Motorola MC13173FTB Datasheet

MOTOROLA ANALOG IC DEVICE DATA

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The MC13173 is a low power infrared integrated system (IRIS). It is a unique blend of a split IF wideband FM receiver and a specialized infrared LED transmitter. This device was designed to provide communications between portable computers via a half duplex infrared link at data rates up to 200 kbps.

The receiver includes a mixer, IF amplifier and limiter and data slicer. The IF amplifier is split to accommodate two low cost cascaded filters. The RSSI output is derived by summing the output of both IF sections.

The transmitter section includes a frequency synthesizer, FSK modulator , harmonic low pass filter and an IR LED driver.

• Transmitter Operates in Two Modes:

– On/Off Pulsing for Remote Control – FSK Modulation at 1.4 MHz for Data Communications

• Over 70 dB of RSSI Range

• Split IF for Improved Filtering and Extended RSSI Range

• Digitally controlled Via a Six Line Interface Bus

• Individual Circuit Blocks Can Be Powered Down When Not In Use for

Power Conservation

Device

Operating

Temperature Range

Package



SEMICONDUCTOR

TECHNICAL DATA

INFRARED

TRANSCEIVER

ORDERING INFORMATION

MC13173FTB TA = – 40° to +85°C TQFP–32

FTB SUFFIX

PLASTIC PACKAGE

CASE 873

(Thin QFP)

Order this document by MC13173/D

Simplified Block Diagram

This device contains 914 active transistors.

32 kHz Ma Tx 14 MHz

Data

IR LED

32 31 30 29 28 27 26 25

9 10111213141516 IF IF IF V Lim Lim Lim RSSI

Master

FSK

Mode Select

Harmonic

Driver

Data Slicer

Limiter

Mixer

Dec1 Dec2 Out

CC2

In Dec1 Dec2

12 M

RF In1

RF In2

Mixer

IF In

LED Driver

Data Out

Data

Demod

Quad Coil

Carrier

Ref PLL PLL Ref In Driver

Feedback

EE3

EE2

Slicer In

Detect

VCO/PLL

Modulator

LPF

Amplifier

Reg1

Reg2

EE1

Out

CC1

 Motorola, Inc. 1996 Rev 0

MC13173

MOTOROLA ANALOG IC DEVICE DATA

MAXIMUM RATINGS

Rating Symbol Value Unit

Power Supply Voltage VCC – V

6.0 Vdc

Junction Temperature T

150 °C

Storage Temperature T

stg

– 55 to +150 °C

NOTE: Devices should not be operated at or outside these values. The “Recommended Operating

Conditions” table provides for actual device operation.

RECOMMENDED OPERATING CONDITIONS

Characteristic Symbol Value Unit

Power Supply Voltage VCC – V

2.7 to 5.5 Vdc

Ambient Temperature Range T

– 40 to +85 °C

DC ELECTRICAL CHARACTERISTICS (T

= +25°C, VCC = 3.3 Vdc, f

REF

= 32.768 kHz. Measured using test circuit in Figure 1,

unless otherwise noted.)

Characteristic

Pin Symbol Min Typ Max Unit

Supply Current (See Table 2) Control Pin

Logic State

7, 12 I

Receive Mode Communications Mode A/V Mode Standby Mode

TR E 01 0 10 0 10 1 00 0

– – – –

6.5

4.75

1.5

<10

9.0

8.0 – –

Master PLL Charge Current 31 I

– ±25 – µA

DATA SLICER

Data Slicer Threshold Voltage 20 V

TH1

0.85 1.1 1.4 Vdc

Maximum Pull–Down Current 22 I

1.0 1.8 – mA

CARRIER DETECT

Carrier Detect Threshold Voltage 16 V

TH2

1.0 1.15 1.3 Vdc

Maximum Pull–Down Current 17 I

1.1 3.0 – mA

TRANSMITTER

Maximum Pull–Up Current 25 I

5.8 7.0 – mA

Maximum Pull–Down Current 25 I

– 150 700 µA

DC Output Voltage 24 V

– 200 – mV

Transmit PLL Charge Current 30 I

– ±25 – µA

AC ELECTRICAL CHARACTERISTICS (T

= +25°C, VCC = 3.3 Vdc, f

REF

= 32.768 kHz. Measured using test circuit in

Figure 1, unless otherwise noted.)

