LPC2468FBD208,551 NXP Semiconductors, LPC2468FBD208,551 Datasheet - Page 72

• Manufacturer Part Number: LPC2468FBD208,551
• Description: IC ARM7 MCU FLASH 512K 208-LQFP
• Manufacturer: NXP Semiconductors
• Series: LPC2400r

Specifications of LPC2468FBD208,551

• Program Memory Type: FLASH
• Program Memory Size: 512KB (512K x 8)
• Package / Case: 208-LQFP
• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 72MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, Microwire, MMC, SPI, SSI, SSP, UART/USART, USB OTG
• Peripherals: Brown-out Detect/Reset, DMA, I²S, POR, PWM, WDT
• Number Of I /o: 160
• Ram Size: 98K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: LPC24
• Core: ARM7TDMI-S
• Data Bus Width: 16 bit, 32 bit
• Data Ram Size: 98 KB
• Interface Type: CAN/I2S/ISP/SSP/UART/USB
• Maximum Clock Frequency: 72 MHz
• Number Of Programmable I/os: 160
• Number Of Timers: 6
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: MDK-ARM, RL-ARM, ULINK2, IRD-LPC2468-DEV, SAB-TFBGA208, KSK-LPC2468-PL
• Development Tools By Supplier: OM10100
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• On-chip Dac: 1-ch x 10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 622-1025 - KIT DEV IND REF DESIGN LPC2468622-1024 - BOARD SCKT ADAPTER FOR TFBGA208568-4358 - DISPLAY QVGA TFT FOR OM10100568-4309 - BOARD EXTENSION LPCSTICK568-4308 - EVAL LPC-STICK WITH LPC2468MCB2400U - BOARD EVAL MCB2400 + ULINK2MCB2400 - BOARD EVAL FOR NXP LPC246X SER622-1005 - USB IN-CIRCUIT PROG ARM7 LPC2K
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 568-4261; 935282457551; LPC2468FBD208-S

NXP Semiconductors
6. Low-power operation
UM10237_4
User manual
5.4.2 Read buffers
5.5 Memory controller state machine
The write buffers are flushed whenever:
Note: For dynamic memory, the smallest buffer flush is a quadword of data. For static
memory, the smallest buffer flush is a byte of data.
Read buffers are used to:
Read buffer operation:
A buffer filled by performing a read from memory is marked as not-dirty (not containing
write data) and its contents are not flushed back to the memory controller unless a
subsequent AHB transfer performs a write that hits the buffer.
The memory controller state machine comprises a static memory controller and a dynamic
memory controller.
In many systems, the contents of the memory system have to be maintained during
low-power sleep modes. The EMC provides a mechanism to place the dynamic memories
into self-refresh mode.
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If the buffers are enabled, an AHB write operation writes into the Least Recently Used
(LRU) buffer, if empty.
If the LRU buffer is not empty, the contents of the buffer are flushed to memory to
make space for the AHB write data.
If a buffer contains write data it is marked as dirty, and its contents are written to
memory before the buffer can be reallocated.
The memory controller state machine is not busy performing accesses to external
memory.
The memory controller state machine is not busy performing accesses to external
memory, and an AHB interface is writing to a different buffer.
Buffer read requests from memory. Future read requests that hit the buffer read the
data from the buffer rather than memory, reducing transaction latency.
Convert all read transactions into quadword bursts on the external memory interface.
This enhances transfer efficiency for dynamic memory.
Reduce external memory traffic. This improves memory bandwidth and reduces
power consumption.
If the buffers are enabled and the read data is contained in one of the buffers, the read
data is provided directly from the buffer.
If the read data is not contained in a buffer, the LRU buffer is selected. If the buffer is
dirty (contains write data), the write data is flushed to memory. When an empty buffer
is available the read command is posted to the memory.
Rev. 04 — 26 August 2009
Chapter 5: LPC24XX External Memory Controller (EMC)
UM10237
© NXP B.V. 2009. All rights reserved.
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