (0x0E) with software reset (SReset bit) and input latching (IOLatch bit).

GPIO pins (GPIO0–GPIO7) are fully programmable as inputs or outputs via IODir; interrupt generation on input state change is configurable per-pin in IOIntEna and supports both edge-triggered (non-latched) and level-captured (latched) modes. IRQ is open-drain, requires external pull-up (1 kΩ @ 3.3 V or 1.5 kΩ @ 2.5 V), and asserts active LOW upon enabled event.

Key Specifications

Pinout & Package

HVQFN24 package (SOT616-3): 4 mm × 4 mm × 0.85 mm body, thermal-enhanced, leadless, with exposed center pad requiring PCB ground connection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I/O expander applications.

Compared with PCA9502BS,151, the PCA9555D,118 offers double the I/O count but sacrifices interface flexibility and board-area efficiency, while the MCP23017-E/SP supports broader voltage operation yet lacks SPI, software reset, and latching-making PCA9502BS,151 optimal for compact, dual-protocol, interrupt-sensitive embedded expansions.

Availability

PCA9502BS,151 is available at Aetrix Electronics and suitable for factory automation, portable medical devices, and cellular data modems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for PCA9502BS,151 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

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with over 50 years of analog and mixed-signal design heritage.

The PCA9502 product line targets resource-constrained embedded systems needing flexible, low-power I/O expansion-designed specifically for hand-held, battery-operated, and industrial control applications where board space and interface adaptability are critical.

FAQ

What interface protocols does the PCA9502BS,151 support?

The PCA9502BS,151 supports two mutually exclusive serial interfaces selected by the I2C/SPI pin: I²C-bus (Fast-mode, up to 400 kbit/s) or SPI (Mode 0, up to 15 Mbit/s). It operates only as a slave in both modes. The interface selection is hardware-configured at power-up and cannot be changed dynamically during operation without resetting the device. This dual-mode capability allows the same PCA9502BS,151 to integrate into either I²C- or SPI-based host systems without redesign.

How many GPIO pins does the PCA9502BS,151 provide, and how are they configured?

The PCA9502BS,151 provides eight bidirectional GPIO pins (GPIO0 through GPIO7), each independently configurable as input or output via the IODir register (address 0x0A). Writing '1' to a bit sets the corresponding pin as output; writing '0' configures it as input. Input pins support interrupt-on-change (enabled per-pin in IOIntEna register), and output pins reflect values written to the IOState register (0x0B). All GPIOs tolerate 5.5 V when VDD is present, enabling safe level-shifting in mixed-voltage systems.

Does the PCA9502BS,151 support software reset, and how is it triggered?

Yes, the PCA9502BS,151 supports software reset via the SReset bit (bit 3) in the IOControl register (0x0E). Writing '1' to this bit initiates an immediate internal reset that clears all configuration registers (IODir, IOIntEna, IOControl) to their default states and sets all GPIOs to high-impedance inputs. The SReset bit automatically clears to '0' after reset completion. This feature enables full functional recovery without toggling the hardware RESET pin or cycling VDD-essential for unattended embedded systems.

What is the purpose of the IRQ pin on the PCA9502BS,151, and how is it used?

The IRQ pin on the PCA9502BS,151 is an open-drain, active LOW interrupt output that signals changes on enabled GPIO input pins. It asserts when any GPIO configured as input (via IODir) and enabled for interrupts (via IOIntEna) transitions state. An external pull-up resistor (1 kΩ for 3.3 V, 1.5 kΩ for 2.5 V) is required. Reading the IOState register clears the interrupt condition unless IOLatch is enabled. This enables efficient event-driven host polling instead of continuous GPIO scanning.

What package type and thermal considerations apply to the PCA9502BS,151?

The PCA9502BS,151 uses the HVQFN24 package (SOT616-3): 4 mm × 4 mm × 0.85 mm body with an exposed metal center pad. This pad must be soldered to a PCB ground plane for effective thermal dissipation and EMI suppression. With typical supply current of 750 µA and maximum power dissipation of 300 mW, the thermal design ensures reliable operation in ambient temperatures from −40 °C to +85 °C-critical for handheld and industrial deployments where airflow is limited.