LTC2801/LTC2802/ LTC2803/LTC2804 1.8V to 5.5V RS-232 Single and Dual Transceivers FEATURES DESCRIPTION n The LTC®2801/LTC2802/LTC2803/LTC2804 are single and dual RS-232 transceivers in narrow SSOP and chip-scale DFN packages. All operate over a supply range of 1.8V to 5.5V, which permits operation directly from two alkaline, NiCd or NiMH cells. An integrated DC-to-DC converter generates power supplies for driving RS-232 levels. A logic supply pin allows easy interfacing with different logic levels independent of the DC-DC supply. n n n n n n n n 1.8V to 5.5V Supply Voltage Single and Dual Transceivers High-Speed Operation 1Mbps for 250pF/3kΩ Load (LTC2802, LTC2804) 250kbps for 1nF/3kΩ Load 100kbps for 2.5nF/3kΩ TIA/EIA-232-F Load Low-Power 1μA Shutdown and 15μA ReceiversActive Modes No Damage or Latch-Up to ±10kV ESD on RS-232 Interface Logic Supply Pin for Easy Level-Shifting to UART or Microprocessor Low-Latency Output Enable Allows Line Sharing and Half-Duplex Operation True RS-232 Compliant Output Levels Small Footprint: LTC2801/LTC2802 4mm × 3mm DFN Package LTC2803/LTC2804 Narrow SSOP-16 and 5mm × 3mm DFN Packages APPLICATIONS n n n Battery-Powered Systems Computers and Consumer Electronics Diagnostic Ports L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. These parts are compatible with the TIA/EIA-232-F standard. Driver outputs are protected from overload and can be shorted to ground or up to ±15V without damage. To extend battery life, receivers can be kept active, operating at reduced speed, with only 15μA current. In shutdown mode, current is further reduced to 1μA. Line sharing and half-duplex operation are also supported. PRODUCT SELECTION GUIDE PART NUMBER DRIVERS RECEIVERS LTC2801 1 1 12-Lead DFN PACKAGE LTC2802 1 1 12-Lead DFN LTC2803 2 2 16-Lead DFN LTC2803-1 2 2 16-Lead Narrow SSOP LTC2804 2 2 16-Lead DFN LTC2804-1 2 2 16-Lead Narrow SSOP TYPICAL APPLICATION 1.8V TO 5.5V C4 1μF LTC2802 at 1.8V and 1Mbps L1 10μH SW VCC VL MODE TIN 5V/DIV TOUT TOUT TIN RIN ROUT GND 2V/DIV CAP PS OFF ON C1 220nF LTC2802 2V/DIV VEE VDD C2 1μF C3 1μF ROUT VCC = VL = 1.8V 400ns/DIV WRAPPING DATA TOUT LOAD = 250pF + RIN ROUT LOAD = 150pF 2801 TA01b 2801 TA01a 2801234fc 1 LTC2801/LTC2802/ LTC2803/LTC2804 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supplies VCC........................................................... –0.3V to 7V VL.......................................................... –0.3V to 6.7V Generated Supplies VDD ................................................ VCC –0.3V to 7.5V VEE ........................................................ 0.3V to –7.5V VDD – VEE ..............................................................14V SW .................................................. –0.3V to VDD + 0.3V CAP .................................................. +0.3V to VEE – 0.3V TIN, T1IN, T2IN, MODE ................................ –0.3V to 7V PS, ON/OFF .....................................–0.3V to (VL + 0.3V) RIN, R1IN, R2IN.......................................... –25V to 25V TOUT, T1OUT, T2OUT ................................. –15V to 15V ROUT, R1OUT, R2OUT ....................–0.3V to (VL + 0.3V) Operating Temperature LTC280XC ................................................ 0°C to 70°C LTC280XI .............................................–40°C to 85°C Storage Temperature Range...................