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3. TECHNICAL BRIEF
3.5 External memory interface
A. MSM7227
The MSM7227 device was designed to provide two distinct memory interfaces. EBI1 was targeted for
supporting DDR synchronous memory devices. EBI2 was targeted towards supporting slower
asynchronous devices such as LCD, NAND flash, SRAM, NOR flash etc. To support the high-bandwidth,
high-density, and low-latency requirements of the advanced on-chip applications, the MSM7227 IC
has two high-speed, high-performance memory slave interfaces: the external bus interface 1 (EBI1)
and the stack memory interface (SMI). To achieve higher bandwidth and better use of the memory
device interface, the SMI accepts multiple commands for the external memory device. The SMI
interface acts as a slave device to all of the bus masters within the MSM device. The masters arbitrate
to gain access to the SMI, and upon obtaining the access, they issue commands to the SMI. The bus
masters are connected to the SMI through an advanced extensible interface (AXI) bus bridge (or
global interconnect block) and communicate over a 64-bit, non-blocking AXI bus protocol. The AXI
bus bridge provides the arbitration logic for all of the bus masters.
y
EBI1 Features
- Support for only low-power memories at 1.8-V I/O power supply voltage
- AXI bus frequencies up to 133 MHz
- A 16-bit/32-bit static and dynamic memory interface
y
DDR SDRAM interface features include:
- Supports both 32-bit DDR SDRAM devices, up to 133-MHz bus speed
- Supports auto precharge and manual precharge
- Supports partial refresh
- Separate CKE pin per chip-select to support partial operation mode
- Idle power down to save idling power consumption
y
EBI2 Features
- Support for asynchronous FLASH and SRAM(16bit & 8bit).
- Interface support for byte addressable 16bit devices(UB_N & LB_N signals).
- 2Mbytes of memory per chip select.
- Support for 8 bit/16bit wide NAND flash.
- Support for parallel LCD interfaces, port mapped of memory mapped(8 or 16 bit)
y
Multi Chip Package : DDR SDRAM and NAND Flash merged 1 package
y
2Gbit Mobile DDR SDRAM(64Mb x32) / 4Gbit NAND Flash
3. Technical Brief
Table#1. External memory interface for GD880
1.8V
1.8V
45ns / 400MHz
Hynix
NAND
Interface Spec
Product Gr
Part Name
Maker
Operation Voltage
(Flash / DRAM)
Speed
(Flash / DRAM)
H8BCS0UN0MCR-
4EM
SDRAM
4G (LB/256Mx16) NAND+4G (DDR400/16Mx4x2*2_2CS_2CKE) SDRAM
H8B ES0UU0MCR-4EM