Characteristic

Pin Symbol Min Typ Max Unit

TRANSMITTER

Upper Sideband Frequency (Mark) 24 f

– 1.427 – MHz

Lower Sideband Frequency (Space) 24 f

– 1.317 – MHz

Upper and Lower Sideband Amplitude 24 V

40 54 70 mVrms

RECEIVER

Receiver Sensitivity – 12 dB SINAD 4, 19 V

SIN

– 5.0 – µV

MIXER

Mixer Conversion Gain 4, 5, 6 AV

(Mix)

– 23.5 – dB

Mixer Output Impedance 6 Z

– 330 – Ω

MC13173

MOTOROLA ANALOG IC DEVICE DATA

AC ELECTRICAL CHARACTERISTICS (continued) (T

= +25°C, VCC = 3.3 Vdc, f

REF

= 32.768 kHz. Measured using test circuit in

Figure 1, unless otherwise noted.)

Characteristic UnitMaxTypMinSymbolPin

IF AMPLIFIER

IF Amplifier Gain 8, 11 – – 54 – dB IF Amplifier RSSI Slope 16 – – 275 – nA/dB Input Impedance 8 Z

– 330 – Ω

Output Impedance 11 Z

– 330 – Ω RSSI Current Range 16 – – 20 – µA RSSI Dynamic Range 16 – – 70 – dB

LIMITING AMPLIFIER

Input Impedance 13 Z

– 330 – Ω Limiter RSSI Slope 16 – – 360 – nA/dB RSSI Current Range 16 – – 20 – µA RSSI Dynamic Range 16 – – 58 – dB

Figure 1. Test Circuit

10 k 127 k

100 k 100 k

10 k

– 1V

24.9 k

100 p

36 k

100 pF

MV209

10 k 10 k

200

ATTENLPF

330 50

MC13173

10 p

100 nF

10 nF

100 k

20 p

100 p200 k

10 k

2N2222A 10 k

100

100 n

10 k

6.81 k

150 p

1.0 n

CCVCC

0.1 F

0.001 Fµ0.1 H

– 1VV

0.001 F

0.1 F

0.3 H

100 p

0.001 F

0.1 H

0.1 F

33 F

0.1 F

1.0 H

100 n

1.0 n

100 n

0.1 F

ΩΩ

330

Ω

MC33202

32 25

916

CCVCC

0.1 F

1.0 n

MC13173

MOTOROLA ANALOG IC DEVICE DATA

CIRCUIT DESCRIPTION

General

The MC13173 infrared transceiver integrates a split IF wideband FM receiver and an IR LED transmitter into a single IC. The transmitter is comprised of an FSK modulator, harmonic low pass filter, and IR LED driver. The receiver consists of a mixer, IF amplifier and limiting IF, detector, and data slicer. It includes RSSI and carrier detect functions.

The transmitter is capable of two modes of operation. It was primarily designed for use in the Communications Mode, which enables point–to–point data links, such as the communication from keyboard to computer, or for the

exchange of data between portable computers. In this mode it is capable of 200 kbps half duplex FSK operation.

The transmitter can also operate in an “A/V” Mode, which

pulses the LED on and off with no carrier. (See Figure 11).

Digital Interface Bus

The MC13173 is controlled via a six line 3.3 V digital interface bus. That includes three control pins, data in and out pins, and a carrier detect pin. Listed below is a brief description of each pin and its function.

Table 1. Digital Interface Pin Descriptions

Pin Pin Name Symbol I/O Description

28 Transmit Enable T I High – Transmitter is enabled

Low – Transmitter is disabled

27 Data In DI I Data Input – 38.2 kbps

Communication Mode

3 Receive Enable R I High – Receiver is enabled

Low – Receiver is disabled 22 Data Out DO O Demodulated Output Signal 17 Carrier Detect CD O High – Carrier is present

Low – Carrier is not present 26 Transmit Modulation Enable E I High – Transmitter is in A/V Mode

Low – Transmitter is in

Communications Mode

This transceiver was designed for use in battery powered, hand–held consumer products. To minimize power consumption, the digital interface enables individual system

blocks to be powered down while not in use. The following diagram shows the mode of the IC and the power state of each circuit block for a given set of control levels.