–65°C to 125°C Lead Temperature (Soldering, 10 sec) GN Package ...................................................... 300°C PIN CONFIGURATION 1-Driver/1-Receiver 2-Driver/2-Receiver 2-Driver/2-Receiver TOP VIEW TOP VIEW TOP VIEW R1IN 1 16 R1OUT R2IN 2 15 R2OUT 14 T1IN 13 T2IN R1IN 1 16 R1OUT R2IN 2 15 R2OUT T1OUT 3 14 T1IN T2OUT 4 13 T2IN 12 VL VCC 5 12 VL RIN 1 12 ROUT TOUT 2 11 TIN T1OUT 3 VCC 3 10 VL T2OUT 4 VDD 4 9 MODE VCC 5 SW 5 8 PS VDD 6 11 MODE VDD 6 11 ON/OFF GND 6 7 CAP SW 7 10 PS SW 7 10 CAP GND 8 GND 8 9 13 VEE DE PACKAGE 12-LEAD (4mm s 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 43°C/W, θJC = 4.3°C/W (4 Layer) EXPOSED PAD (PIN 13) IS VEE, MUST BE SOLDERED TO PCB 17 VEE 9 CAP VEE DHC PACKAGE 16-LEAD (5mm s 3mm) PLASTIC DFN GN PACKAGE 16-LEAD (NARROW 0.150) PLASTIC SSOP TJMAX = 125°C, θJA = 44°C/W, θJC = 4.3°C/W (4 Layer) EXPOSED PAD (PIN 17) IS VEE, MUST BE SOLDERED TO PCB TJMAX = 125°C, θJA = 110°C/W, θJC = 40°C/W (4 Layer) ORDER INFORMATION LEAD FREE FINISH LTC2801CDE#PBF TAPE AND REEL LTC2801CDE#TRPBF PART MARKING* 2801 PACKAGE DESCRIPTION 12-Lead (4mm × 3mm) Plastic DFN TEMPERATURE RANGE 0°C to 70°C LTC2801IDE#PBF LTC2801IDE#TRPBF 2801 12-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LTC2802CDE#PBF LTC2802CDE#TRPBF 2802 12-Lead (4mm × 3mm) Plastic DFN 0°C to 70°C LTC2802IDE#PBF LTC2802IDE#TRPBF 2802 12-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LTC2803CDHC#PBF LTC2803CDHC#TRPBF 2803 16-Lead (5mm × 3mm) Plastic DFN 0°C to 70°C LTC2803IDHC#PBF LTC2803IDHC#TRPBF 2803 16-Lead (5mm × 3mm) Plastic DFN –40°C to 85°C LTC2804CDHC#PBF LTC2804CDHC#TRPBF 2804 16-Lead (5mm × 3mm) Plastic DFN 0°C to 70°C LTC2804IDHC#PBF LTC2804IDHC#TRPBF 2804 –40°C to 85°C 16-Lead (5mm × 3mm) Plastic DFN LTC2803CGN-1#PBF LTC2803CGN-1#TRPBF 28031 16-Lead (Narrow 0.150) Plastic SSOP 0°C to 70°C LTC2803IGN-1#PBF LTC2803IGN-1#TRPBF 2803I1 16-Lead (Narrow 0.150) Plastic SSOP –40°C to 85°C LTC2804CGN-1#PBF LTC2804CGN-1#TRPBF 28041 16-Lead (Narrow 0.150) Plastic SSOP 0°C to 70°C LTC2804IGN-1#PBF LTC2804IGN-1#TRPBF 2804I1 16-Lead (Narrow 0.150) Plastic SSOP –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 2801234fc 2 LTC2801/LTC2802/ LTC2803/LTC2804 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 1.8V to 5.5V, VL = 1.8V to 5.5V, Normal Mode. Typical values are given for VCC = VL = 3.3V and TA = 25°C, unless otherwise noted. SYMBOL PARAMETER CONDITIONS VCC Supply Current Outputs Unloaded Normal Mode (Note 3) Receivers Active Mode Shutdown Mode MIN TYP MAX UNITS l l 2.3 1 1 10 10 mA μA μA Outputs Unloaded Normal Mode (LTC2801, LTC2802) Normal Mode (LTC2803, LTC2804) Receivers Active Mode Shutdown Mode l l l l 0.08 0.15 15 1 0.15 0.30 30 10 mA mA μA μA RL = 3kΩ Low l –5 High l 5 Power Supplies ICC IL VL Supply Current Driver VOLD Output Voltage RL = 3kΩ –5.7 V VOHD Output Voltage VHYSD Logic Input Hysteresis 6.2 V 0.6 V IOSD Output Short Circuit Current VL = VCC = 5.5V; VTOUT = 0V l ±35 ±70 mA IPOLD Power-Off Output Leakage Current VL = VCC = VDD = VEE = 0V; VTOUT = ±2V l ±0.1 ±10 µA IOLD Output Leakage Current l Shutdown or Receivers Active or Drivers Disabled Modes, –15V ≤ VTOUT ≤ 15V ±0.1 ±10 µA VIR Input Thresholds Receivers Active Mode l 0.8 1.5 2.4 V VILR Input Thresholds Normal Mode, Input Low l 0.8 1.3 VIHR Input Thresholds Normal Mode, Input High l VHYSR Input Hysteresis Normal Mode l Receiver V 1.7 2.5 V 0.1 0.4 1.0 V 0.2 0.4 VOLR Output Voltage Output Low, IROUT = 1mA (Sinking) l VOHR Output Voltage Output High, IROUT = –1mA (Sourcing) l VL –0.4 VL –0.2 RIN Input Resistance –15V ≤ VRIN ≤ 15V l 3 5 7 kΩ IOSR Output Short Circuit Current VL = 5.5V; 0V ≤ VROUT ≤ VL l ±25 ±50 mA V V Logic IIN Logic Input Voltage Threshold l Logic Input Current l 0.4 0.67 • VL V ±1 μA Power Supply Generator VDD VEE Regulated VDD Output Voltage Regulated VEE Output Voltage Driver RL = 3kΩ (Note 3) LTC2801, LTC2802: VTIN = VL LTC2803, LTC2804: VT1IN = VL , VT2IN = 0V 7 V Driver RL = 3kΩ (Note 3) LTC2801, LTC2802: VTIN = VL LTC2803, LTC2804: VT1IN = VL , VT2IN = 0V – 6.3 V 2801234fc 3 LTC2801/LTC2802/ LTC2803/LTC2804 SWITCHING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VCC = 1.8V to 5.5V, VL = 1.8V to 5.5V, Normal Mode. Typical values are given for VCC = VL = 3.3V and TA = 25°C, unless otherwise noted. SYMBOL PARAMETER CONDITIONS Maximum Data Rate LTC2801, LTC2803 (Note 3) RL = 3kΩ, CL = 2.5nF RL = 3kΩ, CL = 1nF MIN TYP MAX UNITS l l 100 250 kbps kbps LTC2802, LTC2804 (Note 3) RL = 3kΩ, CL = 2.5nF RL = 3kΩ, CL = 1nF RL = 3kΩ, CL = 250pF l l l 100 250 1000 kbps kbps kbps LTC2801, LTC2803 (Figure 1) VCC = VL = 1.8V, RL = 3kΩ, CL = 2.5nF VCC = VL = 5.5V, RL = 3kΩ, CL = 50pF l l 4 LTC2802, LTC2804 (Figure 1) VCC = VL = 1.8V, RL = 3kΩ, CL = 2.5nF VCC = VL = 5.5V, RL = 3kΩ, CL = 50pF l l 4 RL = 3kΩ, CL = 50pF (Figure 2) LTC2801, LTC2803 LTC2802, LTC2804 l l Driver SR(D) tPHLD, tPLHD tSKEWD Driver Slew Rate Driver Propagation Delay Driver Skew RL = 3kΩ, CL = 50pF (Figure 2) LTC2801, LTC2803 LTC2802, LTC2804 1 0.2 30 V/μs V/μs 150 V/μs V/μs 2 0.5 μs μs ns ns 100 50 tPZHD, tPZLD Driver Output Enable Time PS = VL, MODE = ↑, RL = 3kΩ, CL = 50pF (Figure 4) l 0.6 2 μs tPHZD, tPLZD Driver Output Disable Time PS = VL, MODE = ↓, RL = 3kΩ, CL = 50pF (Figure 4) l 0.3 2 μs l 0.2 0.4 μs Receiver tPHLR, tPLHR Receiver Propagation Delay CL = 150pF (Figure 3) tSKEWR Receiver Skew CL = 150pF (Figure 3) tRR, tFR Receiver Rise or Fall Time CL = 150pF (Figure 3) l 60 200 ns tPZHR, tPZLR Shutdown to Receiver Output Enable PS = MODE = ↑ or ON/OFF = ↑, RL = 1kΩ, CL = 150pF (Figure 5) l 5 15 μs tPHZR, tPLZR Receiver Output Disable upon Shutdown PS = MODE = ↓ or ON/OFF = ↓, RL = 1kΩ, CL = 150pF (Figure 5) l 0.15 0.3 μs (Notes 3 and 4) l 0.2 2 ms 50 ns Power Supply Generator VDD/VEE Supply Rise Time Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All currents into pins are positive; all voltages are referenced to GND unless otherwise specified. Note 3: Guaranteed by other measured parameters and not tested directly. Note 4: Time from PS ↑ or ON/OFF ↑ until VDD ≥ 5V and VEE ≤ –5V. 2801234fc 4 LTC2801/LTC2802/ LTC2803/LTC2804 TEST CIRCUITS TOUT 0V RL TIN VL TIN CL tTHL 3V –3V TOUT SR(D) = TIN tr, tf ≤ 40ns tTLH 3V –3V 6V VOHD VOLD 2801F02 tTHL or tTLH Figure 1. Driver Slew Rate Measurement TOUT VL TIN 1/2 VL 0V RL TIN 1/2 VL CL tPHLD tPLHD VOHD 0V TOUT 0V VOLD tSKEWD = |tPHLD – tPLHD| 2801F02 TIN tr, tf ≤ 40ns Figure 2. Driver Timing Measurement ROUT RIN 3V 1.5V 1.5V –3V CL RIN tPHLR tPLHR VOHR ROUT 1/2 VL 1/2 VL tSKEWR = |tPHLR – tPLHR| VOLR 2801F03 RIN tr, tf ≤ 40ns Figure 3. Receiver Timing Measurement MODE VL 1/2 VL 1/2 VL 0V 0 OR VL tPZHD TOUT tPHZD 5V TOUT VOHD – 0.5V VOHD 0V MODE RL CL tPZLD TOUT tPLZD 0V –5V VOLD + 0.5V VOLD 2801F04 MODE tr, tf ≤ 40ns Figure 4. Driver Enable/Disable Times 2801234fc 5 LTC2801/LTC2802/ LTC2803/LTC2804 TEST