SK5221 - Ultra-Low Power Low Cost HID over I2C FlexMatrix™ Keyboard Encoder with 1 external PS/2, 1 PWM Backlight and 9 LEDs Control, Field-Upgradable Bootloader


The SK5221 is an ultra-low power (0.3uA) HID over I2C interface keyboard encoder with 1 PWM backlight and 9 LEDs control. It’s the best choice for customized keyboard design for battery powered tablet / laptop / docking station / Instrument.

The SK5221 scans and encodes an 8-row by 20-column matrix. The key press events are translated to keyboard report. The encoder gets matrix information from on-chip matrix tables.

4 LED pins and 4 column pins are shared pins to meet different applications’ needs.

The SK5221 provides one key-controlled and command-controlled PWM for backlight LED PWM brightness control.

The SK5221 provides an external PS/2 port that supports hot plug and hot swap of PS/2 devices such as touchpad, pointing stick, mouse including wheel mice, and keyboard. The host can send commands via SK5221 PS/2 command relay feature to the external PS/2 device to change default settings.


  • HID over I2C v1.0 interface with Bootloader for field upgrade
  • One external PS/2 interface to PS/2 device such as mouse, touchpad, pointing stick, keyboard
  • 9 LEDs (4 shared with column scan pins)
  • 1 PWM backlight brightness control
  • FN key support
  • 8 x 20 matrix keyboard scan
  • Advanced ghost key detection algorithm to maximize the key combination without additional diodes
  • User-Programmable keyboard matrix
  • Remap external PS/2 mouse X,Y movement to horizontal, vertical scrolling
  • 4 Matrix Tables for LFn, RFn cases, NumLock On/Off cases
  • Support macro keys to generate like “Ctrl+Alt+Del”, or “Coke Cola”, “000” sequential string outputs
  • PS/2 command relay support
  • HID over I2C interface supports commands: RESET GET_REPORT SET_REPORT SET_POWER
  • Built-in oscillator and digital circuit. No external crystal is needed
  • LQFP 48 pin package: 7x7mm 1.6 Max (LxWxH)
  • Low power consumption: 0.3uA (no key pressed)
  • Operation voltage range: 2.7 to 5.5V
  • Industrial temperature range: -40°C to +85°C
  • Custom versions available in small and large quantities

Typical Applications

  • Laptop/Netbook PC's Internal Keyboard
  • Tablet PC's Cover Keyboard
  • Tablet/Mobile Phone Docking Station Embedded Keyboard
  • Instrument Control Panels
  • PS/2 to I2C Protocol Converter
SK5221 Typical Application Diagram
Typical Application - Laptop Internal Keyboard with an Attached PS/2 Touchpad or Pointing Stick

Support Software

Click here to download these tools.
FlexMatrix™ Tester
The software is used to test all Sprintek USB and PS/2 keyboard products.
FlexMatrix Tester Screenshot