SX1508IULTRT - 8-bit I2C GPIO Expander with LED Driver | Semtech
MPN: SX1508IULTRT ✓ AktifSX1508IULTRT Ringkasan
An I/O expander is a type of interface IC that increases the number of general-purpose input/output pins available to a host microcontroller over a serial bus such as I2C. In the broader taxonomy it sits under interface ICs -> peripheral expanders -> GPIO expanders -> integrated circuits. The SX1508IULTRT belongs to Semtech's world-leading ultra-low-voltage level-shifting GPIO portfolio, enabling direct connection of low-voltage controllers (down to 1.2 V) to higher-voltage peripherals (up to 5.5 V tolerant) without external translator ICs.
Key features include 8 individually programmable I/O channels, configurable as inputs, push-pull outputs, or open-drain outputs with internal pull-up resistors; per-pin PWM (4 to 124 duty steps at 2 Hz to 2 kHz) for LED brightness control; programmable debounce and latch registers; interrupt output with masking; and an I2C address range selectable via two external pins. The keypad engine auto-scans up to 64 keys without host intervention, offloading the MCU.
Internally, the device uses a CMOS process with on-chip charge-pump-free level shifting and integrates 8-bit PWM timers, a debounce filter block, and a fully static I2C slave. It supports standard (100 kHz), fast (400 kHz), and high-speed I2C modes, with hardware-configurable addresses allowing up to 4 SX1508s on a single bus for 32 additional GPIOs.
Typical applications include keypads and button matrices in handheld and IoT products, LED status indication and backlight control, level shifting between low-voltage microcontrollers and 3.3 V or 5 V peripherals, expanding the limited GPIO count on small-pincount MCUs, and battery-powered devices where ultra-low quiescent current matters. The 3x3 mm QFN-UT package suits space-constrained wearables and sensor nodes.
When designing with this part, observe the 1.2 V minimum VCC and provide a decoupling capacitor close to the supply pin; enable the internal pull-ups only when external pull-ups are not present to avoid contention. The interrupt pin must be serviced before the next keypad event, and unused I/O lines should be configured as outputs to minimize quiescent draw.
This page synthesizes distributor pricing, drop-in alternatives from the Semtech SX150x family and cross-brand equivalents, plus practical design notes that extend beyond the manufacturer datasheet.
Alternatif penggantian untuk SX1508IULTRT — paket yang sama, pin-pada-pin kompatibel. Bagian paket yang berbeda memerlukan kerja ulang PCB diabaikan.
Variasi di dalam seri ini
Model-series yang sama yang kompatibel dengan penggantian SX1508IULTRT (sama faktor bentuk dan footprint) — berbeda di dalam I2C Clock Frequency, Interrupt Output, Package.
SX1509IULTRT
✅ Drop-In📋 Alternatif referensi (tidak dalam katalog)
SX1507IULTRT
✅ Drop-In📋 Alternatif referensi (tidak dalam katalog)
SX1508EVK
✅ Drop-In📋 Alternatif referensi (tidak dalam katalog)
SX1508IULTRT Rating Maksimal & Karakteristik Listrik
| Tipe Antarmuka | I2C (Standard / Fast / High-Speed) |
| Number of I/O | 8 |
| I2C Clock Frequency | 400 kHz |
| Supply Voltage (VCC) | 1.2 V to 3.6 V |
| I/O Voltage Tolerance | Up to 5.5 V |
| Output Drive | 8 mA per pin (sink/source) |
| LED PWM Frequency | 2 Hz to 2 kHz |
| LED PWM Resolution | 4 to 124 duty steps |
| Keypad Engine | Up to 8x8 matrix, auto-scan |
| Interrupt Output | Active-low INT with masking |
| Programmable Pull-ups | Yes (internal, per pin) |
| Selectable I2C Addresses | 4 (via ADDR0/ADDR1 pins) |
| Suhu Kerja | -40 C to +85 C |
| Paket | 20-QFN-UT (3x3 mm) Exposed Pad |
| Packaging | Tape & Reel (TR) |
| Tipe Mounting | Surface Mount |
| Status RoHS | Compliant |
Konfigurasi Pin SX1508IULTRT
| Pin produk 1 | GND — Ground reference |
| Pin produk 2 | SCL — I2C clock input |