CIRCUITS GND VL PS AND MODE RL VL 1/2 VL 1/2 VL 0V –3V OR 3V tPZHR ROUT ROUT tPHZR 1/2 VL V VOHR – 0.5V OHR 0V PS AND MODE CL tPZLR ROUT tPLZR VL VOLR + 0.5V VOLR 1/2 VL 2801F05 PS AND MODE tr, tf ≤ 40ns Figure 5. Receiver Enable/Disable Times TYPICAL PERFORMANCE CHARACTERISTICS LTC2803 at 1.8V and 250kbps TA = 25°C, VCC = VL = 3.3V unless otherwise noted. Drivers Disabled Mode Supply Current vs Supply Voltage LTC2804 at 1.8V and 1Mbps 3.0 T1IN 2.5 2V/DIV T1OUT T1OUT T2OUT R1OUT 2801 G01 100 ALL DRIVERS SWITCHING VCC = VL RL = 3k 250kbps CL = 1nF SUPPLY CURRENT (mA) 125kbps 30 20.8kbps LTC2804 LTC2803 1 2 3 4 5 SUPPLY VOLTAGE (V) 2801 G04 250kbps 250pF 40 250pF 125kbps 60 40 20.8kbps 20 VCC = VL = 1.8V LTC2804 RL = 3k LTC2803 ALL DRIVERS SWITCHING LTC2804 LTC2802 200 6 2801 G03 80 60 0 5 3 4 SUPPLY VOLTAGE (V) 100 1nF 0 6 2 Supply Current vs Load Capacitance (Dual Transceiver) 1nF 20 10 1 2801 G02 ALL DRIVERS SWITCHING VCC = VL = 1.8V RL = 3k 80 40 20 0 Supply Current vs Data Rate 60 50 0.5 VCC = VL = 1.8V 400ns/DIV WRAPPING DATA TOUT LOAD = 250pF + RIN ROUT LOAD = 150pF Supply Current vs Supply Voltage (Dual Transceiver) SUPPLY CURRENT (mA) R2OUT 2V/DIV SUPPLY CURRENT (mA) VCC = VL = 1.8V 2μs/DIV WRAPPING DATA TOUT LOAD = 1nF + RIN ROUT LOAD = 150pF 1.0 R1OUT R2OUT TA = –40°C 1.5 10V/DIV 2V/DIV TA = 25°C 2.0 T2OUT 10V/DIV 0 SUPPLY CURRENT (mA) 2V/DIV VCC = VL TA = 85°C T1IN 600 400 DATA RATE (kbps) 800 1000 2801 G05 0 1 3 2 4 LOAD CAPACITANCE (nF) 5 2801 G06 2801234fc 6 LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL PERFORMANCE CHARACTERISTICS Receiver Output Voltage vs Load Current Receiver Input Threshold vs Temperature VL = 5.5V VL = 3.3V VL = 1.8V INPUT HIGH 2.0 1.5 INPUT LOW 1.0 0.5 Receiver Output Duty Cycle 4 3 2 1 50 25 75 0 TEMPERATURE (°C) 100 0 125 1 2 3 4 5 6 LOAD CURRENT (mA) Driver Slew Rate vs Load Capacitance SHORT-CIRCUIT CURRENT (mA) SLEW RATE (V/μs) 60 50 40 30 20 10 0 1 2 4 3 LOAD CAPACITANCE (nF) RECEIVERS ALIVE MODE 60 5 NORMAL MODE 40 20 7 VL = 5.5V VL = 3.3V VL = 1.8V 10 8 100 1000 DATA RATE (kbps) Shutdown or Drivers Disabled Mode Driver Leakage vs Temperature 60 10–6 50 10–7 SINKING 40 30 SOURCING 20 10–8 V(TOUT) = 15V OR V(TOUT) = –15V 10–9 10–10 10 REGULATOR CAN LIMIT FURTHER 0 50 –50 –25 25 75 0 TEMPERATURE (°C) 100 125 10–11 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 2801 G12 2801 G11 2801 G10 LTC2804 Driver Outputs Exiting Shutdown Logic Input Threshold vs VL Supply Voltage 10000 2801 GO9 Driver Short-Circuit Current vs Temperature FALLING (LTC2802/04) RISING (LTC2802/04) FALLING (LTC2801/03) RISING (LTC2801/03) 70 80 2801 GO8 2801 GO7 80 RIN = ±3V CL = 150pF 0 0 LEAKAGE CURRENT (A) 0 –50 –25 0 100 VL = 5.5V VL = 3.3V VL = 1.8V 5 OUTPUT VOLTAGE (V) 2.5 THRESHOLD VOLTAGE (V) 6 POSITIVE DUTY CYCLE (%) 3.0 TA = 25°C, VCC = VL = 3.3V unless otherwise noted. LTC2804 Driver Outputs Enable/Disable 3.0 TA = 85°C TA = 25°C TA = –40°C INPUT HIGH THRESHOLD VOLTAGE (V) 2.5 2V/DIV 2V/DIV MODE AND PS MODE 2.0 1.5 T1OUT T1OUT 5V/DIV 1.0 5V/DIV T2OUT INPUT LOW T2OUT 0.5 0 1 2 3 4 5 VL SUPPLY VOLTAGE (V) 6 2801 G13 100μs/DIV VCC = 3.3V VL = 1.8V LOAD = 3k + 2.5nF 2μs/DIV VCC = 3.3V VL = 1.8V LOAD = 3k + 250nF 2801 G14 2801 G15 2801234fc 7 LTC2801/LTC2802/ LTC2803/LTC2804 PIN FUNCTIONS PIN NUMBER 2801 2802 2803 2804 VCC 3 5 5 Input Supply (1.8V-5.5V). Bypass to GND with a 1μF capacitor. VDD 4 6 6 Generated Positive