Holtek HT67F86A Application Manuallines

HT67F86A Internal RTC Application Guidelines
D/N: AN0448E

Introduction

One special feature of the Holtek 8-bit Flash MCU, the HT67F86A, is that it includes an
ultra-low power consumption RTC oscillator and an LCD driver. To meet the demands for
low power consumption applications, the device's internal RTC has a standby power
consumption of lower than 1µA at an operating voltage of 3V. The integrated LCD driver
can drive dot matrix LCD display applications of up to 1024 pixels, which can be used with
various display configurations and font settings. With the increasing trends of mobile
device applications such as cellphones and tablets, in addition to being utilised in
industrial control and consumer products, the ultra-low standby power consumption
performance is also an especially important consideration in battery-powered applications.
The MCU's internal RTC oscillator forms an excellent solution for applications which
require a real time clock function as it reduces the need for an external timing IC with the
resulting reductions in cost and design simplification. This application note will introduce
the Holtek MCU internal RTC oscillator characteristics and application guidelines.

Functional Description

Oscillators

The HT67F86A provides 3 frequency oscillation sources, namely the HXT, HITC and LXT
oscillators. Users can select their desired system frequency, f
program. The LXT provides an f
commonly for applications requiring an RTC real-time clock. Additionally, the MCU can
enter the IDLE2 or SLEEP power saving modes also using the application program to
implement different standby power consumption power down modes. The related
registers are listed in the following table, refer to the Oscillators section in the datasheet
for more detailed information.
Register
Name
SCC
HIRCC
HXTC
LXTC
AN0448E V1.00
HT67F86A Internal RTC Application Guidelines
frequency of 32768Hz for various MCU clocks, but more
L
7 6 5
CKS2 CKS1 CKS0
— — —
— — —
— — —

System Operating Mode Control Registers List

1/7
using their application
SYS,
Bit
4 3 2
— FHS —
— HIRC1 HIRC0
— — HXTM
— — —
1 0
FHIDEN FSIDEN
HIRCF HIRCEN
HXTF HXTEN
LXTF LXTEN
January 16, 2017