19-1253; Rev 0; 8/97 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset The MAX3320 transceivers have a proprietary lowdropout transmitter output stage, enabling true RS-232 performance with a dual charge pump powered from a +3V to +5.5V supply. The device requires only four small 0.1µF external charge-pump capacitors, and is guaranteed to run at data rates of up to 250kbps. It comes in the space-saving 20-pin SSOP package. ________________________Applications Palmtop Computers Portable/Battery-Powered Equipment Hand-Held Equipment Peripherals __________________Pin Configuration TOP VIEW V+ 1 20 C1+ C2+ 2 19 VCC C2- 3 18 C1- T1IN 5 MAX3320 MAXxxx T2IN 6 ♦ 4µA Supply Current Achieved with AutoShutdown Plus ♦ Receivers Always Active ♦ Power-On Reset Always Active ♦ 4µA Low-Power Shutdown ♦ 250kbps Guaranteed Data Rate ______________Ordering Information PART* TEMP. RANGE MAX3320_CAP 0°C to +70°C 20 SSOP PIN-PACKAGE MAX3320_EAP -40°C to +85°C 20 SSOP SUFFIX RESET THRESHOLD (V) A 4.25 B 2.85 L 4.63 T 3.08 17 GND 16 T1OUT 15 T2OUT R1OUT 7 14 R1IN R2OUT 8 13 R2IN INVALID 9 ♦ Precise Monitoring of 5V and 3.3V PowerSupply Voltages: — 100ms (min) Power-On RESET Pulse Width — Power-Supply Transient Immunity — Guaranteed RESET Valid to VCC = 1V * This part offers a choice of reset threshold voltage. From the table below, select the suffix corresponding to the desired threshold and insert it into the blank to complete the part number. Printers V- 4 ____________________________Features Typical Operating Circuit appears at end of data sheet. 12 FORCEON RESET 10 11 FORCEOFF SSOP AutoShutdown Plus is a trademark of Maxim Integrated Products. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468. MAX3320A/B/L/T _______________General Description The MAX3320 combines a microprocessor (µP) supervisory circuit with an RS-232 transceiver. The power-on reset performs a single function: it asserts a reset signal whenever the VCC supply voltage declines below a preset threshold, staying asserted for at least 100ms after VCC rises above the reset threshold. The MAX3320 has an active-low RESET output, which is guaranteed to be in the correct state for VCC down to 1V. The reset comparator is designed to ignore fast transients on VCC. Reset thresholds suitable for operation with a variety of supply voltages are available. MAX3320A/B/L/T 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset ABSOLUTE MAXIMUM RATINGS Short-Circuit Duration VCC .............................................................................-0.3V to 6V T_OUT....................................................................Continuous V+ (Note 1) .................................................................-0.3V to 7V Continuous Power Dissipation (TA = +70°C) V- (Note 1)...................................................................0.3V to -7V SSOP (derate 8.00mW/°C above +70°C) ....................640mW V+ + |V-| (Note 1) ...................................................................13V Input Voltages Operating Temperature Ranges T_IN, FORCEOFF, FORCEON ................................-0.3V to 6V MAX3320_CAP ...................................................0°C to +70°C R_IN.................................................................................±25V MAX3320_EAP ................................................-40°C to +85°C Output Voltages Storage Temperature Range .............................-65°C to +160°C T_OUT ..........................................................................±13.2V Lead Temperature (soldering, 10sec) .............................+300°C R_OUT, INVALID, RESET.......................-0.3V to (VCC + 0.3V) Note 1: V+ and V- can have a magnitude of +7V (max), but their absolute difference cannot exceed +13V. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = 3V to 5.5V, C1–C4 = 0.1µF (tested at 3.3V ±10%), C1 = 0.047µF, C2–C4 = 0.33µF (tested at 5V ±10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER DC CHARACTERISTICS Power-Supply Current Shutdown Supply Current AutoShutdown Plus Supply Current CONDITIONS MIN TYP MAX UNITS No load, VCC = 3.3V or 5V, TA = +25°C 0.45 1.0 mA FORCEOFF = GND, TA = +25°C 4.0 10 µA All R_IN unconnected, FORCEON = GND, FORCEOFF = VCC, all T_IN = VCC or GND, TA = +25°C 4.0 10 µA 0.8 V LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low T_IN, FORCEON, FORCEOFF VCC = 3.3V 2.0 VCC = 5V 2.4 Input Logic Threshold High T_IN, FORCEON, FORCEOFF Input Leakage Current T_IN, FORCEON, FORCEOFF ±0.01 Input Hysteresis T_IN, FORCEON, FORCEOFF IOUT = 1.6mA 250 Output Voltage Low Output Voltage High IOUT = -1mA RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High ±1.0 VCC 0.6 VCC 0.1 -25 0.6 1.2 VCC = 5V 0.8 1.5 1.5 2.4 VCC = 5V 1.8 2.4 3 V V VCC = 3.3V TA = +25°C V V 25 VCC = 3.3V µA mV 0.4 Input Hysteresis Input Resistance V V 0.3 V 5 kΩ 7 INVALID OUTPUT Receiver Input Threshold to INVALID Output High Figure 3, positive threshold 2.7 Figure 3, negative threshold -2.7 Receiver Input Threshold to INVALID Output Low Figure 3 -0.3 INVALID Output Voltage Low IOUT = 1.6mA 2 _______________________________________________________________________________________ V 0.3 V 0.4 V 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset (VCC = 3V to 5.5V, C1–C4 = 0.1µF (tested at 3.3V ±10%), C1 = 0.047µF, C2–C4 = 0.33µF (tested at 5V ±10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS INVALID Output Voltage High IOUT = -1mA Receiver Positive or Negative Threshold to INVALID High Figure 3 0.1 µs Receiver Positive or Negative Threshold to INVALID Low Figure 3 90 µs 25 µs VCC - 0.6 V AUTOSHUTDOWN PLUS (FORCEON = GND, FORCEOFF = VCC) Receiver or Transmitter Edge to Transmitters Enabled Figure 5 Receiver or Transmitter Edge to Shutdown Figure 3 15 30 60 sec TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kΩ to ground ±5.0 ±5.4 Output Resistance VCC = V+ = V- = GND, VT_OUT = ±2V 300 10M Output Short-Circuit Current T_OUT = GND, T_IN = VCC or GND Output Leakage Current VT_OUT = ±12V, VCC = 0 to 5.5V, transmitters disabled ±35 V Ω ±60 mA ±25 µA RESET OUTPUT RESET Operating Voltage Range RESET Threshold RESET Output Voltage MAX3320_C 1.0 5.5 MAX3320_E 1.2 5.5 MAX3320A 4.00 4.25 4.50 MAX3320B 2.70 2.85 3.00 MAX3320L 4.50 4.63 4.75 MAX3320T 3.00 3.08 3.15 ISINK = 1.2mA, VCC = reset threshold, MAX3320B/T 0.3 ISINK = 3.2mA, VCC = reset threshold, MAX3320A/L 0.4 ISINK = 50µA, VCC > 1V, MAX3320_C 0.3 ISINK = 100µA, VCC > 1.2V, MAX3320_E 0.4 V V V _______________________________________________________________________________________ 3 MAX3320A/B/L/T ELECTRICAL CHARACTERISTICS (continued) TIMING CHARACTERISTICS (VCC = 3V to 5.5V, C1–C4 = 0.1µF, C1–C4 = 0.1µF (for 3.3V ±10%), C1 = 0.047µF, C2–C4 = 0.33µF (tested at 5V ±10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) Maximum Data Rate PARAMETER CONDITIONS RL = 3kΩ, CL = 1000pF, one transmitter switching Receiver Propagation Delay R_IN to R_OUT, CL = 150pF Transmitter Skew | tPHL - tPLH | | tPHL - tPLH | Receiver Skew MIN TYP 0.3 tPLH 0.3 100mV overdrive from reset threshold RESET Active Timeout Period VCC = reset threshold UNITS kbps tPHL VCC to RESET Delay MAX 250 CL = 150pF to VCC = 3.3V, RL = 3kΩ to 7kΩ, 1000pf measured from +3V to -3V or -3V to CL = 150pF to +3V, TA = +25°C 2500pf Transition-Region Slew Rate µs 100 ns 200 ns 6 30 V/µs 4 30 40 100 µs 280 ms __________________________________________Typical Operating Characteristics (VCC = 3.3V, 250kbps data rate, C1–C4 = 0.1µF, all transmitters loaded with 3kΩ. Typical values are at TA = +25°C, unless otherwise noted.) 0 -2.5 8 POSITIVE SLEW 6 4 ONE TRANSMITTER AT 250kbps ONE TRANSMITTER AT 15.6kbps LOAD = 3kΩ + CL 2 -5.0 VT_OUT0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 4 5000 ONE TRANSMITTER AT FULL DATA RATE INDICATED 40 35 ONE TRANSMITTER AT 1/16 DATA RATE INDICATED 30 250kbps 25 20 120kbps 15 10 20kbps 5 0 -7.5 MAX3320 TOC03 NEGATIVE SLEW SUPPLY CURRENT (mA) 2.5 SLEW RATE (V/us) ONE TRANSMITTER AT 250kbps ONE TRANSMITTER AT 15.6kbps LOAD = 3kΩ + CL 10 45 MAX3320 TOC02 VT_OUT+ 5.0 12 MAX3320 TOC01 7.5 SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA SLEW RATE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE OUTPUT VOLTAGE (V) MAX3320A/B/L/T 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset 0 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5000 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset (VCC = 3.3V, 250kbps