Supply Voltage for RS-232 Driver (7V). Connect a 1μF capacitor between VDD and GND. VEE 13* 17* 9 Generated Negative Supply Voltage for RS-232 Driver (–6.3V). Connect a 1μF capacitor between VEE and GND. SW 5 7 7 Switch Pin. Connect a 10μH inductor between SW and VCC. GND 6 8 8 Ground. CAP 7 9 10 Charge Pump Capacitor for Generated Negative Supply Voltage. Connect a 220nF capacitor between CAP and SW. VL 10 12 12 Logic Supply (1.8V-5.5V) for the receiver outputs, driver inputs, and control inputs. This pin should be bypassed to GND with a 220nF capacitor if it’s not tied to VCC. TIN (T1IN, T2IN) 11 14, 13 14, 13 TOUT (T1OUT, T2OUT) 2 3, 4 3, 4 RS-232 Driver Output(s). RS-232 Receiver Input(s). Includes internal 5kΩ termination resistor(s). PIN NAME 2803-1 2804-1 COMMENTS Driver Input(s), referenced to VL. RIN (R1IN, R2IN) 1 1, 2 1, 2 ROUT (R1OUT, R2OUT) 12 16, 15 16, 15 PS 8 10 — Power Supply control pin, referenced to VL. Enables the integrated DC-DC converter. MODE 9 11 — Mode control pin, referenced to VL. See Table 1 for functionality. ON/OFF — — 11 Transceiver enable pin, referenced to VL. A logic low puts the device in Shutdown mode and places both driver and receiver outputs in a high impedance state. Receiver Output(s), referenced to VL. Output is short-circuit protected to GND/VCC/VL, and is high impedance in Shutdown mode, allowing data line sharing. *Backside thermal pad MODE CONTROL Table 1. LTC2801-LTC2804 MODE NAME PS MODE RECEIVER OUTPUT(S) DC-DC DRIVER OUTPUT(S) IVCC* IVL* SHUTDOWN L L HI-Z OFF HI-Z 1μA 1μA RECEIVERS ACTIVE L H ON OFF HI-Z 1μA 15μA DRIVERS DISABLED H L ON ON HI-Z 2.1mA 80μA OR 150μA NORMAL H H ON ON ON 2.3mA 80μA OR 150μA Table 2. LTC2803-1, LTC2804-1 MODE NAME ON/OFF RECEIVER OUTPUTS DC-DC DRIVER OUTPUTS IVCC* IVL* SHUTDOWN L HI-Z OFF HI-Z 1μA 1μA NORMAL H ON ON ON 2.3mA 150μA *Typical currents for static drivers. Normal mode currents are for unloaded outputs. 2801234fc 8 LTC2801/LTC2802/ LTC2803/LTC2804 FEATURE SUMMARY FEATURE 2801 2802 2803 2803-1 2804 2804-1 DRIVERS and RECEIVERS 1+1 1+1 2+2 2+2 2+2 2+2 PACKAGE DE DE DHC GN DHC GN 1.8V - 5.5V OPERATION l l l l l l 1.8V - 5.5V LOGIC SUPPLY (VL) l l l l l l SHUTDOWN (1μA) l l l l l l RECEIVER(S) ACTIVE (15μA) l l l DRIVER DISABLE l l l 100kb/s for RL = 3kΩ, CL = 2.5nF l l l l l l 250kb/s for RL = 3kΩ, CL = 1nF l l l l l l l l l l l 1Mb/s for RL = 3kΩ, CL = 250pF BLOCK DIAGRAM L1 10μH C1 220nF 1.8V TO 5.5V C4 1μF VCC SW CAP VDD VEE VL 1.8V TO 5.5V BOOST REGULATOR C5 220nF VL ** C3 1μF C2 1μF VDD T2IN T2OUT T1IN T1OUT ** VL ** R2OUT GND VEE R2IN ** 5k R1IN R1OUT VL LTC2801 LTC2802 LTC2803 LTC2804 LTC2803-1 LTC2804-1 PS MODE 5k ** GND CONTROL ON/OFF LTC2803 LTC2804 LTC2803-1 LTC2804-1 2801BD GND 2801234fc 9 LTC2801/LTC2802/ LTC2803/LTC2804 APPLICATIONS INFORMATION Overview The LTC2801 family of RS-232 transceivers operates on a VCC supply of 1.8V to 5.5V, utilizing a switching regulator to generate the necessary higher voltage rails for the drivers. The transceivers interface with logic operating on any supply from 1.8V to 5.5V, independent of the VCC voltage. Depending on the device, one or two control pins are available to invoke Shutdown, Receiver Active and Driver Disable features. The on-chip DC-DC converter operates from the VCC input, generating a 7V VDD supply and a charge pumped – 6.3V VEE supply, as shown in Figure 6. VDD and VEE power the output stage of the