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UCC5341
PRELIMINARY
IrDA 115.2kbps Receiver
FEATURES
* * * * * * * Supports IrDA standard to 115.2kbps Data Rates 3V to 5V Operation Wide Dynamic Receiver Range from 200nA to 50mA Typical IrDA Compliant I/O Very Low Quiescent Current In Active Mode (250A Typical) Ultra Low Quiescent Current In Sleep Mode (0.5A Typical) Compatible with IrDA Detector Diodes
DESCRIPTION
The UCC5341 IrDA (Infrared Data Association) Receiver supports the analog section of the IrDA standard. It has a limiting transresistance amplifier to detect a current signal from a PIN diode and drives RXX pulses to a UART. The amplifier is capable of input currents ranging from 200nA to greater than 50mA. The UCC5341 is bandpass limited to reduce interference from other IR sources. The UCC5341 also has very low current consumption in the active mode (250A typically), making it excellent for power sensitive applications. The output of the receiver is designed to drive CMOS and TTL levels, for direct interfacing to IrDA compliant UARTs and Super I/O devices. Internal resistors are provided for decoupling the detector diode supply, thus minimizing the number of external components required.
BLOCK DIAGRAM
UDG-97062-1
1/98
UCC5341
ABSOLUTE MAXIMUM RATINGS
AVDD, CAT, DVDD. . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V CAT, DET, DVDD, SLEEP, . . . . . . . . . . -0.3V to AVDD + 0.3V IRXX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA to 10 mA IDET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250mA Storage Temperature . . . . . . . . . . . . . . . . . . . -65C to +150C Junction Temperature . . . . . . . . . . . . . . . . . . . -55C to +150C Lead Temperature (Soldering, 10sec.) . . . . . . . . . . . . . +300C
ABSOLUTE MAXIMUM RATINGS
SOIC-8, DIL-8 (Top View) D, N Package
All voltages are with respect to respect to AGND. DGND must be connected to AGND. Currents are positive into, negative out of the specified terminal. Consult Packaging Section of the Databook for thermal limitations and considerations of packages.
ELECTRICAL CHARACTERISTICS: Unless otherwise specified, TA = 0C to 70C, AVDD = 3.0V to 5.5V, CAVDD = 100nF, CDVDD = 100nF, CCAT = 4.7F + 100nF, CRXX = 40pF, CDET < 56pF. All currents are positive into a specified pin. TA = TJ
PARAMETER Supply Current Section IDD IDD RDVDD RCAT Receiver Section Input Refered Noise (Note 1) 10 No Output Load, SLEEP 0.5V SLEEP AVDD - 0.5V AVDD to DVDD AVDD to CAT 1.0 10 250 0.5 2 20 350 3 3.0 32 A A k TEST CONDITION MI N TYP MAX UNITS
pA Hz
400 nA nA kHz MHz 8.0 s mV mV ns ns 400 400 200 150
Detection Threshold Signal to Noise Ratio Lower Band Limit Upper Band Limit Output Pulse Width RXX Output (VOL) RXX Output (VOH) RXX Rise Time RXX Fall Time
1.6s Input Pulse, 1s RXX 8s IDET = 200nA, (Note 1) (Note 1) (Note 1) IDET = 400nApk to 20mApk, 0 to 200ADC, 1.6s Input Pulse IRXX = 800A IRXX = -100A, DVDD - RXX From 10% to 90% of DVDD From 90% to 10% of DVDD 1.0
200 11.8 50 1 200 200 150 100
Note 1: Guaranteed by design. Not 100% tested in production.
PIN DESCRIPTIONS
AGND: Ground reference for analog circuits. Connect to circuit board ground plane. AVDD: Supply pin for analog circuits. Bypass to AGND with a 100nF or 1F ceramic capacitor. CAT: Filtered Supply for PIN diode cathode. Internally connected to AVDD through a 20 resistor. Bypass to AGND with a 4.7F capacitor plus a 100nF ceramic capacitor. DET: Input to receiver amplifier. Connect to PIN diode anode. Shield with AVDD and/or AGND from all other signals, especially RXX. DGND: Ground pin for digital circuits. Connect to circuit board ground plane. DVDD: Supply pin for digital circuits. Internally connected to AVDD through a 2k resistor. Bypass to DGND with a 100nF or 1F ceramic capacitor. RXX: Output of the detect amplifier and buffer. Connect to UART. Avoid coupling the RXX signed to DET. SLEEP: Sleep mode select pin. A logic high on SLEEP puts the chip into sleep mode, reducing IDD to 0.5A typical.
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UCC5341
APPLICATION INFORMATION
Ground Plane There are 2 ground connections shown on the application drawing, representing the sensitive analog ground and the `dirty' digital ground. These 2 points can simply be geographic groupings of connections to a ground plane. If a ground plane is not used, other provision to isolate the analog and digital ground currents should be provided. The use of a ground plane is strongly recommended. DET Considerations DET is flanked by AGND and CAT. This should be used to good advantage by fully enclosing the DET circuit board trace with AGND in order to shield leakage noise from DET. The DET circuit board trace length should be minimized. Since the PIN diode connected to DET is capacitive, noise coupling to the cathode of the diode will be coupled directly to DET. For this reason, the 100nF capacitor on CAT should be located physically close to the cathode of the PIN diode. There is natural parasitic coupling from RXX to DET. RXX should be routed to minimize the parasitic capacitive coupling from RXX to DET. Analog Power Supply Decoupling The UCC3541 has a highly sensitive amplifier section capable of detecting extremely low current levels (200nA typical). Achieving this sensitivity requires quiet analog power supply rails. A 100nF high frequency capacitor in close proximity to AVDD and AGND is required for quiet analog rails. Digital Power Supply DVDD is fed directly from AVDD through an internal 2k resistor. The DVDD bypass capacitor handles all transient current produced by the digital section of the chip. If more drive is required from RXX than the internal 2k resistor will allow, an external resistor can shunt it. This should always be accompanied by increasing the value of the decoupling capacitor on DVDD and AVDD. Economy Application The diagram of the economy application shows only one bypass capacitor. This application is suitable where maxi-
UDG-97153
Figure 1. Typical Application of the UCC5341
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UCC5341
APPLICATION INFORMATION (cont.)
UDG-97154
Figure 2. Economy Application of the UCC5341
UNITRODE CORPORATION 7 CONTINENTAL BLVD. * MERRIMACK, NH 03054 TEL. (603) 424-2410 * FAX (603) 424-3460
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Copyright (c) 1999, Texas Instruments Incorporated

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