Cirrus Logic CS8130-CS Datasheet

Semiconductor Corporation

Multi-Standard Infrared Transceiver

CS8130

Features

Adds IR port to standard UART

••

IrDA, HPSIR, ASK (CW) & TV remote

••

compatible 1200bps to 115kbps data rate

••

Programmable Tx LED power

••

Programmable Rx threshold level

••

Power down modes

••

Direct, no modulation, mode

••

Tiny 5x7mm 20 pin SSOP package

••

+2.7V to +5.5V supp ly

••

+Supply

General Description

The CS8130 is an infrared transceiver integrated circuit. The receive channel includes on-chip high gain PIN diode amplifier, IrDA, HPSIR, ASK & TV remote compatible decoder, and data pulse stretcher. The transmit path includes IrDA, HPSIR, ASK & TV remote compatible encoder, and LED driver. The computer data port is standard UART TxD and RxD compatible, and operates from 1200 to 115200 baud.

External PIN diode and transmit LED are required. A control mode is provided to allow easy UART programming of different modes.

The CS8130 operates from power supplies of +2.7V to +5.5V.

Ordering Information:

CS8130-CS 0° to 70°C 20-pin SSOP CDB8130 Evaluation kit

+Supply

PINA

PINC

+Supply

LED1C

LED2C

PIN Diode

Preamplifier

LED

Driver 1

LED Driver 2

TGND2 TGND1

Modulator

AGND

Preliminary Product Information

Crystal Semiconductor Corporation P.O. Box 17847, Austin, TX 78760 (512) 445-7222 FAX: (512) 445-7581

VA+

Threshold Detect/Decode

FIFO

Baud Rate Generator

EXTCLK

This document contains information for a new product. Crystal Semiconductor reserves the right to modify this product without notice.

XTALIN

VD+

Demodulator

Data/Control Decoder

XTALOUT

CLKFR

Semiconductor Corporation 1994

DGND

RESET

RXD

FORM/BSY

TXD

D/C

PWRDN

RxD

CTS

STANDARD

UART

TxD

DTR

JUN ’94

DS134PP2

CS8130

TRANSMITTER DRIVER CHARACTERISTICS (TA = 25 °C; All V+ = 3.0V, Digital Input Lev els: Logic 0 = 0V, Logic 1 = V+; unless otherwise specified)

Parameter Symbol Min Typ Max Units

Output capacitance (Note 1) 10 TBD pF Output rise time (10% to 90%) tr - 20 50 ns Output fall time (90% to 10%) tf - 20 50 ns Overshoot over final current - - 25 % On resistance - - 0.5 Off leakage current - - 20 Output current (each driver) (Note 2) - - 250 mA Output jitter relative a jitter free input clock - - 200 ns

Notes: 1. Typical LED junction capacitance is 20pF.

2. 50% duty cycle, max pulse width 165 µs (3/16 of (1/1200 bps + 5%)).

Ω

µA

RECEIVER CHARACTERISTICS (T

= 25 °C; All V+ = 3.0V, Digital Input Levels: Logic 0 = 0V, Logic 1 = V+;

unless otherwise specified)

Parameter Symbol Min Typ Max Units

Input capacitance (Note 3) - 10 T BD pF Input noise current - - 11 pA/rtHz Maximum signal input current from detector - - 2 mA Maximum DC input current (typically sunlight) - - 200 Input current detection thresholds RS4-0=00000:

(Programmable with a 5 bit value) RS4-0=00001: (Min, Max = Typical ±30%) RS4-0=00010: (Note 4) ↓

RS4-0=11110: RS4-0=11111:

Bandpass filter response High Pass -3dB:

Low Pass -3dB:

Receiver power up time With high (200µA) dc ambient

With normal (2µA) dc ambient

16.4

↓

169.5 175

7.8

15.6

23.4

↓

242.2 250

700

0.3

30.4

↓

314.9 325

µA nA

nA nA

" nA nA

kHz kHz

ms ms

Turn-around time, with receiver on continuously (Note 5) - 5 10 ms EMI rejection of system (0.5MHz to 100MHz). (Note 6) 3 - - V/m

Notes: 3. Typical PIN diode junction capacitance is 50pF.

4. The ±30% tolerance covers chip-to-chip variation. The temperature coefficient of the receiver threshold setting is low. Current detection thresholds are above the DC ambient condition. Settings of RS4-0 of less than 00010 are not practical because of noise.

5. Turn-around time is the time taken for the PIN diode receiver to recover from the IR energy from the transmitter. The remote end of the link must wait for this time after receiving data before transmitting a reply. This time may be reduced to <1 ms by good IR shielding from the transmit LED to the PIN diode.

6. This is a system specification. A metal shield over the P IN diode and CS8130 is recommended to ensure system compliance.