drivers and are regulated to levels that guarantee greater than ±5V output swing. The DC-DC converter requires a 10μH inductor (L1) and a bypass capacitor (C4) of at least 1μF. The recommended size for the charge pump capacitor (C1) is 220nF and for the storage capacitors (C2 and C3) is 1μF. Larger storage capacitors up to 4.7μF may be used if C1 is kept at 20% to 50% their size and C4 is also scaled. Locate C1-C4 close to their associated pins. L1 10μH VCC C1 220nF SW CAP C2 1μF VL C5* 220nF VCC VL EXTERNAL DEVICE RS-232 2801F07 Power-Saving Modes When the DC-DC converter and drivers are turned off (PS or ON/OFF = logic low), VCC supply current is reduced to 1μA. Tables 1 and 2 summarize the modes for each device. In Shutdown mode, VL supply current is reduced to 1μA, and both receiver and driver outputs assume a high impedance state. In Receivers Active mode, the quiescent VL supply current is reduced to 15μA and the driver outputs assume a high impedance state. The receivers operate at a reduced rate (typically 100 kbps) with hysteresis turned off. Half-Duplex Operation VDD 1.8V TO 5.5V ANY VOLTAGE FROM 1.8V TO 5.5V Figure 7. VCC and VL Are Independent DC-DC Converter 1.8V TO 5.5V C4 1μF ANY VOLTAGE FROM 1.8V TO 5.5V BOOST REGULATOR When the DC-DC converter is kept on (PS = logic high), MODE serves as a low-latency driver enable for half-duplex operation. Each driver is enabled and disabled in less than 2μs, while each receiver remains continuously active. This mode of operation is illustrated in Figures 15-17. VEE 2801F06 C3 1μF *OMIT IF VL IS CONNECTED TO VCC Figure 6. DC/DC Converter and Recommended Bypassing VL Logic Supply A separate logic supply pin VL allows the LTC2801 family to interface with any logic signal from 1.8V to 5.5V, as shown in Figure 7. Simply connect the desired logic supply to VL. There is no interdependency between VCC and VL; they may simultaneously operate at any voltage from 1.8V to 5.5V and sequence in any order. If VL is powered separately from VCC , bypass VL with a 220nF capacitor (C5). Battery Operation To maximize battery life, connect VCC (and L1) directly to the unregulated battery voltage and VL to the regulated supply, as shown in Figure 22. This configuration typically minimizes conversion loss while providing compatibility with system logic levels. Inductor Selection A 10μH inductor with a saturation current (ISAT) rating of at least 200mA and low DCR (copper wire resistance) is recommended. Some small inductors meeting these requirements are listed in Table 3. 2801234fc 10 LTC2801/LTC2802/ LTC2803/LTC2804 APPLICATIONS INFORMATION Table 3. Recommended Inductors PART NUMBER ISAT MAX DCR (mA) (Ω) SIZE (mm) MANUFACTURER LQH2MCN100K02L 225 1.2 2 × 1.6 × 0.95 Murata www.murata.com LBC2016T100K 245 0.85 2 × 1.6 × 1.6 Taiyo Yuden www.t-yuden.com FSLB2520-100K 220 1.1 2.5 × 2 × 1.6 Toko www.tokoam.com Capacitor Selection flowing through inductor L1 and capacitors C1, C2. The peak inrush current must not exceed 2A. To avoid this condition, add a 1Ω resistor as shown in Figure 8. This precaution is not relevant for supply voltages below 4.5V or rise times longer than 10μs. Board Layout The board layout should minimize the length and area of the SW and CAP traces. Suggested compact layouts for the LTC2801 family are shown in Figure 9 (a) and (b). The small size of ceramic capacitors makes them ideal for the LTC2801 