Table 2. Power State Table

Control

Pins*

Circuit Block Power States

(See Figures 2 and 3)

T R E

Mode

Master

VCO

FSK

Modulator

Receiver

LED

Driver

Supply

Current

(Typical) 0 0 0 OFF Off Of f Off Off 10 nA 0 0 1 OFF Off Of f Off Off 70 µA 0 1 X Receive On Off On Off 6.5 mA 1 1 1 Receive On Off On On 7.5 mA 1 1 0 Transmit – Comm Mode On On On On 9.0 mA 1 0 0 Transmit – Comm Mode On On Off On 4.75 mA 1 0 1 Transmit – A/V Mode Of f Off Of f On 1.5 mA

* With Data In Pin Low

MC13173

MOTOROLA ANALOG IC DEVICE DATA

Master VCO/PLL

The master VCO provides the reference frequency for the FSK modulator and the LO frequency for the receiver downconverter. With a 32.768 kHz input frequency to the master VCO on Pin 1, the LO frequency for the receiver will be at 12.075 MHz. The reference frequency for the FSK modulator will be at approximately 1.1 MHz. The master VCO and FSK modulator are not used when the transmitter is used in A/V mode, and both are powered down.

Receiver Description

The single conversion receiver portion of the MC13173 is low power and wideband, and incorporates a split IF. This section includes a mixer, IF amplifier, limiting IF, quadrature detector and data slicer.

Mixer

The mixer is a double balanced four quadrant multiplier. It can be driven either differentially or single–ended by connecting the unused input to the positive supply rail.

The buffered output is internally loaded for an output impedance of 330 Ω for use with a standard ceramic filter.

IF Amplifier

The first IF amplifier section is composed of three differential stages with the second and third stages contributing to the RSSI. This section has internal DC feedback and external input decoupling for improved symmetry and stability. The total gain of the IF amplifier block is approximately 40 dB. The fixed internal input impedance is 330 Ω for use with a 10.7 MHz ceramic filter . The output of the IF amplifier is buffered and the impedance is 330 Ω .

Limiter

The limiter section is similar to the IF amplifier section, except that four stages are used with the last three contributing to the RSSI. This IF limiting amplifier section drives the quadrature detector internally.

RSSI/Carrier Detect

The received signal strength indicator (RSSI) outputs a current proportional to the log of the received signal amplitude. The RSSI current output is derived by summing the currents from the IF and limiting amplifier stages. An external resistor sets the output voltage range.

The carrier detect threshold is set at approximately

1.2 Vdc. When the RSSI level exceeds that threshold, the

carrier detect output will go high. A large resistor may be added externally between the comparator output and the positive input for hysteresis.

Quadrature Detector

The demodulator is a conventional quadrature type with an external LC tank driven through an internal 5 pF capacitor. The output is buffered to give an output impedance of less than 1.0 kΩ at an average DC level of around 1.1 V.

Data Slicer

The data slicer is designed to square up the data signal. It is self centering at about 1.1 V , and clips at about 0.75 V and

1.45 V . There is a short time constant for large peak–to–peak voltage swings or when there is a change in DC level at the detector output. The time constant is longer for small signals or for continuous bits of the same polarity which drift close to the threshold voltage.

Transmission Description

The MC13173 uses a dual modulus PLL to frequency shift key (FSK) modulate the baseband digital input signal, producing the necessary logic high and low frequencies for transmission. The transmit frequency for a logic high is

1.427 MHz, and the frequency for a low is 1.317 MHz with a

32.768 kHz reference frequency.

FSK Modulator

In the communications mode, the FSK modulator uses the reference frequency from the Master VCO to produce the two frequencies required for a logic high and a logic low. In the A/V mode, the FSK modulator is not used and is powered down.

LED Driver Stage

A low pass filter following the FSK modulator removes the undesired harmonic frequencies from the square–wave output of the divider circuits in PLLs. The resulting sinusoidal waveforms are fed into a unity gain difference amplifier, which drives the base of an external transistor, modulating the IR LED.

In A/V mode, the data is input directly into the inverting input of the op amp, and the low pass filter is not used.

MC13173

MOTOROLA ANALOG IC DEVICE DATA

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