MAX6958AAEE Maxim Integrated Products, MAX6958AAEE Datasheet - Page 15

• Manufacturer Part Number: MAX6958AAEE
• Description: LED Drivers 2-Wire Interfaced, 3 V to 5.5V, 4-Digit,
• Manufacturer: Maxim Integrated Products

Specifications of MAX6958AAEE

• Number Of Digits: 4
• Number Of Segments: 36
• Low Level Output Current: 275000 uA
• High Level Output Current: 30000 uA
• Operating Supply Voltage: 3 V to 5.5 V
• Maximum Supply Current: 6700 uA
• Maximum Power Dissipation: 667 mW
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: QSOP-16
• Minimum Operating Temperature: - 40 C

Figure 14. Keyscan Timing Diagram
pullup resistor from IRQ/SEG9 to a voltage no greater
than 5.5V when configuring IRQ/SEG9 as an interrupt
or logic output.
INPUT1 and INPUT2 can be individually configured as
either general-purpose logic inputs or as keyscan
inputs. In either mode, the input structure is the same—
CMOS logic inputs with internal pullup resistors. The
Table 16. Port Configuration Register Format
This is the bit assignment:
Read GPIO register
Write GPIO register
Here are the IRQ/SEG9 allocation options, determined by the settings of D7, D6, D5:
IRQ/SEG9 is logic 0 output
IRQ/SEG9 is logic 1 output
IRQ/SEG9 is active-low
IRQ
IRQ/SEG9 is active-high
IRQ
IRQ/SEG9 is segment
driver
DIG0/SEG0
DIG1/SEG1
DIG2/SEG2
DIG3/SEG3
INPUT1 Key0
INPUT2
FIRST TEST OF KEYS
9-Segment LED Display Drivers with Keyscan
Key4 Key5 Key6 Key7
1.28ms MULTIPLEX
A
Key1 Key2 Key3
MODE
CYCLE 1
5µs TO 315µs DIGIT PERIOD
B
1.28ms MULTIPLEX
______________________________________________________________________________________
CYCLE 2
THE FIRST HALF OF A 41ms KEYSCAN CYCLE
ADDRESS
2-Wire Interfaced, 3V to 5.5V, 4-Digit,
1.28ms MULTIPLEX
CODE
(HEX)
0x06
0x06
0x06
0x06
0x06
0x06
0x06
CYCLE 3
1.28ms MULTIPLEX
Read back
IRQ/SEG9
configuration
Configure
IRQ/SEG9
output
D7 D6 D5
0
0
0
0
1
CYCLE 4
0
0
1
1
X
X
0
1
0
1
1.28ms MULTIPLEX
Read back
INPUT 2
configuration
Configure
INPUT 2:
0 = logic input
1 = keyscan
CYCLE 15
SECOND TEST OF KEYS
D4
X
X
X
X
X
t
DEBOUNCE
C
Key0 Key1 Key2 Key3
Key4 Key5 Key6 Key7
1.28ms MULTIPLEX
pullups are always enabled, even in shutdown. Ensure
these inputs are either close to V+ or open circuit for
minimum shutdown supply current. If both INPUT1 and
INPUT2 are assigned to keyscan, then eight keys can
be debounced. If only INPUT1 or INPUT2 is assigned
to keyscan, then only four keys can be debounced.
CYCLE 16
Read back
INPUT 1
configuration
Configure
INPUT 1:
0 = logic input
1 = keyscan
REGISTER DATA
D
INTERRUPT ASSERTED IF REQUIRED
KEY DEBOUNCED REGISTER UPDATED
D3
1.28ms MULTIPLEX
X
X
X
X
X
CYCLE 1
INPUT2
logic level
THE SECOND HALF OF A 41ms KEYSCAN CYCLE
1.28ms MULTIPLEX
CYCLE 2
D2
X
X
X
X
X
X
INPUT1
logic level
1.28ms MULTIPLEX
CYCLE 15
D1
X
X
X
X
X
X
START OF NEXT KEYSCAN CYCLE
1.28ms MULTIPLEX
IRQ status
( 1 = i nter rup t)
CYCLE 16
D0
X
X
X
X
X
X
A
E
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