| Pin produk 3 | SDA — I2C data (bidirectional, open-drain) |
| Pin produk 4 | ADDR0 — I2C address select bit 0 |
| Pin produk 5 | ADDR1 — I2C address select bit 1 |
| Pin produk 6 | INT — Interrupt output (active low, open-drain) |
| Pin produk 7 | RESET — Active-low hardware reset (tie to VCC if unused) |
| Pin produk 8 | IO0 — Bidirectional GPIO 0 / LED driver 0 / Keypad row 0 |
| Pin produk 9 | IO1 — Bidirectional GPIO 1 / LED driver 1 / Keypad row 1 |
| Pin produk 10 | IO2 — Bidirectional GPIO 2 / LED driver 2 / Keypad row 2 |
| Pin produk 11 | IO3 — Bidirectional GPIO 3 / LED driver 3 / Keypad row 3 |
| Pin produk 12 | IO4 — Bidirectional GPIO 4 / LED driver 4 / Keypad col 0 |
| Pin produk 13 | IO5 — Bidirectional GPIO 5 / LED driver 5 / Keypad col 1 |
| Pin produk 14 | IO6 — Bidirectional GPIO 6 / LED driver 6 / Keypad col 2 |
| Pin produk 15 | IO7 — Bidirectional GPIO 7 / LED driver 7 / Keypad col 3 |
| Pin produk 16 | VCC — Positive supply input (1.2 V to 3.6 V) |
| Pin produk 17 | NC — Not connected (per datasheet) |
| Pin produk 18 | NC — Not connected (per datasheet) |
| Pin produk 19 | NC — Not connected (per datasheet) |
| Pin produk 20 | EP — Exposed thermal pad (connect to GND) |
Aplikasi Umum
SX1508IULTRT cocok untuk 7 aplikasis: Handheld Device Keypads, LED Status Indicators and Backlights, Level Shifting Between 1.2 V MCUs and 5 V Peripherals, IoT Sensor Hubs and Wearable Devices, Industrial Control Panel GPIO Expansion, Battery-Powered Medical Devices, Automotive Infotainment Button Panels.
Handheld Device Keypads
The SX1508IULTRT drives 8x8 key matrix scanning with on-chip debounce and ghost-key prevention, eliminating host MCU polling for up to 64 keys. Operating from 1.2 V to 3.6 V, it suits handheld terminals, remote controls, and security panels powered by coin cells or Li-ion batteries; the integrated keypad FIFO holds events until the MCU wakes, enabling deep-sleep current below 1 uA in the host.
Direkomendasikan
LED Status Indicators and Backlights
Eight independent PWM channels drive status LEDs and backlights from 2 Hz to 2 kHz with 4 to 124 duty steps, eliminating host CPU timer overhead. The SX1508IULTRT per-pin PWM supports smooth fade-in/fade-out effects with linear or logarithmic curves, and 8 mA sink/source drive enables direct LED connection with a single series resistor. This is ideal for appliance front panels, industrial HMIs, and IoT devices with multi-color indicators.
Direkomendasikan
Level Shifting Between 1.2 V MCUs and 5 V Peripherals
With 1.2 V VCC and 5.5 V tolerant I/O pins, the SX1508IULTRT bridges modern low-voltage microcontrollers to legacy 3.3 V or 5 V sensors, displays, and actuators without external translator ICs. Each of the 8 I/O lines is independently configurable as input, push-pull, or open-drain with optional pull-up, simplifying bidirectional level translation. This reduces BOM cost and PCB area in mixed-voltage designs.
Direkomendasikan
IoT Sensor Hubs and Wearable Devices
The 3x3 mm QFN-UT package and 1.2 V operation make the SX1508IULTRT suited for wearables, fitness bands, and IoT sensor hubs where PCB area is at a premium and battery life is critical. With I2C addressing for up to 4 devices per bus, designers can scale to 32 GPIOs while the host MCU sleeps. The exposed pad aids thermal dissipation in always-on edge devices.
Direkomendasikan
Industrial Control Panel GPIO Expansion
Industrial HMIs, PLCs, and control panels often need more GPIOs than the host MCU offers; the SX1508IULTRT provides 8 rugged I/O lines with industrial temperature grade (-40 C to +85 C) and I2C isolation-friendly packaging. The integrated keypad engine supports 4x4 or 8x4 membrane keypads common on factory-floor panels, and the I2C interface pairs with digital isolators like Si864x for high-voltage safety isolation.