Specifications are subject to change without notice.

2 DS134PP2

CS8130

POWER SUPPLY SPECIFICATIONS (TA = 25°C; V+ = 3.0V, Digital Input Levels: Logic 0 = 0V, Logic 1 = V+, Note 7)

Parameter Symbol Min Typ Max Units

Power Supply Voltage 2.7 3.0 5.5 V Power Supply Current - All functions enabled (Note 8) - - 2.5 mA Power Supply Current - All functions disabled (Note 9) - - 1 Power Supply Current - Receiver only enabled (Note 8) - - 2.5 mA Power Supply Current - Transmit only enabled (Note 10) - - 0.5 mA Oscillator Power Supply Current low power mode:

normal power mode:

0.5

1.5

Data & State Retention Supply Voltage 2 - - V

Notes: 7. Power supply current specifications are with the supply at 3.0V. For approximate c onsumption at

+5.0V, multiply the above currents by 1.667.

8. Oscillator in low power mode, does not include LED current. Subtrac t oscillator current if using an external clock to run the CS8130.

9. Floating digital inputs will not cause the power s upply to increase beyond the specification.

10. Does not include LED current, does include os cillator current in low power mode.

RECOMMENDED OPERATING CONDITIONS (All voltages with respect to 0V)

µA

mA mA

Parameter Symbol Min Typ Max Units

Operating Ambient Temperature T

02570

Data and State Retention Temperature (In Power Down) -40 - 85

DIGITAL PIN CHARACTERISTICS (TA = 25°C, Supply = 3.0V)

Parameter Symbol Min Typ Max Units

High-level Input Voltage V Low-level Input Voltage V High-level Output Voltage at IO = -2.0mA V Low-level Output Voltage at IO = 2.0mA V

IH IL

2.0 - - V

--0.8V

VD-0.3 - - V

--0.3V Output Leakage Current in Hi-Z state 0.2 Input Leakage Current (Digital Inputs) - - 0.2 Output Capacitance C Input Capacitance C

OUT

-5-pF

°C °C

µA µA

DS134PP2 3

CS8130

ABSOLUTE MAXIMUM RATINGS (All v oltages with respect to 0V)

Parameter Symbol Min Max Units

Power Supplies -0.3 6.0 V Input Current Except Supply Pins & Driver P ins Input Voltage -0.3 VD+0.3 V Ambient temperature (Power Applied) -55 +125 Storage Temperature -65 +150

ESD using human body model (100pF with series 1.5kΩ)

2000 - V

Warning: Operation beyond these limits may result in permanent damage to the device.

Normal operation is not guaranteed at these extremes.

±10

°C °C

SWITCHING CHARACTERISTICS (T

= 25 °C; All V+ = 3.0V, Digital Input Levels: Logic 0 = 0V, Logic 1 = V+;

unless otherwise specified)

Parameter Symbol Min Typ Max Units

XTALIN frequencies CLKFR pin low: (Note 11) CLKFR pin high:

3.6864

1.8432

MHz

MHz XTALIN duty cycle 45 50 55 % Crystal Oscillator start up time - - 25 ms

Notes: 11. In normal oscillator mode, the crystal is internally loaded with 20 pF, which is the standard loading

at which the crystal frequency is tuned. In low power oscillator mode, the internal loading on the crystal is reduced to approximately 5pF. T he crystal frequency will therefore increase by about 0.03% in low power mode.

4 DS134PP2

CS8130

Ferrite

Ω

Bead

0.1 µF To LED

+3.0V supply

10 µF

TGND1, 2

0.1 µF

AGND

PINC

PIN Diode

PINA

+ Supply

47 µF

LED2

Use: LED1/R1 or:LED1/R1 & R2 or: LED1/R1 & LED2/R2

For 2 LED, +5V supply systems, connect 2 LEDs i n series. Use R1 & R2 to give programmable output level.

LED1

R1 TBD

R2 TBD

Ω

LED1C

Ω

LED2C

TGND1 TGND2 DGND CLKFR

VA+ VD+

FORM/BSY

CS8130

RXD

EXTCLK

XTALIN

XTALOUT

TXD

D/C

RESET

3.6864 MHz or 1.8432 MHz. Can also use an external clock at 3.6864 MHz or 1.8432 MHz

PWRDN

CLKFR low for 3. 686 4 MHz cl ock CLKFR high for 1.8432 MHz c l ock

RxD

CTS

UART

TxD

DTR

RTS

System Control

Figure 1. Recommended Connection Diagram

DS134PP2 5

CS8130

OVERVIEW

The CS8130 is an infrared transceiver I.C. The receive channel includes on-chip high gain PIN diode amplifier, IrDA, HP-SIR, 500 kHz Amplitude Shift Keying (ASK) & TV remote compatible decoder, and data pulse stretcher. The transmit path includes IrDA, HPSIR, 500 kHz ASK & TV remote compatible encoder, and LED drivers. The computer data port is standard UART TxD and RxD compatible, and operates from 1200 to 115200 baud. An on-chip baud rate generator is provided.

