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

generate an RF frequency of 315MHz and a13.56MHz crystal will generate an RF frequency of

433.92MHz. All PLL circuits are contained within the device and the only external component

required is a suitable crystal.

Power Down and Wake up

It is important to note that if the MCU is powered down or placed into a low power mode to conserve

power, that the RF Transmitter may continue running and will consume a certain amount of power.

Before powering down the MCU it is important to carefully manage the PA4 pin to ensure the

RF-Transmitter enters its power down state.

Unbonded MCU pins

Examination of the relevant MCU datasheet will reveal that not all of the MCU I/O port lines are

bonded out to external pins. As a result special attention regarding initialisation procedures should be

paid to these port lines. Users should therefore ensure that these I/O pins are setup as inputs with pull

high resistors or as outputs to avoid additional power consumption resulting from floating input pins.

Programming Considerations

As MCU I/O pin PA4 is used to control the RF transmitter function, care must be taken to manage this

pin correctly in the application program. As line PA4 is used to send data to the RF circuitry this

multi-function pin line must be correctly setup to function as logic output. To avoid erroneous

operation of the RF circuits this line should be setup as an output immediately after power-on.

If the CREF pin is connected externally to an MCU I/O pin for synchronisation purposes, then this pin

must be properly setup as a logic input immediately after power on.

As the MCU will be powered down independently of the RF Transmitter Peripheral Module, care must be

taken to ensure that the MCU first clears its PA4 line to zero before powering down. This will allow the RF

Transmitter Peripheral Module to enter its standby state and thus keep power consumption to a minimum.

Application Circuits

Note:

1. A 9.84375MHz crystal is used for an RF frequency of 315MHz

A 13.56MHz crystal is used for an RF frequency of 433.92MHz

2. The extra LC filter on the PAOUT pin can reduce second order harmonics

3. The bracketed L and C values are for 433.92MHz operation

Rev. 1.30

10

July 4, 2011

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