HT95R43/HT95R44

Rev. 1.00

5

March 31, 2010

Functional Description

As these devices contain multiple internal chips, for a

detailed functional description, users must refer to the

relevant individual datasheets for both the MCU and the

CPT Detector. The following table shows which individ-

ual devices are inside each package.

Device

MCU

CPT Detector

HT95R43

HT95R33

HT9020B

HT95R44

HT95R34

HT9020B

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.

Multi-chip Hardware Considerations

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

posed of an individual MCU and CPT Detector chips,

using them together requires the user to take care of

some special points.

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.

Examination of the block diagram will reveal that the

CPT Detector ground and power supply pin, VSS4

and VDD4, are not internally connected to the MCU

ground and power supply pins, VSS and VDD. For this

reason these two pins must be connected externally.

When calculating the total current consumption of the

device, the internal DC specifications of the two inter-

nal chips must be consulted and the individual cur-

rents added together.

When calculating the total current consumption of the

device, the internal DC specifications of the two inter-

nal chips must be consulted and the individual cur-

rents added together.

Please note that if the MCU is powered down or

placed into a low power mode to conserve power, that

the CPT Detector will continue running and will con-

sume a certain amount of power. The CPT Detector

can of course be powered down by pulling its CPTEN

pin high.

Examination of the block diagram will reveal that the

CPT Detector pins, CPTEN, CPTX1, CPTX2,

CPTENV, CPTVREF, CPTSIN, VDD4, VSS4, have no

internal connection to the MCU pins. For this reason

these pins must be controlled and connected exter-

nally.

Multi-chip Programming Considerations

As there are no internal signal connections between the

two internal chips there are no real programming con-

siderations for these devices. It is only necessary to

realise that if the MCU is switched into any of its low

power modes or executes the HALT instruction by the

application program to reduce power consumption, that

the CPT Detector will continue operating and therefore

contribute to the overall power consumption. The CPT

Detector can only be powered-down manually using its

CPTEN pin.