MAX7370_12 Datasheet, PDF (1/37 Pages) Maxim Integrated Products – 8 x 8 Key-Switch Controller and LED Driver/GPIOs

19-5950; Rev 1; 3/12
EVALUATION KIT AVAILABLE
MAX7370
8 x 8 Key-Switch Controller and LED Driver/GPIOs
with I²C Interface and High Level of ESD Protection
General Description
Features
The MAX7370 I²C-interfaced peripheral provides micro-
processors 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 5kI. 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 auto-
repeat, if enabled). An interrupt (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 x 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.
Applications
Cell Phones
Notebooks
PDAs
Handheld Games
Portable Consumer Electronics
For related parts and recommended products to use with this part,
refer to www.maxim-ic.com/MAX7370.related.
S Monitors Up to 64 Keys
S Integrated High-ESD Protection
±8kV IEC 61000-4-2 Contact Discharge
±15kV IEC 61000-4-2 Air-Gap Discharge
S Keyscan Uses Static Matrix Monitoring for
Low-EMI Operation
S Four LED Driver Pins on COL7–COL4
S 5V Tolerant, Open-Drain I/O Ports Capable of
Constant-Current LED Drive
S 256-Step PWM Individual LED Intensity-Control
Accuracy
S Individual LED Blink Rates and Common LED
Fade In/Out Rates from 256ms to 4096ms
S FIFO Queues Up to 16 Debounced Key Events
S User-Configurable Keypress and Release
Debounce Time (2ms to 32ms)
S Key-Switch Interrupt (INT) on Each Debounced
Event/FIFO Level, or End-of-Definable Time Period
S 1.62V to 3.6V Operating Supply Voltage
S Individually Programmable GPIOs to Two Logic
Levels
S 8-Channel Individual Programmable Level
Translators
S Provides Optional GPIOs on all ROW_ and COL_
Pins
S Supports Hot Insertion
S 400kbps, 5.5V Tolerant I²C Serial Interface with
Selectable Bus Timeout
Ordering Information appears at end of data sheet.
Typical Operating Circuit
+1.8V
+2.6V
+5V
VCC
VLA
MAX7370 _COL4
INT
MCU
SDA
SCL
COL5
COL6
I/O
COL7
I/O
AD0
ROW[0:7] ⁸
COL[0:3] ⁴
GND
32 KEYS
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or visit Maxim’s website at www.maxim-ic.com.