Craft Port TM Tiny RS-232 Transceiver for Portable Applications ADM101E

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1 a FEATURES 6 kbit/s Transmission Rate Single V Power Supply Compatible with RS-3 Input/Output Levels.1 F Charge Pump Capacitors One Driver and One Receiver On-Board DC-DC Converter. V Output Swing with V Supply Low Power BiCMOS: A I CC Ultralow Power (1 A) Shutdown Mode 1-Lead SOIC Package APPLICATIONS Mobile Telephones Palmtop Computers PDAs Portable Instrumentation GPS Receivers Craft Port TM Tiny RS-3 Transceiver for Portable Applications ADM11E.1 F FUNCTIONAL BLOCK DIAGRAM V CC 1 V TO V 1 VOLTAGE C1 C1 INVERTER 9 V T IN 3.1 F.1 F ADM11E T1 8 7 SD T OUT R OUT R1 6 R IN V GENERAL DESCRIPTION The ADM11E is a single channel RS-3 driver and receiver in the Analog Devices Craft Port series, designed to operate from a single, V supply. A highly efficient charge-pump voltage inverter generates an on-chip V supply, which eliminates the need for a negative power supply for the driver and permits RS-3 compatible output levels to be developed using charge pump capacitors as small as.1 µf. A shutdown input disables the charge pump and puts the device into a low power shutdown mode, in which the current consumption is typically less than 1 µa. The transmitter is disabled during shutdown but the receiver remains functional. An epitaxial BiCMOS construction minimizes power consumption to 3 mw and also guards against latch-up. Overvoltage protection is provided allowing the receiver inputs to withstand continuous voltages in excess of ± 3 V. In addition, all I-O pins have ESD protection to levels greater than 1 kv. The ADM11E is available in a 1-lead µsoic package, which makes it ideal for serial communications in small, portable applications such as palmtop computers and mobile telephones, where a full, RS-3 serial interface is not required, but compact size and low power drain are paramount. Craft Port is a trademark of Analog Devices, Inc. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 916, Norwood, MA 6-916, U.S.A. Tel: 781/39-7 World Wide Web Site: Fax: 781/ Analog Devices, Inc., 1

2 ADM11E SPECIFICATIONS (V CC = V 1%, C1 = C =.1 F. All specifications T MIN to T MAX unless otherwise noted.) Parameter Min Typ Max Unit Test Conditions/Comments Output Voltage Swing ± 3. ±. V V CC = V ±%, T OUT Loaded with 3 kω to ± 3. ±. V V CC = V ±1%, T OUT Loaded with 3 kω to V CC Power Supply Current (Unloaded). 1 ma No Load, T IN = V CC or V CC Power Supply Current (Loaded) 1.8. ma T OUT Loaded with 3 kω to V CC Power Supply Current (Shutdown) 1 µa SD Input = V CC Input Logic Threshold Low, V INL.8 V Input Logic Threshold High, V INH. V Input Leakage Current ± 1 µa RS-3 Input Voltage Range 1 1 V RS-3 Input Threshold Low.8. V RS-3 Input Threshold High..6 V RS-3 Input Hysteresis. V RS-3 Input Resistance 3 7 kω TTL/CMOS Output Voltage Low, V OL. V I OUT = 1.6 ma TTL/CMOS Output Voltage High, V OH 3. V I OUT = 1. ma Propagation Delay. µs RS-3 to TTL Instantaneous Slew Rate 1 V/µs C L = 1 pf, R L = 3 kω 7 kω, T A = C Transition Region Slew Rate 11 V/µs R L = 3 kω, C L = 1 pf Measured from 3 V to 3 V or Vice Versa Baud Rate 6 kb R L = 3 kω, C L = 1 nf Output Resistance 3 Ω V CC = V, V OUT = ± V RS-3 Output Short Circuit Current ± ± 6 ma NOTES 1 Sample tested to ensure compliance. Specifications subject to change without notice. ABSOLUTE MAXIMUM RATINGS* (T A = C unless otherwise noted) V CC V V V to 6 V Input Voltages Driver Input T IN V to (V CC,.3 V) Receiver Input R IN ± 3 V Output Voltages Driver Output T OUT (V CC,.3 V) to (V,.3 V) Receiver Output R OUT V to (V CC.3 V) Short Circuit Duration T OUT Continuous Power Dissipation RM-1 (Derate 1 mw/ C above 7 C) mw Thermal Impedance C/W Operating Temperature Range Industrial (A Version) C to 8 C Storage Temperature Range C to 1 C Lead Temperature Soldering Vapor Phase (6 sec) C Infrared (1 sec) C ESD Rating > V ESD Rating (I-O Pins) kv *This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. ORDERING GUIDE Temperature Package Package Model Range Description Option ADM11EARM C to 8 C µsoic RM-1

