MAXIM MAX7359 User Manual
General Description
The MAX7359 I2C interfaced peripheral provides microprocessors with management of up to 64 key switches.
Key codes are generated for each press and release of
a key for easier implementation of multiple key entries.
Key inputs are monitored statically, not dynamically, to
ensure low-EMI operation. The switches can be metallic
or resistive (carbon) with up to 5kΩ of resistance.
The MAX7359 features autosleep and autowake to further minimize the power consumption of the device.
The autosleep feature puts the device in a low-power
state (1µA typ) after a sleep timeout period. The
autowake feature configures the MAX7359 to return to
normal operating mode from sleep upon a key press.
The key controller debounces and maintains a FIFO of
key-press and release events (including autorepeat, if
enabled). An interrupt (INT) output can be configured to
alert key presses either as they occur, or at maximum rate.
Any of the column drivers (COL2/PORT2–COL7/PORT7)
or the INT, if not used, can function as a general-purpose output (GPO).
The MAX7359 is offered in small, 24-pin TQFN (3.5mm x
3.5mm) and 25-bump WLP (2.31mm x 2.31mm) packages for cell phones, pocket PCs, and other portable
consumer electronic applications. The MAX7359 operates over the -40°C to +85°C temperature range.
Applications
Cell Phones
PDAs
Handheld Games
Portable Consumer Electronics
Features
o Optional Key Release Detection on All Keys
o Monitor Up to 64 Keys
o +1.62V to +3.6V Operation
o Autosleep and Autowake to Minimize Current
Consumption
o Under 1µA Sleep Current
o FIFO Queues Up to 16 Debounced Key Events
o Key Debounce Time User Configurable from 9ms
to 40ms
o Low-EMI Design Uses Static Matrix Monitoring
o Hardware Interrupt at the FIFO Level or at the End
of Definable Time Period
o Up to Seven Open-Drain Logic Outputs Available
Capable of Driving LEDs
o 400kbps, 5.5V-Tolerant, 2-Wire Serial Interface
o Selectable 2-Wire, Serial-Bus Timeout
o Four I2C Address Choices
o Small, 24-Pin TQFN Package (3.5mm x 3.5mm) , or
25-Pin WLP Package (2.31mm x 2.31mm)
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-0850; Rev 4; 6/10
EVALUATION KIT
AVAILABLE
+
Denotes a lead(Pb)-free/RoHS-compliant package.
*
EP = Exposed pad.
MAX7359
V
CC
COL_
GND
8
SCL
SDA
AD0
ROW_
8
SWITCH
ARRAY,
UP TO 64
SWITCHES
INPUT
+1.62V TO +3.6V
INT
Typical Application Circuits
Typical Application Circuits continued at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Pin Configurations
Pin Configurations continued at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX7359ETG+ -40°C to +85°C 24 TQFN-EP*
MAX7359EWA+ -40°C to +85°C 25 WLP
TOP VIEW
COL7/PORT7
ROW0
ROW1
*EP = EXPOSED PAD.
SCL
18 17 16 15 14 13
19
INT
20
V
CC
21
N.C.
22
23
24
+
123456
ROW2
(3.5mm x 3.5mm)
SDA
AD0
MAX7359
ROW3
COL3/PORT3
TQFN
GND
I.C.
EP*
ROW4
COL4/PORT4
COL0
ROW5
12
11
10
9
8
7
COL1
COL2/PORT2
COL5/PORT5
COL6/PORT6
ROW7
ROW6
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
(All voltages referenced to GND.)
V
CC
..........................................................................-0.3V to +4V
COL2/PORT2–COL7/PORT7 ....................................-0.3V to +4V
SDA, SCL, AD0, INT .................................................-0.3V to +6V
All Other Pins..............................................-0.3V to (V
CC
+ 0.3V)
DC Current on COL2/PORT2–COL7/PORT7 ......................25mA
GND Current .......................................................................80mA
Continuous Power Dissipation (T
A
= +70°C)
24-Pin TQFN (derate 15.4mW/°C above +70°C) ........1229mW
25-Bump WLP (derate 19.2mW/°C above +70°C)......1194mW
Junction-to-Case Thermal Resistance (
θ
J
C
) (Note 1)
24-Pin TQFN.................................................................5.4°C/W
25-Bump WLP ...............................................................17°C/W
Junction-to-Ambient Thermal Resistance (
θ
J
A
) (Note 1)
24-Pin TQFN...............................................................65.1°C/W
25-Bump WLP ...............................................................53°C/W
Operating Temperature Range (T
MIN
to T
MAX
) .....-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (TQFN only, soldering, 10s) ..............+300°C
Soldering Temperature (reflow) .......................................+260°C
ELECTRICAL CHARACTERISTICS
(VCC= +1.62V to +3.6V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VCC= +2.5V, TA= +25°C.) (Notes 2, 3)
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial
.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Supply Voltage V
Operating Supply Current I
Sleep-Mode Supply Current I
POR 1.0 1.6 V
POR Hysteresis PORHYST VCC rising 42 mV
Key-Switch Source Current I
Key-Switch Source Voltage V
Key-Switch Resistance R
Startup Time from Shutdown t
Output Low Voltage
COL2/PORT2 to COL7/PORT7
INT Output V
Oscillator Frequency F
SERIAL-INTERFACE SPECIFICATIONS
Serial Bus Timeout t
Input High Voltage
SDA, SCL, AD0
Input Low Voltage
SDA, SCL, AD0
Output Low Voltage SDA V
Input Leakage Current VCC = 0V to +6V -1 +1 µA
CC
All key switches open, oscillator running,
CC
SL
KEY
KEY
KEY
START
V
OLPORTISINK
OLINTISINK
OSC
OUT
V
V
OLPORTISINK
COL2–COL7 configured as key switches
N keys pressed
Operating mode 0.42 0.55 V
(Note 4) 5 kΩ
With bus timeout enabled 10 40 ms
IH
IL
= 10mA 0.2 V
= 10mA 0.5 V
= 10mA 0.4 V
1.62 3.60 V
0.7 x
V
CC
20 x N)
25 60
(25 +
0.6 5 µA
20 35 µA
2 2.4 ms
64 kHz
0.3 x
V
CC
µA
V
V
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
_______________________________________________________________________________________ 3
I2C TIMING CHARACTERISTICS
(VCC= +1.62V to +3.6V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VCC= +2.5V, TA= +25°C.) (Notes 2, 3)
Note 2: All parameters are tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 3: All digital inputs at V
CC
or GND.
