JAJSLG0B April 2021 – March 2023 TSER953
PRODUCTION DATA
The input on the TSER953 GPIO pins can be forwarded to compatible deserializers over the V3Link interface. Up to four GPIOs are supported in the forward direction.
The timing for the forward channel GPIO is dependent on the number of GPIOs assigned at the serializer. When a single GPIO input from the TSER953 serializer is linked to a compatible deserializer GPIO output, the value is sampled at every forward channel transmit frame. Two linked GPIO are sampled every two forward channel frames, and three or four linked GPIO are sampled every five frames. The typical latency for the GPIO is approximately 225 ns but will vary with the length of the cable. As the information is spread over multiple frames, the jitter is typically increased on the order of the sampling period (number of forward channel frames). TI recommends that the user maintain a 4x oversampling ratio for linked GPIO throughput. For example, when operating in 4-Gbps synchronous mode with REFCLK = 25 MHz, the maximum recommended GPIO input frequency based on the number of GPIO linked over the forward channel is shown in Table 7-5.
NUMBER OF LINKED FORWARD CHANNEL GPIOs (FC_GPIO_EN) |
SAMPLING FREQUENCY (MHz) AT V3Link LINE RATE = 4 Gbps |
MAXIMUM RECOMMENDED FORWARD CHANNEL GPIO FREQUENCY (MHz) | TYPICAL LATENCY (ns) | TYPICAL JITTER (ns) |
---|---|---|---|---|
1 | 100 | 25 | 225 | 12 |
2 | 50 | 12.5 | 225 | 24 |
4 | 20 | 5 | 225 | 60 |