Direkomendasikan
Battery-Powered Medical Devices
Patient monitors, portable diagnostic kits, and infusion pumps benefit from the SX1508IULTRT's 1.2 V VCC and integrated keypad/LED engine that lets the host MCU remain in deep sleep until an event occurs. The RoHS-compliant 3x3 mm QFN-UT package meets space-constrained medical PCB layouts, and the I2C bus accommodates multiple devices on a single isolated rail, simplifying medical-grade safety design.
Direkomendasikan
Automotive Infotainment Button Panels
The SX1508IULTRT can drive 8x8 button matrices for HVAC, infotainment, and steering-wheel controls in vehicles; its industrial temperature grade and I2C interface simplify integration with automotive MCUs over CAN-translated buses. Note that the SX1508 is not AEC-Q100 qualified - for safety-critical automotive applications, prefer AEC-Q100-qualified GPIO expanders from NXP or Texas Instruments in similar QFN packages.
Direkomendasikan
Ringkasan Produk Direkomendasikan
Data referensi engineering untuk SX1508IULTRT — pembandingan, panduan desain, dan informasi konformitas.
Panduan Pemilihan
Pembandingan dengan Alternatif
| Parameter Umum | Produk Ini | SX1509IULTRT | SX1507IULTRT |
|---|---|---|---|
| Package | 20-QFN-UT (3x3 mm) | 20-QFN-UT (3x3 mm) - same | 20-QFN-UT (3x3 mm) - same |
| Brand | Semtech | Semtech | Semtech |
| Number of I/O | 8 | 16 | 4 |
| Supply Voltage | 1.2 V to 3.6 V | 1.2 V to 3.6 V | 1.2 V to 3.6 V |
| I2C Clock | 400 kHz | 400 kHz | 400 kHz |
| LED PWM Engine | Yes (8 channels) | Yes (16 channels) | Yes (4 channels) |
| Keypad Engine | Yes (8x8) | Yes (8x8) | Yes (4x4) |
| Output Drive Current | 8 mA | 8 mA | 8 mA |
| I/O Voltage Tolerance | 5.5 V | 5.5 V | 5.5 V |
| Lifecycle Status | Active | Active | Active |
Diferensiator Kunci
- Lowest voltage level-shifting GPIO expander (vsNXP PCA9538PW)
- Integrated LED PWM driver and keypad engine (vsMicrochip MCP23008T-E/ML)
- Compact 3x3 mm QFN-UT footprint (vsSX1509IULTRT (4x4 mm package))
Catatan Desain
The SX1508IULTRT operates from 1.2 V to 3.6 V on VCC; place a 0.1 uF decoupling capacitor within 5 mm of the VCC pin and a bulk 1 uF to 10 uF capacitor nearby. The exposed pad must be soldered to a ground plane with at least 4 thermal vias to a secondary ground layer for stable operation. Power-on sequence is not critical since I/Os remain tri-stated until configuration.
Route SCL and SDA as a differential pair if possible, keeping them short (<50 mm) and away from switching nodes. Place 2.2 kohm to 10 kohm pull-ups on SCL and SDA to VCC; the exact value depends on bus capacitance and desired rise time. The INT pin should have its own pull-up resistor if not provided by the host MCU.
Do not float the RESET pin; tie it to VCC through a 100 kohm resistor if no host reset control is needed. Do not exceed 5.5 V on any IO pin even when VCC is below 3.6 V - the IO lines tolerate 5.5 V but exceeding it will permanently damage the device. When using internal pull-ups, disable them if external pull-ups are present to avoid contention.
For long I2C buses or systems with multiple SX1508 devices, add bus repeaters or reduce clock frequency below 100 kHz to mitigate ringing. The I2C slave on the SX1508 holds SDA low briefly during acknowledge cycles - allow sufficient clock-stretching margin in the host MCU driver.
Informasi Konformitas
RoHS compliant per Semtech product page. NOT AEC-Q100 qualified - for automotive applications choose AEC-Q100-qualified GPIO expanders from NXP or TI in similar QFN-20 footprint.
