8 x 8 Key-Switch Controller and LED Driver/GPIOs with I²C Interface and High Level of ESD Protection

8 x 8 Key-Switch Controller with High Level of Integrated ESD Protection

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The MAX7370 I²C-interfaced peripheral provides microprocessors with management of up to 64 key switches, with optional GPIO and PWM-controlled LED drivers.

The key-switch drivers interface with metallic or resistive switches with on-resistances up to 5kΩ. Key inputs are monitored statically, not dynamically, to ensure low-EMI operation. The IC features autosleep and autowake modes to further minimize the power consumption of the device. The autosleep feature puts the device in a low-power state (1µA typ) after a timeout period. The autowake feature configures the device to return to normal operating mode from sleep upon a keypress.

The key controller debounces and maintains a FIFO buffer of keypress and release events (including autorepeat, if enabled). An interrupt (active-low INT) output can be configured to alert keypresses, as they occur, or at the maximum rate.

The same index rows and columns in the device can be used as a direct logic-level translator.

If the device is not used for key-switch control, all keyboard pins can be used as GPIOs. Each GPIO can be programmed to one of the two externally applied logic voltage levels. Four column ports (COL7–COL4) can also be configured as LED drivers that feature constant-current and PWM intensity control. The maximum constant-current level for each open-drain LED port is 20mA. The intensity of the LED on each open-drain port can be individually adjusted through a 256-step PWM control.

The device is offered in a 24-pin (3.5mm × 3.5mm) TQFN package with an exposed pad, and small 25-bump (2.159mm x 2.159mm) wafer-level package (WLP) for cell phones, pocket PCs, and other portable consumer electronic applications.

The device operates over the -40°C to +85°C extended temperature range.
MAX7370: Functional Block Diagram MAX7370:Functional Block Diagram Enlarge+

Key Features

  • Monitors Up to 64 Keys
  • Integrated High-ESD Protection
    • ±8kV IEC 61000-4-2 Contact Discharge
    • ±15kV IEC 61000-4-2 Air-Gap Discharge
  • Keyscan Uses Static Matrix Monitoring for Low-EMI Operation
  • Four LED Driver Pins on COL7–COL4
  • 5V Tolerant, Open-Drain I/O Ports Capable of Constant-Current LED Drive
  • 256-Step PWM Individual LED Intensity-Control Accuracy
  • Individual LED Blink Rates and Common LED Fade In/Out Rates from 256ms to 4096ms
  • FIFO Queues Up to 16 Debounced Key Events
  • User-Configurable Keypress and Release Debounce Time (2ms to 32ms)
  • Key-Switch Interrupt (active-low INT) on Each Debounced Event/FIFO Level, or End-of-Definable Time Period
  • 1.62V to 3.6V Operating Supply Voltage
  • Individually Programmable GPIOs to Two Logic Levels
  • 8-Channel Individual Programmable Level Translators
  • Provides Optional GPIOs on all ROW_ and COL_ Pins
  • Supports Hot Insertion
  • 400kbps, 5.5V Tolerant I²C Serial Interface with Selectable Bus Timeout


  • Cell Phones
  • Handheld Games
  • Notebooks
  • PDAs
  • Portable Consumer Electronics

See parametric specs for Keyswitch Controllers (3)

Part NumberInterfaceKeysI2C I/F Volt.ISUPPLY
Interrupt OutputKey Scan I2C Slave IDsGPIOVSUPPLY
maxtyptypSee Notes
I2C 100kbit/400kbit
Serial 2-Wire 400kbit
641.6 to 3.6351.5Yes416 GPIO1.62 to 3.6
$1.27 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: MAX7370.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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