Datasheet

AFE4490
SBAS602F –DECEMBER 2012–REVISED OCTOBER 2013 www.ti.com
PIN DESCRIPTIONS (continued)
NAME NO. FUNCTION DESCRIPTION
Output signal that indicates a PD sensor or cable fault.
PD_ALM/ADC Reset 23 Digital Can be connected to the port pin of an external microcontroller.
In ADC bypass mode, the PD_ALM pin can be used to bring out the ADC reset signal.
AFE-only reset input, active low.
RESET 29 Digital
Can be connected to the port pin of an external microcontroller.
RX_ANA_GND 3, 36, 40 Supply Rx analog ground pin. Connect to common board ground.
RX_ANA_SUP 33, 39 Supply Rx analog supply pin; 0.1-µF decoupling capacitor to ground
RX_DIG_GND 19, 32 Supply Rx digital ground pin. Connect to common board ground.
RX_DIG_SUP 31 Supply Rx digital supply pin; 0.1-µF decoupling capacitor to ground
RXOUTN 34 Analog External ADC negative input when in ADC bypass mode
RXOUTP 35 Analog External ADC positive input when in ADC bypass mode
SCLK 24 SPI SPI clock pin
SPISIMO 26 SPI SPI serial in master out
SPISOMI 25 SPI SPI serial out master in
SPISTE 27 SPI SPI serial interface enable
TX_CTRL_SUP 11 Supply Transmit control supply pin (0.1-µF decoupling capacitor to ground)
Transmitter reference voltage, 0.75 V default after reset.
TX_REF 9 Reference
Connect a 2.2-μF decoupling capacitor to ground.
TXN 14 Analog LED driver out B, H-bridge output. Connect to LED.
TXP 15 Analog LED driver out B, H-bridge output. Connect to LED.
Input common-mode voltage output.
Connect a series resistor (1 kΩ) and a decoupling capacitor (10 nF) to ground.
VCM 4 Reference
The voltage across the capacitor can be used to shield (guard) the INP, INM traces.
Expected voltage = 0.9 V.
VSS 8 Supply Substrate ground. Connect to common board ground.
Crystal oscillator pins.
XOUT 37 Digital Connect an external 8-MHz crystal between these pins with the correct load capacitor
(as specified by vendor) to ground.
Crystal oscillator pins.
XIN 38 Digital Connect an external 8-MHz crystal between these pins with the correct load capacitor
(as specified by vendor) to ground.
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