data rate, C1–C4 = 0.1µF, all transmitters loaded with 3kΩ. Typical values are at TA = +25°C, unless otherwise noted.) NORMALIZED POWER-UP RESET DELAY vs. TEMPERATURE MAXIMUM TRANSIENT DURATION vs. RESET COMPARATOR OVERDRIVE SHUTDOWN MODE 200 150 100 NOT IN SHUTDOWN MODE 50 1.030 POWER-UP RESET DELAY 250 MAX3320 TOC06 1.040 MAX3320toc05 MAXIMUM TRANSIENT DURATION (µs) 300 1.020 1.010 1.000 0.990 0.980 0.970 CBYPASS = 0.1µF 0 10 0.960 100 -40 1000 -20 0 20 40 60 80 TEMPERATURE (°C) RESET COMPARATOR OVERDRIVE (mV) ______________________________________________________________Pin Description PIN NAME FUNCTION 1 V+ 2 C2+ Positive terminal of inverting charge-pump capacitor 3 C2- Negative terminal of inverting charge-pump capacitor 4 V- 5, 6 T_IN 7, 8 R_OUT TTL/CMOS Receiver Outputs (R1OUT and R2OUT) 9 INVALID Output of the Valid Signal Detector. Asserts when no valid RS-232 levels are present on any of the receiver inputs for 90µs. 10 RESET 11 FORCEOFF Force-Off Input. Drive FORCEOFF low to shut down transmitters and on-board power supply. This overrides AutoShutdown Plus and FORCEON (Table 1). 12 FORCEON Force-On Input. Drive FORCEON high to override AutoShutdown Plus, keeping transmitters on (FORCEOFF must be high) (Table 1). 13, 14 R_IN 15, 16 T_OUT 17 GND 18 C1- Negative terminal of voltage-doubler charge-pump capacitor 19 VCC +3V to +5.5V Supply Voltage 20 C1+ Positive terminal of voltage-doubler charge-pump capacitor 5.5V generated by the charge pump -5.5V generated by the charge pump TTL/CMOS Transmitter Inputs (T1IN and T2IN) RESET Output. RESET remains low while VCC is below the reset threshold, and for 280ms (max) after VCC rises above the reset threshold. RS-232 Receiver Inputs (R2IN and R1IN) RS-232 Transmitter Outputs (T2OUT and T1OUT) Ground _______________________________________________________________________________________ 5 MAX3320A/B/L/T ____________________________Typical Operating Characteristics (continued) MAX3320A/B/L/T 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset Table 1. MAX3320 Output Control Truth Table FORCEON FORCEOFF AUTOSHUTDOWN PLUS* OPERATION STATUS T_OUT R_OUT X 0 X Shutdown (forced off) High-Z Active 1 1 X Normal operation (forced on) Active Active 0 1 <30sec* Normal operation (AutoShutdown Plus) Active Active 0 1 >30sec* Shutdown (AutoShutdown Plus) High-Z Active X = Don’t Care *Time since last receiver or transmitter input activity ______________ Detailed Description Dual Charge-Pump Voltage Converter The MAX3320’s internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5V (doubling charge pump) and -5.5V (inverting charge pump) while V CC remains in the 3V to 5.5V range. The charge pumps operate in discontinuous mode; they are enabled if the output voltages are less than 5.5V, and disabled if output voltages exceed 5.5V. Each charge pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies. POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER Laplink is a trademark of Traveling Software. 6 FORCEON INVALID MAX3320 T1 T2 I/O CHIP WITH UART RS-232 Transmitters The transmitters are inverting level translators that convert CMOS-logic levels to 5V EIA/TIA-232 levels. The MAX3320 transmitters guarantee a 250kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLink™). Transmitters can be paralleled to drive multiple receivers. Figure 1 shows a complete system connection. When FORCEOFF is driven to ground, the transmitter’s outputs become high impedance. When the AutoShutdown Plus circuitry senses that all receiver and transmitter inputs are inactive for more than 30sec, the transmitters turn off and the outputs go into a highimpedance state, but the receivers remain active. When the power is off or the MAX3320 is shut down, outputs may be driven up to ±12V. The transmitter inputs do not have pull-up resistors. Connect unused inputs to GND or VCC. FORCEOFF RS-232 R1 R2 CPU Figure 1. Interface Under Control of PMU RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels. All receivers have inverting outputs and are active in shutdown FORCEOFF (Table 1). AutoShutdown Plus Mode Maxim’s AutoShutdown Plus feature, which operates when FORCEOFF is high and FORCEON is low, achieves a 4µA supply