family. X5R and X7R (preferred) types are recommended because their ESR is low and they retain their capacitance over relatively wide voltage and temperature ranges. Use a voltage rating of at least 10V. C1 GND C2 GND URL Murata www.murata.com TDK www.tdk.com Taiyo Yuden www.t-yuden.com AVX www.avxcorp.com Kemet www.kemet.com L1 VL Table 4. Recommended Ceramic Capacitor Manufacturers MANUFACTURER GND C5 VCC GND C4 GND TOP VIEW C3 = VIA Inrush Current and Supply Overshoot Precaution In certain applications, such as battery-operated and wall-adapter devices, fast supply slew rates are generated when power is connected. If VCC’s voltage is greater than 4.5V and its rise time is faster than 10μs, the pins VDD and SW can exceed their ABS MAX values during startup. When supply voltage is applied to VCC , the voltage difference between VCC and VDD generates inrush current L1 10μH 4.5V TO 5.5V R1 1Ω 1/8W INRUSH CURRENT C1 GND GND C2 L1 VL GND C5 VCC GND C4 C1 220nF SW CAP GND VCC C3 C4 1μF C2 1μF VDD GND TOP VIEW = VIA SCALE R1 WITH C1, C2, 1/C4 2801F08 Figure 8. Supply Overshoot Protection for Input Supplies of 4.5V or Higher 2801F09 Figure 9. Recommended Board Layouts for (a) Single and (b) Dual Transceiver Parts 2801234fc 11 LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIONS 1.8V TO 5.5V 5 LTC2803 12 1.8V TO 5.5V CELL PHONE MODE 10 LTC2804 12 VL VL 11 RA ON 5 VCC VCC 11 MODE VBATT PS 13 T2IN T2OUT 4 14 T1IN T1OUT 3 15 R2OUT R2IN 2 16 R1OUT R1IN 1 10 PS RTS TD CTS RD T2OUT 4 14 T1IN T1OUT 3 15 R2OUT R2IN 2 16 R1OUT R1IN 1 RTS TD CTS RD GND GND 8 PERIPHERAL 13 T2IN 8 2801F10 2801F11 Figure 10. Power-Saving Receivers-Active Mode 5V 3V 3 1.8V Figure 11. Cellphone Peripheral Interface 10 8 9 VCC 1.8V TO 5.5V 3 5V LTC2801 10 VL 8 PS 9 MODE μP 5 VCC LTC2802 12 VL TOUT 2 MODE OFF ON TOUT 2 11 TIN RIN 1 12 ROUT RIN 1 12 ROUT GND 6 1.8V TO 5.5V 10 8 R T 9 11 ON/OFF 13 T2IN T2OUT 4 14 T1IN T1OUT 3 15 R2OUT R2IN 2 16 R1OUT R1IN 1 GND 6 2801F12 Figure 12. 1.8V Microprocessor Interface 3 LTC2804-1 VL PS μP 11 TIN VCC GND Figure 13. 5V Microprocessor Interface 1.8V TO 5.5V 3 VCC LTC2802 10 VL 8 PS MODE R T 9 8 2801F13 Figure 14. Power-Saving Shutdown Mode 1.8V TO 5.5V 5 VCC LTC2802 12 VL 10 PS R T MODE 11 VCC LTC2803 VL PS MODE 13 T2IN TOUT 2 11 TIN TOUT 2 11 TIN RIN 1 GND 6 RIN 1 12 ROUT Figure 15. Half-Duplex on Single Line, Separate ROUT, TIN 3.3k 15 R2OUT R2IN 2 6 T1OUT 3 3.3k 16 R1OUT R1IN 1 GND GND 2801F15 T2OUT 4 14 T1IN 3.3k 12 ROUT 2801F14 2801F16 Figure 16. Half-Duplex on Single Line 8 2801F17 Figure 17. Half-Duplex Dual Transceiver 2801234fc 12 LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIONS 2.5V TO 5.5V 5 13 4 14 3 12 C4 2μF 3k CL 2801F18 DATA RATE CL (nF) LTC2803 LTC2804 (kbps) 5 X X 100 2 X X 250 0.5 X 1000 L1 10μH VCC 7 SW LTC2803 VL 9 CAP 5 C1 470nF 12 VCC SW LTC2803 VL CAP 7 9 13 T2IN T2OUT 4 13 T2IN T2OUT 4 14 T1IN T1OUT 3 14 T1IN T1OUT 3 15 R2OUT R2IN 2 15 R2OUT R2IN 2 16 R1OUT R1IN 1 16 R1OUT R1IN 1 Figure 18. Driving Larger Loads GND VDD 8 6 VEE 17 GND VDD 8 6 VEE 17 2801F19 C2 2μF C3 2μF ANY COMBINATION LTC2801/LTC2802/LTC2803/LTC2804 Figure 19. Quad Transceiver (2.5V < VCC < 5.5V) 1.8V TO 5.5V C5 220nF 12 VL LTC2803 3V TO 25V –25V TO 0V OFF ON 2 R2IN R2OUT 15 1 R2IN R1OUT 16 11 5 7 MODE PS VCC T2IN SW T1IN GND VDD 8 6 VCC = 1.8V DRIVERS DISABLED VL 0V 10 VCC = 1.8V DRIVERS LOADED VSW 5V/DIV VCC = 5.5V DRIVERS DISABLED 13 14 VEE 17 VCC = 5.5V DRIVERS LOADED 200ns/DIV 2801F21 Figure 21. Typical SW Pin Waveforms 2801F20 NOTES: 1. NO L1 OR C2-C4 NEEDED. 