HT66FB30 datasheet(13/26 Pages) HOLTEK

13 / 26 page

HT66FB30/HT66FB40/HT66FB50/HT66FB60

Rev. 1.10

June 4, 2010

Functional Description

As these devices packages contain multiple internal

chips, for a detailed functional description, users must

refer to the relevant individual datasheets for both the

MCU and the SPI to USB chips. The following table

shows which individual devices are inside each pack-

age.

Device

MCU

SPI to USB Chip

HT66FB30

HT66F30

HT45B0K

HT66FB40

HT66F40

HT45B0K

HT66FB50

HT66F50

HT45B0K

HT66FB60

HT66F60

HT45B0K

Multi-chip Internal Devices

Although most of the functional description material will

be located in the individual datasheets, there are some

special considerations which need to be taken into ac-

count when using multi-chip devices. These points will

be mentioned in the hardware and software consider-

ation sections

As the complexity of USB data protocol does not permit

comprehensive USB operation information to be pro-

vided in the related datasheets, the reader should there-

fore consult other external information for a detailed

USB understanding.

Multi-chip Hardware Considerations

As these single-package multi-chip devices are com-

posed of an individual MCU and SPI to USB chip, using

them together requires the user to take care of some

special points.

· Absolute Maximum Ratings

The Absolute Maximum Ratings for the two individual

chips must be checked for discrepancies and the nec-

essary care taken in device handling and usage.

· Power Supply

Examination of the block diagram will reveal that the

SPI to USB chip Ground pin, VSSU, has no internal

connection to the MCU Ground pin, VSS. For this rea-

son these two pins must be connected externally. With

the exception of the HT66FB60 device, the SPI to

USB chip power supply pin, VDDU, is internally con-

nected to the MCU power supply pin, VDD. For the

HT66FB60 device, the SPI to USB chip power supply

pin and the MCU power supply pin should be con-

nected together externally.

To calculate the power consumption for the devices,

the total operating current is the sum of the operating

current for the MCU specified in the MCU datasheet

and the operating current for the SPI to USB chip

listed in its datasheet. Similarly, the standby current is

the sum of the two individual chip standby currents.

· Power Down and Wake up

The MCU and SPI to USB chip are powered down in-

dependently of each other. The method of powering

down the MCU is covered in the relevant MCU

datasheet. The SPI to USB chip must be powered

down before the MCU is powered down.

After the device is powered down, it could be also

woken up by the SPI to USB chip interrupt except by

wake-up sources mentioned in the MCU datasheet.

When a USB interrupt occurs on the INT line, it will

wake up the MCU if the MCU has entered a power

down mode. After the MCU is woken up, the applica-

tion program must set the corresponding control bits

to make the device function normally.

· Interrupts

When a USB interrupt occurs, a low pulse will be gen-

erated on the INT line and sent to the peripheral inter-

rupt line PINT in the MCU to get the attention of the

microcontroller. When the USB interrupt caused by

one of the USB interrupt generation sources occurs, if

the corresponding interrupt control in the host MCU is

enabled and the stack is not full, the program will jump

to the corresponding interrupt vector where it can be

serviced before returning to the main program.

For a USB interrupt to be serviced, in addition to the

bits for the corresponding interrupt enable control in

the SPI to USB chip being set, the global interrupt en-

able control and the related interrupt enable control

bits in the host MCU must also be set. If these bits are

not set, then the interrupt signal will only be a wake-up

source and no interrupt will be serviced.

· Unbonded MCU pins

Examination of the relevant MCU datasheet will re-

veal that not all of the MCU I/O port lines are bonded

out to external pins. As a result special attention re-

garding initialisation procedures should be paid to

these port lines. If the pins are pin-shared with the an-

alog input pins, they will be setup as analog inputs and

the corresponding analog circuits will be disabled af-

ter a reset. When these pins are set as analog input

pins and the relevant analog circuits are disabled,

they will not consume any power even if the input pin

conditions are not kept as either high or low logic lev-

els. However, if the pins are not pin-shared with ana-

log input pins, they will be setup as input states

without pull high resistors after a reset. Users should

therefore ensure that these pins are setup in input

states with pull high resistors or in output states with

either a high or low levels to avoid additional power

consumption resulting from floating input pins.

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