LPC2458FET180,551 NXP Semiconductors, LPC2458FET180,551 Datasheet - Page 657

• Manufacturer Part Number: LPC2458FET180,551
• Description: IC ARM7 MCU FLASH 512K 180TFBGA
• Manufacturer: NXP Semiconductors
• Series: LPC2400r

Specifications of LPC2458FET180,551

• 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: 136
• Program Memory Size: 512KB (512K x 8)
• Program Memory Type: FLASH
• 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
• Package / Case: 180-TFBGA
• Processor Series: LPC24
• Core: ARM7TDMI-S
• Data Bus Width: 32 bit
• Data Ram Size: 98 KB
• Interface Type: CAN, Ethernet, I2C, I2S, IrDA, SPI, SSP, UART, USB
• Maximum Clock Frequency: 72 MHz
• Number Of Programmable I/os: 136
• Number Of Timers: 4
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: MDK-ARM, RL-ARM, ULINK2, SAB-TFBGA180
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• On-chip Dac: 10 bit, 1 Channel
• Package: 180TFBGA
• Device Core: ARM7TDMI-S
• Family Name: LPC2000
• Maximum Speed: 72 MHz
• For Use With: 622-1023 - BOARD SCKT ADAPTER FOR TFBGA180622-1005 - USB IN-CIRCUIT PROG ARM7 LPC2K
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details
• Other names: 568-4258; 935282454551; LPC2458FET180-S

NXP Semiconductors
UM10237_4
User manual
6.7.2 Prescaler Integer Register (PREINT - 0xE002 4080)
6.7.3 Prescaler Fraction Register (PREFRAC - 0xE002 4084)
6.7.4 Example of Prescaler Usage
Table 579. Reference Clock Divider registers
This is the integer portion of the prescale value, calculated as:
PREINT = int (PCLK/32768) - 1. The value of PREINT must be greater than or equal to 1.
Table 580: Prescaler Integer register (PREINT - address 0xE002 4080) bit description
This is the fractional portion of the prescale value, and may be calculated as:
PREFRAC = PCLK - ((PREINT + 1) x 32768).
Table 581: Prescaler Integer register (PREFRAC - address 0xE002 4084) bit description
In a simplistic case, the PCLK frequency is 65.537 kHz. So:
PREINT = int (PCLK / 32768) - 1 = 1 and
PREFRAC = PCLK - ([PREINT + 1] x 32768) = 1
With this prescaler setting, exactly 32,768 clocks per second will be provided to the RTC
by counting 2 PCLKs 32,767 times, and 3 PCLKs once.
In a more realistic case, the PCLK frequency is 10 MHz. Then,
PREINT = int (PCLK / 32768) - 1 = 304 and
PREFRAC = PCLK - ([PREINT + 1] x 32768) = 5,760.
In this case, 5,760 of the prescaler output clocks will be 306 (305+1) PCLKs long, the rest
will be 305 PCLKs long.
In a similar manner, any PCLK rate greater than 65.536 kHz (as long as it is an even
number of cycles per second) may be turned into a 32 kHz reference clock for the RTC.
The only caveat is that if PREFRAC does not contain a zero, then not all of the 32,768 per
second clocks are of the same length. Some of the clocks are one PCLK longer than
others. While the longer pulses are distributed as evenly as possible among the remaining
Name
PREINT
PREFRAC 15
Bit
12:0
15:13
Bit
14:0
15
Symbol
Prescaler Integer Contains the integer portion of the RTC prescaler value.
-
Symbol
Prescaler
Fraction
-
Size
13
Description
Prescale Value, integer portion
Prescale Value, fractional portion
Rev. 04 — 26 August 2009
Chapter 26: LPC24XX Real-Time Clock (RTC) and battery RAM
Description
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
Description
Contains the integer portion of the RTC prescaler value.
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
Access
R/W
R/W
UM10237
© NXP B.V. 2009. All rights reserved.
0xE002 4080
0xE002 4084
Address
657 of 792
Reset
Value
0
NA
Reset
Value
0
NA