3 ADM11E PIN FUNCTION DESCRIPTIONS Pin No. Mnemonic Function 1 Ground Pin. Must be connected to V. C1 Negative Terminal of C1 (if C1 is Polarized Capacitor). 3 V Internally Generated Negative Supply Voltage. T IN Driver Input (3 V to V TTL/CMOS Logic Levels). R OUT Receiver Output (3 V to V TTL/CMOS Logic Levels). 6 R IN Receiver Input (EIA-3 Signal Levels). 7 T OUT Driver Output (EIA-3 Signal Levels). 8 SD Shutdown Input. Logic 1 on this input puts the ADM11E into low power shutdown mode. 9 C1 Positive Terminal of Charge Pump Capacitor (if C1 is Polarized Capacitor). 1 V CC Positive Power Supply, Nominally V. PIN CONFIGURATION 1 1 V CC C1 9 C1 ADM11E V 3 TOP VIEW 8 SD (Not to Scale) T IN 7 T OUT R OUT 6 R IN Typical Performance Characteristics 1 CHARGE PUMP VOLTAGE Volts 1 3 I DD ma CURRENT ma TPC 1. Charge Pump Voltage vs. Current LOAD CAPACITANCE pf TPC. I DD vs. Load 6 kbps 3

4 ADM11E T X O/P Volts T X HI T X LO SLEW RATE Volts/ s SERIES 1 SERIES 1 1 LOAD CAPACITANCE pf TPC 3. Transmitter Output Voltage vs. Load 6 kbps 1 3 DATA RATE kbps TPC. Slew Rate vs. Data Rate 6 6 T X HI 3 T X HI T X O/P HI & LO V CC Volts TPC. Tx Output Voltage vs. Supply T X LO 6 7 T X OUTPUT VOLTAGE 1 1 T X LO LOAD CURRENT ma TPC 6. Transmitter Output Voltage vs. Load Current

5 ADM11E GENERAL DESCRIPTION The ADM11E is an RS-3 compatible line driver/receiver in the Analog Devices Craft Port series, containing one driver (transmitter) and one receiver. It is ideal for serial communication in small portable devices such as mobile telephones, palmtop personal computers and personal digital assistants, where a full, RS-3 serial interface is not required, and only Tx and Rx lines are required for low speed communication between devices. The ADM11E operates from a single, V supply, and generates its own, on-chip, V power supply, thus removing the need for a negative power supply for the driver. CIRCUIT DESCRIPTION The internal circuitry consists of three main sections. These are: 1. A charge pump dc-to-dc converter.. V logic to EIA-3 driver. 3. EIA-3 to V logic receiver. Charge Pump DC-DC Converter The dc-dc converter generates a negative supply voltage from the V supply, thus removing the need for a separate V rail. It consists of an on-chip khz oscillator, switching matrix and two external capacitors, as shown in Figure 1. V CC INTERNAL OSCILLATOR S1 S C1 S3 S C V = V CC Figure 1. Charge Pump DC DC Converter When S1 and S are closed, S3 and S are open, and C1 charges to V CC. S1 and S are then opened, while S3 and S are closed to connect C1 across C, dumping charge into C. Since the positive terminal of C is at ground, a negative voltage will be built up on its negative terminal with each cycle of the oscillator. This voltage depends on the current drawn from C. If the current is small, the voltage will be close to V CC, but will fall as the current drawn increases. Charge Pump Capacitors And Supply Decoupling For proper operation of the charge pump, the capacitors should have an equivalent series resistance (ESR) less than 1 Ω. As the charge pump draws current pulses from V CC, the V CC decoupling capacitor should also have low ESR. The V CC decoupling capacitor and V reservoir capacitor should also have low ESR because they determine how effectively ESD pulses are clamped to V CC or V by the on-chip clamp diodes. Tantalum or monolithic ceramic capacitors are suitable for these components. If using tantalum capacitors, do not forget to observe polarity. Transmitter (Driver) Section The driver converts V logic input levels into RS-3 compatible output levels. With V CC = V and driving an EIA-3 load, the output voltage swing is typically ±. V. Receiver Section The receivers are inverting level-shifters that accept EIA-3 input levels and translate them into V logic output levels. The inputs have internal kω pull-down resistors to ground and are also protected against overvoltages of up to ± V. The guaranteed switching thresholds are.8 V minimum and.8 V maximum. An unconnected receiver input is pulled to V by the internal kω pull-down resistor. This, therefore, results in a Logic 1 output level for unconnected inputs or for inputs connected to. The receivers have Schmitt trigger input with a hysteresis level of. V. This ensures error-free reception for both noisy inputs and for inputs with slow transition times. SHUTDOWN INPUT The shutdown input allows the ADM11E to be put into an ultralow power mode where the dc-dc converter is switched off and the transmitter is disabled. The receiver remains active during shutdown. Logic at this input enables the ADM11E, while a Logic 1 at this input shuts down the ADM11E.

6 ADM11E OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 1-Lead SOIC (RM-1).1 (3.1).11 (.9).37 (.9).31 (.78) PIN 1.1 (3.1).11 (.9) (.).187 (.7) (.) BSC.1 (3.).11 (.8).3 (1.1) MAX.1 (.3) SEATING PLANE.6 (.1).6 (.1). (.).1 (3.).11 (.8) 6.9 (.3).8 (.7). (.13).16 (.) C3 /1 (rev. A) ADM11E Revision History Location Page Data sheet changed from REV. to. Changes made to Outline Dimensions (RM-1) PRINTED IN U.S.A. 6