HT46R064D/065D/066D
Enhanced A/D Type 8-Bit OTP MCU with LED Driver
Crystal Oscillator C1 and C2 Values
Crystal Frequency
12MHz
C1
8pF
C2
10pF
10pF
10pF
100pF
8MHz
8pF
4MHz
8pF
1MHz
100pF
Note: C1 and C2 values are for guidance only.
Crystal Recommended Capacitor Values
External RC Oscillator - ERC
Using the ERC oscillator only requires that a resistor, with a value between 24kW and 1.5MW, is
connected between OSC1 and VDD, and a capacitor is connected between OSC and ground,
providing a low cost oscillator configuration. It is only the external resistor that determines the
oscillation frequency; the external capacitor has no influence over the frequency and is connected for
stability purposes only. Device trimming during the manufacturing process and the inclusion of
internal frequency compensation circuits are used to ensure that the influence of the power supply
voltage, temperature and process variations on the oscillation frequency are minimised. As a
resistance/frequency reference point, it can be noted that with an external 120kW resistor connected
and with a 5Vvoltage power supply and temperature of 25 degrees, the oscillator will have a frequency
of 4MHz within a tolerance of 2%. Here only the OSC1 pin is used, which is shared with I/O pin PA6,
leaving pin PA5 free for use as a normal I/O pin.
External RC Oscillator - ERC
Internal RC Oscillator - HIRC
The internal RC oscillator is a fully integrated system oscillator requiring no external components. The
internal RC oscillator has three fixed frequencies of either 4MHz, 8MHz or 12MHz. Device trimming
during the manufacturing process and the inclusion of internal frequency compensation circuits are
used to ensure that the influence of the power supply voltage, temperature and process variations on
the oscillation frequency are minimised. As a result, at a power supply of either 3V or 5V and at a
temperature of 25 degrees, the fixed oscillation frequency of 4MHz, 8MHz or 12MHz will have a
tolerance within 2%. Note that if this internal system clock option is selected, as it requires no external
pins for its operation, I/O pins PA5 and PA6 are free for use as normal I/O pins.
Internal RC Oscillator - HIRC
Rev. 1.00
28
January 12, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
