HT67F60A Datasheet, PDF (67/242 Pages) Holtek Semiconductor Inc – TinyPowerTM A/D Flash MCU with LCD & EEPROM

HT67F60A/HT67F70A
TinyPower^TM A/D Flash MCU with LCD & EEPROM
Wake-up
To minimise power consumption the device can enter the SLEEP or any IDLE Mode, where the
CPU will be switched off. However, when the device is woken up again, it will take a considerable
time for the original system oscillator to restart, stablise and allow normal operation to resume.
After the system enters the SLEEP or IDLE Mode, it can be woken up from one of various sources
listed as follows:
• An external reset
• An external falling edge on Port A
• A system interrupt
• A WDT overflow
As the main reason for entering the SLEEP or IDLE Mode is to keep the current consumption of
these devices to as low a value as possible, perhaps only in the order of several micro-amps except
in the IDLE1 Mode, there are other considerations which must also be taken into account by the
circuit designer if the power consumption is to be minimised. Special attention must be made to
the I/O pins on these devices. All high-impedance input pins must be connected to either a fixed
high or low level as any floating input pins could create internal oscillations and result in increased
current consumption. This also applies to devices which have different package types, as there may
be unbonded pins. These must either be setup as outputs or if setup as inputs must have pull-high
resistors connected.
Care must also be taken with the loads, which are connected to I/O pins, which are setup as outputs.
These should be placed in a condition in which minimum current is drawn or connected only to
external circuits that do not draw current, such as other CMOS inputs. Also note that additional
standby current will also be required if the configuration options have enabled the LXT or LIRC
oscillator.
In the IDLE1 Mode the system oscillator is on, if the system oscillator is from the high speed system
oscillator, the additional standby current will also be perhaps in the order of several hundred micro-amps.
Rev. 1.10
67
December 01, 2016