External PIN diode and transmit LED(s) are required. A control mode is provided to allow easy UART programming of different modes.

The CS8130 operates from power supplies of +2.7 V to +5.5 V. The device is supplied in a 20pin SSOP package

Serial Infrared (SIR) Physical Layer Link Specification, Version 1.0, April 27 1994). Figure 2 shows the format of Mode 1. A pulse of IR energy indicates a logic ’0’. No IR indicates a logic ’1’. The pulse can be from 3/16 of a bit

cell time at 115200 (~1.6 µs), to 3/16 of a bit cell time at 2400 bps (~78 µs). The width of the pulse may be fixed at 1.6µs for all baud rates, or

may scale with the baud rate. The initial baud rate for IrDA is 9600 bps, with a negotiated baud rate possibility of 2400 to 115200 bps.

Mode 2 500 kHz ASK

Figure 3 shows the infrared data format for Mode 2. This is a Carrier Wave (CW) type system, where the presence of a 500kHz carrier is treated as a ’0’, and absence of a carrier is treated as a ’1’. Normally used baud rates are 9600 bps, 19.2 kbps and 38.4 kbps.

FUNCTIONAL DESCRIPTION

The following pages describe the detailed operation of the CS8130.

IR Data Formats

The CS8130 supports three infrared data transmission formats: IrDA/HPSIR, 500kHz ASK and 38kHz ASK (TV Remote). There is also a direct access mode, which bypasses the CS8130 encoder and decoders, and gives direct access to the IR raw data. This mode is for situations where the encoding and/or decoding is done externally.

Modes may be set independently for transmit and receive, although this would be unusual.

Mode 1 IrDA/HP-SIR

The CS8130 is designed to allow easy realization of an IrDA compatible IR port (see IrDA

Mode 3 38 kHz ASK (TV remote mode)

Figure 4 shows the infrared data format for Mode 3, the TV remote control mode. This is similar to Mode 2, except that the modulation frequency is ~38kHz. The IR bit rate is approximately 2400 bps. Both modulation frequency and bit rate vary significantly for different manufacturer and model remote controls.

Mode 4 Direct Access Mode

In Mode 4, the IR transmission tracks directly what is present on the TXD pin. A logic ’1’ means that the LED is off, a logic ’0’ means that the LED is on. Care must be taken to ensure that the LED is not ’on’ continuously, otherwise the LED may be damaged.

In Mode 4, received IR is compared against the programmed threshold. The resulting logic output is routed directly to the RXD pin. A logic ’1’ means no IR is detected, a logic ’0’ means IR is being detected. If a IR carrier is being received,

6 DS134PP2

CS8130

TRANSMITTER

RECEIVER

A: 1/baud rate B: 3/16 of 1/115200 o C: 3/16 of 1/115200 t

TRANSMITTER

TXD

* LED Output

PIN Input

** RXD

r 3/16 of A (selectable)

o 3/16 of A

C * LED1C and LED2C go low to turn on LED.

** RXD output is delayed from the PIN diode input by A (1 bit).

Figure 2. Infra Red Data Format Mode 1 (IRDA/HPSIR)

TXD

LED Output

On Off

Light No Light

On Off

RECEIVER

A: 1/baud rate B: 1/527kHz C: 1/500kHz +/- 10%

TRANSMIT TER

RECEIVER

A: 1/2400 B: 1/38.4kHz C: 1/40kHz +/- 10%

PIN Input

RXD

Figure 3. Infra Red Data Format Mode 2 (500kHz ASK)

TXD Data *

LED Output

PIN Input

RXD Data *

These numbers are typical values. TV Remote Bit Rate and Modulation Frequency are programmable.

Light No Light

On Off

Light No Light

* The timing of data on the RXD and TXD pins is faster than shown here

Figure 4. Infra Red Data Format 3 (TV Remote, 38kHz ASK)

DS134PP2 7

CS8130

then the RXD pin will oscillate at the carrier frequency.

Transmit Path

Data for transmission is input to the CS8130 on the TXD pin. The selected modulation scheme is then applied to the data, and the resulting signals are used to drive the LED. There are 2 LED output pins: LED1C and LED2C. They are open drain outputs, which pull down to TGND or float. The LED is connected via resistors to both LED1C and LED2C. The current level flowing through the LED is determined by the external resistors. Normally, LED1C is used to drive the LED. If additional current is needed, (for example for TV remote operation), then the second driver may be enabled. The amount of ’boost’ current is determined by the external resistor connected to the LED2C pin.

