P89LPC915HDH NXP Semiconductors, P89LPC915HDH Datasheet - Page 39

• Manufacturer Part Number: P89LPC915HDH
• Description: MCU 8BIT 80C51 2K FLASH, TSSOP14
• Manufacturer: NXP Semiconductors

Specifications of P89LPC915HDH

• Controller Family/series: (8051) 8052
• Core Size: 8bit
• No. Of I/o's: 14
• Program Memory Size: 2KB
• Ram Memory Size: 256Byte
• Cpu Speed: 18MHz
• Oscillator Type: Internal Only
• No. Of Timers: 4
• Digital Ic: RoHS Compliant

NXP Semiconductors
P89LPC915_916_917_5
Product data sheet
8.15.3 Total Power-down mode
8.16 Reset
8.17 Timers/counters 0 and 1
Some chip functions continue to operate and draw power during Power-down mode,
increasing the total power used during power-down. These include: Brownout detect,
watchdog timer, comparators (note that comparators can be powered down separately),
and RTC/system timer. The internal RC oscillator is disabled unless both the RC oscillator
has been selected as the system clock and the RTC is enabled.
This is the same as Power-down mode except that the brownout detection circuitry and
the voltage comparators are also disabled to conserve additional power. The internal RC
oscillator is disabled unless both the RC oscillator has been selected as the system clock
and the RTC is enabled. If the internal RC oscillator is used to clock the RTC during
power-down, there will be high power consumption. Please use an external low frequency
clock to achieve low power with the RTC running during power-down.
The P1.5/RST pin can function as either an active-LOW reset input or as a digital input,
P1.5. The RPE (Reset Pin Enable) bit in UCFG1, when set to ‘1’, enables the external
reset input function on P1.5. When cleared, P1.5 may be used as an input pin.
Remark: During a power-up sequence, the RPE selection is overridden and this pin
always functions as a reset input. An external circuit connected to this pin should not
hold this pin LOW during a power-on sequence as this will keep the device in reset.
After power-up this input will function either as an external reset input or as a digital input
as defined by the RPE bit. Only a power-up reset will temporarily override the selection
defined by RPE bit. Other sources of reset will not override the RPE bit.
Reset can be triggered from the following sources:
For every reset source, there is a flag in the Reset Register, RSTSRC. The user can read
this register to determine the most recent reset source. These flag bits can be cleared in
software by writing a ‘0’ to the corresponding bit. More than one flag bit may be set:
The P89LPC915/916/917 have two general purpose counter/timers which are upward
compatible with the standard 80C51 Timer 0 and Timer 1. Both can be configured to
operate either as timers or event counters. An option to automatically toggle the T0 and/or
T1 pins upon timer overflow has been added.
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External reset pin (during power-up or if user configured via UCFG1);
Power-on detect;
Brownout detect;
Watchdog timer;
Software reset;
UART break character detect reset.
During a power-on reset, both POF and BOF are set but the other flag bits are
cleared.
For any other reset, previously set flag bits that have not been cleared will remain set.
Rev. 05 — 15 December 2009
8-bit microcontrollers with accelerated two-clock 80C51 core
P89LPC915/916/917
© NXP B.V. 2009. All rights reserved.
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