HT66F03T3 データシートの表示（PDF） - Holtek Semiconductor

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HT66F03T3

8-Bit Flash MCU with RF Transmitter

Holtek Semiconductor 

HT66F03T3/HT68F03T3

8-Bit Flash MCU with RF Transmitter

Functional Description

As these device packages contain different chips internally, for a detailed functional description, users

must refer to the relevant datasheets for the related MCU. The following table shows which individual

devices are inside each package.

Device

HT66F03T3

HT68F03T3

MCU

HT66F03

HT68F03

Multi-chip Internal Devices

One of the MCU I/O pins, PA4, is internally connected to the data input pin, DIN, of RF transmitter

chip and should therefore be setup as an output by the MCU. This pin is used to generate the encoding

data. There are some special considerations which need to be taken into account when using these

devices. These points will be mentioned in the hardware and software consideration sections.

Hardware Considerations

As these devices are composed of an individual MCU and RF Transmitter, using them together

requires the user to take care of some special points.

Absolute Maximum Ratings

The Absolute Maximum Ratings must be checked for discrepancies and the necessary care taken in

device handling and usage.

Power Supply

Examination of the block diagram will reveal that the Power Supply and Ground pins of the RF

Transmitter and MCU are independent and must be connected together if they are to share the same

power supply. If the same power supply is to be used for both chips then care must be taken as the

maximum power supply voltage of the RF Transmitter is less than the maximum MCU power supply

voltage. Also note that higher MCU system clock frequencies may require MCU power supply

voltages that exceed the RF Transmitter maximum power supply voltage. For this reason it will not be

possible to operate the MCU at its maximum system clock frequency if the MCU shares the same

power supply as the RF Transmitter.

When calculating the total current consumption of the device, the specified currents of the MCU part

and the RF part in the DC specifications, must be added together. Similarly, the standby current is the

sum of the two individual chip standby currents.

Operation

The RF data to be transmitted is derived from the PA4 line. When the PA4 line is high the RF

Transmitter will transmit it data allowing users to program their encoded data on this line. If the RF

transmitter is in its standby mode then there will be a delay of about 500us before transmission begins.

When the device is transmitting, a synchronising signal will be generated on the CREF pin which can

be connected externally to an MCU I/O pin for calibration of the MCU internal RC oscillator. To avoid

the RF circuits entering an unknown state, pin PA4 should be setup as an output as soon as possible

after power-on.

To minimise power consumption, only when PA4 is high, can the RF signal be transmitted and the

reference clock on CREF be generated. If no data transitions are generated on PA4 for 300~500ms, the

transmitter will enter a standby state and the RF circuits will be switched off along with the internal

PLL to save power. The signal generated on the CREF pin will also remain at a low level. The internal

PLL function is used to generate the RF frequency with a multiplier of 32 times the crystal frequency.

The relationship is: RF frequency = 32 x Crystal frequency. Therefore a 9.84375MHz crystal will

Rev. 1.30

9

July 4, 2011

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