MTX1
Manual
Temperature Sensor
The temperature sensor is the MCP9701ATE/TT from Microchip. It is connected to pin A1,
and can be disconnected by using a solder jumper. It can sense from 10C to 125C, though the high
temperature is limited to the maximum PCB temperature. It has an accuracy of +/ 2C (max.) and it
outputs 19.5mV/C. It consumes only 6uA (typ.). For more information on this IC, please consult the
datasheet.
8channel Lowside / Relay Driver
The 8channel lowside / relay driver is the MAX4820 from Maxim. The outputs are opendrain.
Each channel can drive low at 70mA each. Channels can be connected together to increase the
current capability. All channels have kickback protection diodes, allowing them to driver relays. Note
that solder jumper J2 must be connected for kickback protection to be available. All eight outputs,
along with 3.3V (regulated Vcc) and ~5V (external voltage), are routed to a 10pin header. Thus,
devices that use either 3.3V or 5V (ie: 5V relay, 5V LCD backlight) are supported.
Voltages greater
than 5.5V on the external power input header require J2 to be disconnected, which will disable the relay
driver kickback protection.
The IC
is connected to SPI F and can be disconnected using the solder
jumpers. Note that MISO is not connected, so the XMEGA cannot read from the IC. Also note that the
SPI F SS line is not used as the chip select, but instead, Q2 is used. Thus, it is necessary to configure
the SS pin as an output, or enable the pullup and leave it as an input so that SPI will operate as a
master. The maximum operating speed is 2MHz. The protocol is very simple; essentially just a shift
register. A simple driver is provided in the ASF template. For more information on this IC, please
consult the datasheet.
LEDs
There are four LEDs connected to pins D0D3, and can be disconnected by using the solder
jumpers. The LEDs are on when the outputs are high. The LEDs are connected to ground through 249
ohm series resistors.
External 1MB lowpower SRAM (optional)
An external 1 MB lowpower SRAM module is available separately.
* 8Mbit (1024 x 8) static RAM
* Cypress CY62158EV30 IC
* 45ns
* 2.2V3.6V
* 18mA (25mA max) @ max speed
* 2uA (8uA max) when not selected
* 40C to +85C
* 2 latches for address lines (20bit)
* dedicated 8bit data lines
* Measures 34.6mm x 25.0mm (1.36" x 0.98")
* Fits EBI header on MTX1 development board
June 2, 2015
12
