NXP Semiconductors MPC5644A, Reference Manual, Page: 213 / 1735

General-Purpose Static RAM (SRAM)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 213
Chapter 11
General-Purpose Static RAM (SRAM)
11.1 Introduction
The MPC5644A includes 192 KB of general-purpose SRAM. The first 32 KB of SRAM is powered by its
own power supply pin during standby operation.
11.2 Features
The SRAM controller includes these features:
• Supports read/write accesses mapped to the SRAM memory from any master
• 32-KB block powered by separate supply for standby operation
• Byte, halfword, word and doubleword addressable
• 7-bit ECC
11.3 Modes of operation
11.3.1 Normal (Functional) mode
Allows reads and writes of the SRAM memory arrays.
11.3.2 Standby mode
Preserves contents of the standby portion of the memory when the 1.2 V (V
DD
) power drops below the
level of the standby power supply voltage. There are two possible supplies for standby: 1.0 V directly from
the VSTBY pin and 2 – 5 volts (also on the VSTBY pin), which enables a standby regulator.
VSTBY pad needs an external RC to slower the ramp to atleast 100 us to prevent a false ESD trigger.
Updates to the standby portion of the SRAM are inhibited during system reset or during Standby Mode.
11.4 Block diagram
The SRAM block diagram is shown in Figure 11-1 .
Figure 11-1. SRAM Block Diagram
SRAM
160 KB
V
STBY
32 KB
V
DD
Standby Switch