P89LPC985 datasheet(42/85 Pages) NXP

42 / 85 page

P89LPC980_982_983_985_2

Preliminary data sheet

Rev. 02 — 8 February 2010

42 of 85

NXP Semiconductors

P89LPC980/982/983/985

8-bit microcontroller with accelerated two-clock 80C51 core

For correct activation of brownout detect, the VDD rise and fall times must be observed.

Please see Table 13 “Static characteristics” for specifications.

7.17.2 Power-on detection

The Power-on detect has a function similar to the brownout detect, but is designed to work

as power comes up initially to ensure that the device is reset from Power-on. The POF

flag in the RSTSRC register is set to indicate an initial power-up condition. The POF flag

will remain set until cleared by software.

7.17.3 Power reduction modes

The P89LPC980/982/983/985 supports three different power reduction modes. These

modes are Idle mode, Power-down mode, and total Power-down mode.

7.17.3.1

Idle mode

Idle mode leaves peripherals running in order to allow them to activate the processor

when an interrupt is generated. Any enabled interrupt source or reset may terminate Idle

mode.

7.17.3.2

Power-down mode

The Power-down mode stops the oscillator in order to minimize power consumption.

Brownout detection circuitry is disabled. The P89LPC980/982/983/985 exits Power-down

mode via any reset, or certain interrupts.

Some chip functions continue to operate and draw power during Power-down mode,

increasing the total power used during power-down. These include: watchdog timer,

comparators and RTC/system timer (note that watchdog timer, comparators and

RTC/system timer can be powered down separately). The internal RC oscillator is

disabled unless both the RC oscillator has been selected as the system clock and the

RTC is enabled.

7.17.3.3

Total Power-down mode

The total Power-down mode is a deeper power reduction mode. Brownout detection

circuitry and analog comparators are disabled, as well as the internal RC oscillator.

Please use an external low frequency clock or 25 KHz watchdog oscillator to achieve low

power with the RTC running during power-down.

7.17.4 Regulators

Internal regulators can be adjusted automatically to minimize power consumption during

different power reduction modes. In normal or Idle modes, power consumption can be

further reduced by configuring PMUCON register.

In normal or Idle mode, regulators have two operation modes: high speed mode and low

current mode.

The regulators can be configured to low current mode to reduce the power consumption.

After power-on-reset, internal regulators enter into high speed mode as default. PMUCON

current mode to high speed mode, HCOK bit is used to indicate whether the switching is

ready. When set, it means switch successfully.

P89LPC985 Datasheet(PDF) 42 Page - NXP Semiconductors

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