Note 4: Guaranteed by design.
Note 5: C
b
= total capacitance of one bus line in pF. tRand tFmeasured between +0.3VCCand +0.7VCC.
Note 6: A master device must provide a hold time of at least 300ns for the SDA signal (referred to V
IL
of the SCL signal) to bridge
the undefined region of SCL’s falling edge.
Note 7: I
SINK
≤ 6mA.
Note 8: Input filters on the SDA, SCL, and AD0 inputs suppress noise spikes less than 50ns.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Capacitance
(SCL, SDA, AD0)
SCL Serial-Clock Frequency f
Bus Free Time Between a STOP
and a START Condition
Hold Time (Repeated) START
Condition
Repeated START Condition
Setup Time
STOP Condition Setup Time t
Data Hold Time t
Data Setup Time t
SCL Clock Low Period t
SCL Clock High Period t
Rise Time of Both SDA and SCL
Signals, Receiving
Fall Time of Both SDA and SCL
Signals, Receiving
Fall Time of SDA Transmitting t
Pulse Width of Spike Suppressed t
C ap aci ti ve Load for E ach Bus Li ne C
t
t
C
SCL
t
BUF
HD, STA
SU, STA
SU, STO
HD, DAT
SU, DAT
LOW
HIGH
t
t
F, TX
SP
(Notes 4, 5) 10 pF
IN
Bus timeout disabled 0 400 kHz
1.3 µs
0.6 µs
0.6 µs
0.6 µs
(Note 6) 0.9 µs
100 ns
1.3 µs
0.7 µs
(Notes 4, 5)
R
(Notes 4, 5)
F
(Notes 4, 7)
(Notes 4, 8) 50 ns
(Note 4) 400 pF
b
0.1C
0.1C
0.1C
20 +
20 +
20 +
b
b
b
300 ns
300 ns
250 ns
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VCC= +2.5V, TA= +25°C, unless otherwise noted.)
GPO PORT OUTPUT LOW VOLTAGE
vs. SINK CURRENT
300
VCC = +2.4V
250
200
(mV)
150
OL
V
100
50
0
010155202530
TA = +85°C
TA = +25°C
I
SINK
SUPPLY CURRENT vs. SUPPLY VOLTAGE
40
AUTOSLEEP = OFF
35
30
25
SUPPLY CURRENT (µA)
20
15
1.6 2.42.0 2.8 3.2 3.6
TA = +85°C
TA = +25°C
SUPPLY VOLTAGE (V)
(mA)
TA = -40°C
TA = -40°C
MAX7359 toc01
MAX7359 toc04
GPO PORT OUTPUT LOW VOLTAGE
vs. SINK CURRENT
300
VCC = +3.0V
250
200
(mV)
150
OL
V
100
50
0
010515202530
TA = +85°C
T
= +25°C
A
I
(mA)
SINK
TA = -40°C
KEY-SWITCH SOURCE CURRENT
vs. SUPPLY VOLTAGE
22.0
COL0 = GND
21.5
21.0
20.5
KEY-SWITCH SOURCE CURRENT (µA)
20.0
1.6 3.6
TA = +85°C
TA = -40°C
TA = +25°C
3.22.82.42.0
SUPPLY VOLTAGE (V)
MAX7359 toc02
MAX7359 toc05
GPO PORT OUTPUT LOW VOLTAGE
vs. SINK CURRENT
300
VCC = +3.6V
250
200
(mV)
150
OL
V
100
50
0
010515202530
TA = +85°C
TA = +25°C
I
(mA)
SINK
TA = -40°C
SLEEP MODE SUPPLY CURRENT
vs. SUPPLY VOLTAGE
2.0
1.5
1.0
0.5
SHUTDOWN SUPPLY CURRENT (µA)
0
1.6 2.62.1 3.1 3.6
SUPPLY VOLTAGE (V)
MAX7359 toc03
MAX7359 toc06
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
_______________________________________________________________________________________ 5
Functional Block Diagram
INT
SDA
SCL
MAX7359
INTERFACE
TIMEOUT
*GPO
I2C
BUS
64kHz
OSCILLATOR
CONTROL
REGISTERS
FIFO
POR
KEY SCAN
COLUMN ENABLE
GPO ENABLE
CURRENT DETECT
ROW ENABLE
COL0
COL1
CURRENT
SOURCE
COLUMN
DRIVES
OPENDRAIN
ROW
DRIVES
COL2*
COL3*
COL4*
COL5*
COL6*
COL7*
ROW0
ROW1
ROW2
ROW3
ROW4
ROW5
ROW6
ROW7
MAX7359
2-Wire Interfaced Low-EMI
Key Switch Controller/GPO
6 _______________________________________________________________________________________
Detailed Description
The MAX7359 is a microprocessor peripheral low-noise
key-switch controller that monitors up to 64 key switches
with optional autorepeat, and key events are presented
in a 16-byte FIFO. Key-switch functionality can be traded
to provide up to six open-drain logic outputs.