For larger amounts of IR output, it may be preferable to use two LEDs, rather than drive a large current through one LED. For a +3V supply system using two LEDs, each one is connected, via a resistor, to each driver output. For a +5V supply system, 2 LEDS may be connected in series, and then routed to each driver via 2 resistors, one for each driver. This minimizes the power dissipation in the resistors.

Mode 1 Transmit Choices

In Mode 1 (IrDA), the pulse width may be fixed at 1.6 µs, or set to 3/16 of the bit period. Either

of these settings will meet the IrDA standard, but fixed 1.6 µs pulses will save power at lower

baud rates.

In addition, there is a choice which affects the output pulse jitter. The default state causes the CS8130 to look for the start bit on TXD. All subsequent LED transitions for that character are timed relative to the internal baud rate clock. Therefore there will be no jitter in the LED out-

put pulse timing. However, the CS8130 now has to be programmed with the desired number of bits per character, which for IrDA compliance, is

Alternatively, the CS8130 can generate output pulses based entirely on individual transitions on TXD, with no knowledge of which bit is the start bit. Thus a 1 to 0 transition will generate a pulse based on that transition edge. If TXD is low for multiple successive bits, then the CS8130 will generate pulses based on its internal clock. Therefore there is the possibility of jitter in the output pulses of N*271 ns. N can be 0, 1

2....., depending on the difference in frequency

between the UART baud rate clock and the CS8130 clock. Clearly, if the CS8130 and its associated UART are running from the same clock, the possibility of jitter is eliminated.

Mode 2 (ASK) Transmit Choices

The modulation frequency is determined by the modulator divider registers. For nominal 500 kHz, use a divide value of 6, which yields a modulation frequency of 527 kHz.

Mode 3 (TV Remote) Transmit Choices

During transmission of IR, the start and stop bits present in the incoming data from the UART are stripped off (see Figure 5). The remaining data bits are then sent out at ~2400 bps. Since there should be no gaps in the transmitted data, the input data is buffered in a 22-character location FIFO. Characters can be received on the TXD pin while the previous characters are being transmitted. To prevent overflow, a hardware handshake mechanism is provided. If the FIFO is one character away from being full, the FORM/BSY pin is brought high, indicating that the UART should not send any more data. Once another character has been transmitted, FORM/BSY pin is brought low, indicating to the UART that it is OK to send another character.

8 DS134PP2

CS8130

The modulation frequency is determined by the modulator divider registers. The transmit bit rate is determined by the TV Remote transmit bit rate divider. The UART to CS8130 baud rate must be set to at least 20% faster than the transmit bit rate.

Receive Path

A PIN diode is attached to the PINA and PINC pins. Compensation for the DC ambient light is applied to the photocurrent from the diode. The change in photocurrent from ambient is amplified and compared to a threshold value. If the photocurrent is greater than the set threshold, the output is set to ’light’. If the photocurrent is less than the set threshold, the output is set to ’no light’. The threshold current is programmable. This allows users to make the tradeoff between noise immunity and the reliable transmission distance of the link. The PIN diode amplifier has a bandpass filter characteristic, to limit the effects of IR interference. The resulting logic signal is further qualified, depending on the IR format selected.

An autodetect feature is provided. If autodetect mode is enabled, and transmit TV remote mode is disabled, the FORM/BSY output pin indicates

the format of incoming data. If high, then the incoming data is in IrDA/HPSIR format. If low, the data is in ASK format which matches the programmed modulation frequency.

Mode 1 (IrDA) Receive Choices

For Mode 1a, a logic circuit is set to only look for pulse widths of 1.6µs. For Mode 1b, a logic

circuit looks for pulses of 3/16 of the set baud rate bit period. For Mode 1c, a logic circuit

looks for pulse widths of ≥1.6 µs, but ≤3/16 of the set baud rate bit period.

Mode 2 (ASK) Receive Choices

For Mode 2, a logic circuit looks for sequences of ’light’ and ’no light’ which matches the expected 500kHz carrier. The modulator divider registers must be set to 6. The ASK receive timing sensitivity register should be set to 0, yielding a valid incoming frequency range of 461 kHz to 614 kHz.

The RXD data transitions will lag behind the infrared activity by 3 modulation cycles. This allows the modulation detect circuit time to verify the correct modulation frequency.

Start

Bit

TXD*

FORM/BSY

1/2400

LED OUTPUT

* TXD Baud rate can be set

from 4800 to 115200 bps

Figure 5. Mode 3 ( TV Remote ) Transmit D ata Form at

DS134PP2 9

Stop

Bit

001 0011000

ABC

OFF

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