2. RECEIVERS ACTIVE MODE SHOWN HAS NO DC HYSTERESIS. 3. SEE DUTY CYCLE GRAPH IN TYPICAL PERFORMANCE SECTION. Figure 20. 100kbps Dual Inverting Level Translator (IL = 15μA Static) 2801234fc 13 LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIONS DE/UE Package 12-Lead Plastic DFN (4mm × 3mm) (Reference LTC DWG # 05-08-1695 Rev D) 4.00 ±0.10 (2 SIDES) 7 0.70 ±0.05 3.60 ±0.05 2.20 ±0.05 12 R = 0.05 TYP 3.30 ±0.05 1.70 ± 0.05 1.70 ± 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER 6 0.25 ± 0.05 0.75 ±0.05 0.200 REF 0.25 ± 0.05 3.30 ±0.10 3.00 ±0.10 (2 SIDES) PIN 1 TOP MARK (NOTE 6) 0.50 BSC 0.40 ± 0.10 R = 0.115 TYP 1 (UE12/DE12) DFN 0806 REV D 0.50 BSC PACKAGE OUTLINE 2.50 REF 2.50 REF BOTTOM VIEW—EXPOSED PAD 0.00 – 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED NOTE: 1. DRAWING PROPOSED TO BE A VARIATION OF VERSION (WGED) IN JEDEC PACKAGE OUTLINE M0-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE DHC Package 16-Lead Plastic DFN (5mm × 3mm) (Reference LTC DWG # 05-08-1706) R = 0.115 TYP 5.00 ±0.10 (2 SIDES) R = 0.20 TYP 0.65 ±0.05 3.50 ±0.05 1.65 ±0.05 2.20 ±0.05 (2 SIDES) 9 0.40 ± 0.10 16 3.00 ±0.10 1.65 ± 0.10 (2 SIDES) (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) PIN 1 NOTCH PACKAGE OUTLINE (DHC16) DFN 1103 8 0.25 ± 0.05 0.50 BSC 4.40 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.200 REF 1 0.25 ± 0.05 0.50 BSC 0.75 ±0.05 4.40 ±0.10 (2 SIDES) 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJED-1) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 2801234fc 14 LTC2801/LTC2802/ LTC2803/LTC2804 PACKAGE DESCRIPTION GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .189 – .196* (4.801 – 4.978) .045 ±.005 16 15 14 13 12 11 10 9 .254 MIN .009 (0.229) REF .150 – .165 .229 – .244 (5.817 – 6.198) .0165 ± .0015 .150 – .157** (3.810 – 3.988) .0250 BSC RECOMMENDED SOLDER PAD LAYOUT 1 .015 ± .004 × 45° (0.38 ± 0.10) .007 – .0098 (0.178 – 0.249) 2 3 4 5 6 7 .0532 – .0688 (1.35 – 1.75) 8 .004 – .0098 (0.102 – 0.249) 0° – 8° TYP .016 – .050 (0.406 – 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) .008 – .012 (0.203 – 0.305) TYP .0250 (0.635) BSC GN16 (SSOP) 0204 3. DRAWING NOT TO SCALE *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 2801234fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATION L1 10μH 1.8V TO 5.5V + C1 220nF C4 1μF – * 5 DC-DC 1.8V TO 5.5V 12 C5 220nF * VCC VCC 7 9 SW CAP LTC2804 VL 10 PS 11 PPX PPY TXD μP PPZ RXD MODE 13 T2IN T2OUT 4 14 T1IN T1OUT 3 15 R2OUT R2IN 2 16 R1OUT R1IN 1 GND VDD 8 6 CTS RX UART RTS TX VEE C2 1μF 17 C3 1μF 2801F22 *ADDITIONAL BYPASS CAPACITOR AS NEEDED Figure 22. Diagnostic Port Operating Directly Off Unregulated Battery Voltage RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1780/LT1781 2-Driver/2-Receiver RS232 Transceiver Single 5V Supply with 0.1μF Capacitors, 15kV ESD LTC1337 3-Driver/5-Receiver RS232 Transceiver Ultralow Power for DTE Applications LTC1338 5-Driver/3-Receiver RS232 Transceiver Ultralow Power for DCE Applications LT1039/LT1039-16 3-Driver/3-Receiver RS232 Transceiver 30kΩ Input Impedance for Multi-Drop Applications LTC1348 3-Driver/5-Receiver RS232 Transceiver True RS232 Levels on 3.3V Supply 2801234fc 16 Linear Technology Corporation LT 0808 REV C • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2005