MAX7370 Maxim, MAX7370 Datasheet - Page 8

• Manufacturer Part Number: MAX7370
• Description: The MAX7370 I²C-interfaced peripheral provides microprocessors with management of up to 64 key switches, with optional GPIO and PWM-controlled LED drivers
• Manufacturer: Maxim

with I
The MAX7370 is a microprocessor peripheral low-noise
key-switch controller that monitors up to 64 key switches
with optional autorepeat, and key events that are pre-
sented in a 16-byte FIFO. Key-switch functionality can
be traded to provide up to 16 logic inputs. The device
also features 12 push-pull GPOs configured for digital
I/O and four open-drain GPOs configurable as constant-
current outputs for LED applications up to 5V. The device
supports a second 1.62V to 3.6V power supply for level
translation. The second logic supply voltage (V
be set equal to or higher than V
The device features an automatic sleep mode and auto-
matic wakeup that further reduce supply current con-
sumption. The device can be configured to enter sleep
mode after a programmable time following a key event.
The FIFO content is maintained and can be read in sleep
mode. The device does not enter autosleep when a key
is held down. The autowake feature takes the device
out of sleep mode following a keypress. Autosleep and
Table 1. Register Address Map and Power-Up Conditions
CODE (hex)
ADDRESS
8 x 8 Key-Switch Controller and LED Driver/GPIOs
0x00
0x01
0x02
0x03
0x05
0x06
0x30
0x31
0x34
0x35
0x36
0x37
2
C Interface and High Level of ESD Protection
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READ/WRITE
Read only
Detailed Description
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
CC
.
VALUE (hex)
POWER-UP
0x3F
0x0B
0xFF
0x00
0x00
0x07
0xFF
0x00
0x00
0x00
0xFF
0x0F
LA
) must
Key-switch size
Configuration
FUNCTION
GPO output
GPO output
REGISTER
Key repeat
Keys FIFO
Debounce
LED driver
direction 1
direction 2
Interrupt
mode 1
mode 2
enable
Sleep
GPIO
GPIO
autowake are enabled/disabled by programming the
configuration register (0x01).
To prevent overloading the microprocessor with too
many interrupts, interrupt requests can be triggered
after a programmable number of FIFO entries have been
exceeded, and/or after a set period of time (0x05). The
key-switch status is checked by reading the key-switch
FIFO. A 1-byte read access returns both the next key
event in the FIFO (if there is one) and the FIFO status.
Up to four of the key-switch outputs function as open-
drain GPOs capable of driving additional LEDs when the
application requires fewer keys to be scanned. For each
key-switch output used as a GPO, the number of moni-
tored key switches reduces by eight.
The device meets ESD requirements for ±8kV contact dis-
charge and 14kV Air-Gap Discharge on all key-switch pins.
On power-up, all control registers are set to power-up
values
(Table
Read FIFO keyscan data out
Power-down, key-release enable, autowake, and I
timeout enable
Key debounce time setting
Key-switch interrupt and INT frequency setting
Delay and frequency for key repeat
Idle time to autosleep
Keyscan switch array size
LED driver enable register
GPIO input/output control register 1 for
ROW7–ROW0
GPIO input/output control register 2 for COL7–COL0
GPO open-drain/push-pull output setting for
ROW7–ROW0
GPO open-drain/push-pull output setting for
COL7–COL0
1) and the device is in sleep mode.
DESCRIPTION
MAX7370
Initial Power-Up
2
C