General Transmitter Circuit

Configurations

Figure 3 shows several typical circuit configurations for a

HiSeC based RKE system transmitter Note that all circuits

require few external components beyond a battery and

transmitter stage IR and RF bit timing may be optimized

through the timer block settings in the EEPR0M array which

allows flexibility in selecting the smallest and least expen-

sive clock components in the chosen design range

The first two circuits are examples of RF transmitter applica-

tions with both RC and crystal (XTAL) oscillator clocks the

third circuit is an example of an IR transmitter application

Two circuits are configured for an LED Note that the LED

pin refers to a visual indicator LED and not the IR LED

which might be used in an IR transmitter circuit

The LEDSEL bit in the EEPROM array determines whether

the RFEN LED or CKOLED pins are dedicated to the LED

for a particular circuit configuration LED pin select options

are detailed in Table I

Design considerations for selecting and optimizing clock

component values are detailed in the Generator Clock De-

sign Parameters section

General Receiver Circuit

Configurations

The NM95HS0102 HiSeC Generator with the standard

customer algorithm is matched to a companion partthe

MM57HS HiSeC Decoder For applications requiring more

extensive receiver design and decoder programming a

COPS8xxxNM93Cx6 package is recommended A com-

plete discussion of receiver oonfigurations and considera-

tions can be found in the National Semiconductor Applica-

tion Note

How to Design and Program a HiSeC RKE Re-

ceiver using an 8-Bit Microcontroller

TLD12302 – 3

FIGURE 3 Typical Transmitter Circuit Configurations

TABLE I LED Pin Select Options

Clock

LEDSEL

RFEN LED

CKOLED

Function

RC

X

RFEN

LED

RF Mode with LED

XTAL

0

LED

CKO

RF Mode wo LED

XTAL

1

RFEN

CKO

IR mode with LED

Either the LED or RFEN outputs of the NM95HS0102 can be used to indicate device transmis-

sion The LED output is active during a pause whereas the RFEN output is active during frame

transmission

The IR Drive Current is 10 mA so an amplifier stage may be needed

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