current. When the MAX3320 senses no valid signal levels on all receiver and transmitter inputs for 30sec, the on-board power supply and drivers shut off, _______________________________________________________________________________________ 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset Tables 1 and 2 and Figure 2 summarize the MAX3320’s operating modes. FORCEON and FORCEOFF override the automatic circuitry and force the transceiver into its normal operating state or into its low-power standby state. When neither control is asserted, the IC enters AutoShutdown Plus mode and selects between these states automatically, based on the last receiver or transmitter input edge received. When shut down, the device’s charge pumps turn off, V+ decays to VCC , V- decays to ground, and the transmitter outputs turn off (high impedance). The time required to exit shutdown is typically 25µs (Figure 3a). Software-Controlled Shutdown If direct software control is desired, use INVALID to indicate DTR or Ring Indicator signal. Connect FORCEOFF and FORCEON together to bypass the AutoShutdown Plus feature so the line acts like a SHDN input. +0.3V R_IN 90µs TIMER R -0.3V INVALID INVALID ASSERTED IF BOTH RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 90µs. Figure 2a. INVALID Functional Diagram, INVALID Low +2.7V R_IN 90µs TIMER R -2.7V INVALID INVALID DEASSERTED IF EITHER RECEIVER INPUT HAS BEEN BETWEEN +2.7V AND -2.7V FOR LESS THAN 90µs. Figure 2b. INVALID Functional Diagram, INVALID High T_IN EDGE DETECT FORCEOFF S 30sec TIMER Power-On Reset In addition to issuing a reset to the microprocessor (µP) during power-up, power-down, and brownout conditions, the MAX3320 is relatively immune to shortduration, negative-going V CC transitions (glitches). Typically, a VCC transient that goes 100mV below the reset threshold and lasts 20µs or less does not cause a reset pulse (see Typical Operating Characteristics). Additional bypass capacitance mounted as close as possible to the VCC pin provides additional transient immunity. MAX3320 MAX3320A/B/L/T reducing supply current to 4µA. This occurs if the RS-232 cable is disconnected or the connected peripheral transmitters turn off. The system turns on again when a valid transition occurs at any RS-232 receiver or transmitter input. As a result, the system saves power without changes to the existing BIOS or operating system. The INVALID output is high when the receivers are active. Since INVALID indicates the receiver inputs’ condition, it can be used in any mode (Figure 2). R_IN EDGE DETECT AUTOSHDN R FORCEON Figure 2c. AutoShutdown Plus Logic FORCEOFF POWERDOWN* FORCEON Table 2. INVALID Truth Table AUTOSHDN RS-232 SIGNAL PRESENT AT RECEIVER INPUT INVALID OUTPUT Yes H No L * POWERDOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES. Figure 2d. Power-Down Logic _______________________________________________________________________________________ 7 MAX3320A/B/L/T 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset INVALID REGION * RECEIVER INPUTS VOLTAGE ** TRANSMITTER INPUTS VOLTAGE TRANSMITTER OUTPUTS VOLTAGE INVALID OUTPUT VCC 0 tAUTOSHDN INVL tAUTOSHDN tWU tWU V+ VCC 0 V* ALL RECEIVER/TRANSMITTER INPUTS INACTIVE ** ANY ONE RECEIVER/TRANSMITTER INPUT BECOMES ACTIVE FORCEON = GND, FORCEOFF = VCC Figure 3a. AutoShutdown Plus and INVALID Timing Diagram INVALID HIGH RECEIVER INPUT LEVELS 2.7V INDETERMINATE 0.3V 0V INVALID LOW -0.3V INDETERMINATE -2.7V INVALID HIGH Figure 3b. Receiver Positive/Negative Thresholds for INVALID __________Applications Information Ensuring a Valid Reset Output Down to VCC = 0V When VCC falls below 1V, RESET no longer sinks current: it becomes an open circuit. Therefore, highimpedance CMOS logic inputs connected to RESET 8 can drift to undefined voltages. This presents no problem in most applications, since most µPs and other circuitry is inoperative with V CC below 1V. However, in applications where RESET must be valid down to 0V, add a pull-down resistor to ground, holding RESET low (Figure 4). R1’s value is not critical; 100kΩ is large enough not to load RESET, and small enough to pull it to ground. Capacitor Selection The capacitor type used for C1–C4 is not critical for proper