The MAX7359 features an automatic sleep mode and
automatic wakeup that further reduce supply current consumption. The MAX7359 can be configured to enter sleep
mode after a programmable time following a key event.
The FIFO content is maintained during sleep mode and
can be read in sleep mode. The MAX7359 does not enter
autosleep when a key is held down. The autowake feature
takes the MAX7359 out of sleep mode following a keypress event. Autosleep and autowake can be disabled.
Interrupt requests can be configured to be issued on a
programmable number of FIFO entries, or can be set
to a period of time to prevent overloading the microprocessor with too many interrupts. The key-switch status can be checked at any time 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, so it is easy to operate the MAX7359 by
polling. If the INT pin is not required, it can be configured as an open-drain general-purpose output (GPO)
capable of driving an LED.
If the application requires fewer keys to be scanned, up
to six of the key-switch outputs can be configured as
open-drain GPOs capable of driving LEDs. For each
key-switch output used as a GPO, the number of key
switches that can be scanned is reduced by eight.
Pin Description
PIN
TQFN WLP
1A1
2A2
3A3
4B3
5A4
6A5
7B5
8B4
9C5
10 C4
11 D5
12 E5
13 E4
14 D4
15 D3
16 E3
17 E2
18 D2
19 E1
20 D1
21 C2, C3
22 C1
23 B2
24 B1
——
NAME FUNCTION
ROW2 Row Input from Key Matrix. Leave ROW2 unconnected or connect to GND if unused.
ROW3 Row Input from Key Matrix. Leave ROW3 unconnected or connect to GND if unused.
COL3/PORT3 Column Output to Key Matrix or GPO. Leave COL3/PORT3 unconnected if unused.
COL4/PORT4 Column Output to Key Matrix or GPO. Leave COL4/PORT4 unconnected if unused.
ROW4 Row Input from Key Matrix. Leave ROW4 unconnected or connect to GND if unused.
ROW5 Row Input from Key Matrix. Leave ROW5 unconnected or connect to GND if unused.
ROW6 Row Input from Key Matrix. Leave ROW6 unconnected or connect to GND if unused.
ROW7 Row Input from Key Matrix. Leave ROW7 unconnected or connect to GND if unused.
COL6/PORT6 Column Output to Key Matrix or GPO. Leave COL6/PORT6 unconnected if unused.
COL5/PORT5 Column Output to Key Matrix or GPO. Leave COL5/PORT5 unconnected if unused.
COL2/PORT2 Column Output to Key Matrix or GPO. Leave COL2/PORT2 unconnected if unused.
COL1 Column Output to Key Matrix. Leave COL1 unconnected if unused.
COL0 Column Output to Key Matrix. Leave COL0 unconnected if unused.
I.C. Internally Connected. Connect to GND for normal operation.
GND Ground
AD0 Adddress Input. ADO selects up to four device slave addresses (Table 10).
SDA I
SCL I
INT Active-Low Interrupt Output. INT is open drain.
V
CC
N.C. No Connection. Not internally connected.
COL7/PORT7 Column Output to Key Matrix or GPO. Leave COL7/PORT7 unconnected is unused.
ROW0 Row Input from Key Matrix. Leave ROW0 unconnected or connect to GND if unused.
ROW1 Row Input from Key Matrix. Leave ROW1 unconnected or connect to GND if unused.
EP
2
C-Compatible, Serial-Data I/O
2
C-Compatible, Serial-Clock Input
Positive Supply Voltage. Bypass VCC to GND with a 0.047µF or higher ceramic capacitor.
Exposed Pad (TQFN only). EP internally is connected to GND. Connect EP to a ground plane
to increase thermal performance.
Loading...