Architecture
1348
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Serial ATA (SATA) Controller
28.2 Architecture
This section discusses the architecture of the Serial ATA Controller. The Serial ATA Controller supports
Advanced Host Controller Interface (AHCI) operation only. It does not support the Legacy mode of
operation. Since the controller complies with the AHCI standard (version 1.1) the details of its operation is
detailed within the AHCI version 1.1 specification. See the specification for the general behavior of the
SATA Core operation. The SATA Controller supported within the Freon device has a single HBA port.
28.2.1 Clock Control
The SATA controller uses two internal clocks (SYSCLK2 and SYSCLK4) and one external differential
clock (REFCLKP/N) for its operation. SATA controller access to CPU and its resources is implemented
through, SYSCLK2 (PLL0 output frequency divided by 2). SYCLK2 to the SATA controller is gated by the
PSC and is required to be enabled prior to accessing the SATA controller. SYCLK4 (PLL0 output
frequency divided by 4), is the keep alive clock and is always ON.
A high quality low jitter external differential clock is required as a source clock input for the PHY and the
frequency of the input clock should be between 75MHz and 375 MHz (depending upon the supported
multiplier used). Maximum Jitter should not exceed 50ps pk-pk. Duty cycle must be between 40 and 60%.
Nominal Rise/fall time should be 700 ps.
This input frequency requirement is dependent upon the supported PHY PLL multiplier value. The MPY
field of the port PHY control register (P0PHYCR) is programmed with the PLL multiplier value based on
the input frequency clock. Note that the PHY PLL output frequency should be exactly 1.5GHz (for both 3
and 1.5 Gbits/Sec line rate) and its accuracy is very important to the operation of the SATA controller.
shows the MPY bit field of P0PHYCR for supported PHY PLL multiplier values.
Table 28-1. MPY Bit Field of P0PHYCR
MPY Bit Field Value
Effect
0
Reserved
1h
5×
2h
6×
3h
Reserved
4h
8×
5h
10×
6h
12×
7h
12.5×
8h
15×
9h
20×
Ah
25×
Bh-Fh
Reserved