operation; use either polarized or nonpolarized capacitors. The charge pump requires 0.1µF capacitors for 3.3V operation. For other supply voltages, refer to Table 3 for required capacitor values. Do not use values smaller than those listed in Table 3. Increasing the capacitor values (e.g., by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. C2, C3, and C4 can be increased without changing C1's value. However, do not increase C1 without also increasing the values of C2, C3, C4, and CBYPASS, to maintain the proper ratios (C1 to the other capacitors). _______________________________________________________________________________________ 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset MAX3320A/B/L/T FORCEON = FORCEOFF VCC 2V/div T2OUT MAX3320 VCC GND RESET 2V/div 100k T1OUT VCC = 3.3V C1 - C4 = 0.1µF Figure 4. Ensuring RESET Valid to VCC = 0V When using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperatures outside the 0°C to +70°C range. If in doubt, use capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-. Transmitter Outputs when Exiting Shutdown Figure 5 shows two transmitter outputs when exiting shutdown mode. As they become active, the two transmitter outputs go to opposite RS-232 levels (one transmitter input is high; the other is low). Each transmitter is loaded with 3kΩ in parallel with 2500pF. The transmitter outputs display no ringing or undesirable transients as they exit shutdown. Note that the transmitters are enabled only when the magnitude of V- exceeds approximately 3V. Figure 5. Transmitter Outputs when Exiting Shutdown or Powering Up VCC Interconnection with 3V and 5V Logic The MAX3320 can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 4 for more information on possible combinations of interconnections. VCC C1+ V+ C3* C1 C1C2+ MAX3320 VC4 C2 C2- T_ OUT T_ IN R_ IN R_ OUT High Data Rates The MAX3320 maintains the RS-232 ±5V minimum transmitter output voltage even at high data rates. Figure 6 shows a transmitter loop-back test circuit. Figure 7 shows a loop-back test result at 120kbps, and Figure 8 shows the same test at 250kbps. For Figure 7, both transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 8, a single transmitter was driven at 250kbps, and both transmitters were loaded with an RS-232 receiver in parallel with 1000pF. 5µs/div 5k FORCEON VCC FORCEOFF 1000pF GND *C3 CAN BE RETURNED TO VCC OR GND. Figure 6. Loop-Back Test Circuit Table 3. Required Minimum Capacitance Values VCC (V) C1 (µF) C2, C3, C4, CBYPASS 3 to 3.6 0.1 0.1 4.5 to 5.5 0.047 0.33 3 to 5.5 0.1 0.47 (µF) _______________________________________________________________________________________ 9 MAX3320A/B/L/T 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset 5V 0V T1IN 5V 0V T1IN 5V T1OUT R1IN 0V 5V T1OUT R1IN 0V -5V 5V 0V R1OUT -5V 5V 0V R1OUT 2µs/div 2µs/div VCC = 3.3V C1 - C4 = 0.1µF CLOAD = 1000pF VCC = 3.3V C1 - C4 = 0.1µF CLOAD = 1000pF Figure 7. Loop-Back Test Result at 120kbps Table 4. Logic-Family Compatibility with Various Supply Voltages SYSTEM POWER-SUPPLY VOLTAGE (V) VCC SUPPLY VOLTAGE (V) COMPATIBILITY 3.3 3.3 Compatible with all CMOS families 5 5 5 3.3 10 Figure 8. Loop-Back Test Result at 250kbps ___________________Chip Information TRANSISTOR COUNT: 1577 Compatible with all TTL and CMOS families Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS ______________________________________________________________________________________ 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset +3.3V VCC 0.1µF C1 0.1µF VCC C1+ V+ C3* 0.1µF C1- C2 0.1µF C2+ MAX3320 VC4 0.1µF C2VCC T1IN T1 T2IN T2 T1OUT T2OUT RS-232 OUTPUTS FORCEOFF FORCEON µP SYSTEM R1OUT AUTOSHUTDOWN PLUS R1IN R1 5k R2OUT RESET INPUT R2IN R2 5k RESET INVALID RS-232 INPUTS GND *C3 MAY BE RETURNED TO EITHER VCC OR GND. ______________________________________________________________________________________ 11 MAX3320A/B/L/T ___________________________________________________Typical Operating Circuit ________________________________________________________Package Information SSOP.EPS MAX3320A/B/L/T 3V to 5.5V, up to 250kbps True RS-232 Transceiver with 4µA AutoShutdown Plus and Power-On Reset Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.