P89LPC912FDH NXP Semiconductors, P89LPC912FDH Datasheet - Page 29

• Manufacturer Part Number: P89LPC912FDH
• Description: MCU 8BIT 80C51 1K FLASH, TSSOP14
• Manufacturer: NXP Semiconductors

Specifications of P89LPC912FDH

• Controller Family/series: (8051) 8052
• Core Size: 8bit
• No. Of I/o's: 12
• Program Memory Size: 1KB
• Ram Memory Size: 128Byte
• Cpu Speed: 18MHz
• Oscillator Type: External, Internal
• No. Of Timers: 4
• No. Of: RoHS Compliant

NXP Semiconductors
P89LPC912_913_914_5
Product data sheet
8.3.6 Clock output (P89LPC912, P89LPC913)
8.4 On-chip RC oscillator option
8.5 Watchdog oscillator option
8.6 External clock input option (P89LPC912, P89LPC913)
The P89LPC912 supports a user selectable clock output function on the XTAL2/CLKOUT
pin when crystal oscillator is not being used. This condition occurs if another clock source
has been selected (on-chip RC oscillator, watchdog oscillator, external clock input on X1)
and if the Real-Time clock is not using the crystal oscillator as its clock source. This allows
external devices to synchronize to the P89LPC912. This output is enabled by the ENCLK
bit in the TRIM register. The frequency of this clock output is
clock output is not needed in Idle mode, it may be turned off prior to entering Idle, saving
additional power.
The P89LPC912/913/914 has a 6-bit TRIM register that can be used to tune the
frequency of the RC oscillator. During reset, the TRIM value is initialized to a factory
preprogrammed value to adjust the oscillator frequency to 7.373 MHz,
temperature. End-user applications can write to the TRIM register to adjust the on-chip
RC oscillator to other frequencies.
The watchdog has a separate oscillator which has a frequency of 400 kHz. This oscillator
can be used to save power when a high clock frequency is not needed.
In this configuration, the processor clock is derived from an external source driving the
XTAL1/P3.1 pin. The rate may be from 0 Hz up to 12 MHz. The XTAL2/P3.0 pin may be
used as a standard port pin or a clock output. When using an oscillator frequency
above 12 MHz, the reset input function of P1.5 must be enabled. An external circuit
is required to hold the device in reset at power-up until V
specified level. When system power is removed, V
specified operating voltage. When using an oscillator frequency above 12 MHz, in
some applications, an external brownout detect circuit may be required to hold the
device in reset when V
Rev. 05 — 28 September 2007
DD
falls below the minimum specified operating voltage.
8-bit microcontrollers with two-clock 80C51 core
P89LPC912/913/914
DD
will fall below the minimum
1
DD
2
that of the CCLK. If the
has reached its
© NXP B.V. 2007. All rights reserved.
1 % at room
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