sx1502i088trt Semtech Corporation, sx1502i088trt Datasheet - Page 28

• Manufacturer Part Number: sx1502i088trt
• Description: 4/8/16 Channel Low Voltage Gpio With Nint And Nreset
• Manufacturer: Semtech Corporation

ADVANCED COMMUNICATIONS & SENSING
6.2.2
When the max IOL spec is not enough it is possible to drive simultaneously multiple I/Os connected together
hence increasing the total sink capability.
Example: on an SX1502, by driving an LED with both IO[2] and IO[3] one can sink up to 24+24 =48mA.
Driving an LED with multiple I/Os can also be used to implement more intensity steps for the LED.
Example: with two I/Os capable of sinking each 24mA the LED can sink a total of 0mA (no I/O set to “0”), 24mA
(one I/O set to “0”) or 48mA (both I/Os set to “0”) => 3 LED intensity steps ( 4 steps with 3 I/Os, 5 steps with 4
I/Os, etc)
6.3
SX1501, SX1502, and SX1503 can be used to implement keypad applications up to 8x8 matrix (i.e. 64 keys)
Example: We want to implement a 4x4matrix keypad on SX1502
6.4
Because of their I/O banks with independent supply voltages between 1.2V and 5.5V, the SX1502 and SX1503
can be easily used to perform level shifting of signals from one I/O bank to an other (uC reads I/O from one I/O
bank and sends it back to the other I/O bank)
This can save significant BOM cost in a final application where only a few slow signals need to be level-shifted.
Rev 7 – 2
1. Set all I/Os as inputs with internal pull-up (RegDir = 0xFF, RegPullUp = 0xFF)
2. Set NINT to be triggered on any IO’s falling edge (RegInterruptMask = 0x00, RegSenseHigh = 0xAA,
3. When NINT goes low read RegData (or RegInterruptSource) to know the X:Y coordinates of the button
4. Clear NINT (RegInterruptSource = 0xFF, can be done automatically on SX1503 depending on
5. Restart from point 3
Keypad Implementation
Level Shifter Implementation Hints
LED Intensity Control
RegSenseLow = 0xAA)
which has been pressed.
RegAdvanced setting)
nd
Oct. 2008
Figure 14 – 4x4 keypad connection to SX1502
IO[7-0] as inputs with internal pull-ups enabled
SX1502
IO7
IO6
IO5
IO4
IO3
IO2
IO1
IO0
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4/8/16 Channel Low Voltage GPIO
SX1501/SX1502/SX1503
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