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LTC2801/LTC2802/ LTC2803/LTC2804 1.8V to 5.5V RS-232 Single and Dual Transceivers FEATURES
n n n
DESCRIPTION
The LTC(R)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. 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 15A current. In shutdown mode, current is further reduced to 1A. Line sharing and half-duplex operation are also supported.
n n n n n n
1.8V to 5.5V Supply Voltage Single and Dual Transceivers High-Speed Operation 1Mbps for 250pF/3k Load (LTC2802, LTC2804) 250kbps for 1nF/3k Load 100kbps for 2.5nF/3k TIA/EIA-232-F Load Low-Power 1A Shutdown and 15A 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 x 3mm DFN Package LTC2803/LTC2804 Narrow SSOP-16 and 5mm x 3mm DFN Packages
PRODUCT SELECTION GUIDE
PART NUMBER LTC2801 LTC2802 LTC2803 LTC2803-1 LTC2804 LTC2804-1 DRIVERS 1 1 2 2 2 2 RECEIVERS 1 1 2 2 2 2 PACKAGE 12-Lead DFN 12-Lead DFN 16-Lead DFN 16-Lead Narrow SSOP 16-Lead DFN 16-Lead Narrow SSOP
APPLICATIONS
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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.
TYPICAL APPLICATION
1.8V TO 5.5V L1 10H
LTC2802 at 1.8V and 1Mbps
C4 1F
VCC VL PS LTC2802
SW C1 220nF CAP
2V/DIV
TIN
OFF ON
MODE TIN TOUT
5V/DIV
TOUT
ROUT
RIN
2V/DIV
ROUT
GND
VDD C2 1F
VEE C3 1F
2801 TA01a
VCC = VL = 1.8V 400ns/DIV WRAPPING DATA TOUT LOAD = 250pF + RIN ROUT LOAD = 150pF
2801 TA01b
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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 ................................................ 0C to 70C LTC280XI .............................................-40C to 85C Storage Temperature Range...................-65C to 125C Lead Temperature (Soldering, 10 sec) GN Package ...................................................... 300C
PIN CONFIGURATION
1-Driver/1-Receiver
TOP VIEW RIN TOUT VCC VDD SW GND 1 2 3 4 5 6 VEE 13 12 ROUT 11 TIN 10 VL 9 8 7 MODE PS CAP
2-Driver/2-Receiver
TOP VIEW R1IN R2IN T1OUT T2OUT VCC VDD SW GND 1 2 3 4 5 6 7 8 VEE 17 16 R1OUT 15 R2OUT 14 T1IN 13 T2IN 12 VL 11 MODE 10 PS 9 CAP
2-Driver/2-Receiver
TOP VIEW R1IN R2IN T1OUT T2OUT VCC VDD SW GND 1 2 3 4 5 6 7 8 16 R1OUT 15 R2OUT 14 T1IN 13 T2IN 12 VL 11 ON/OFF 10 CAP 9 VEE
DE PACKAGE 12-LEAD (4mm 3mm) PLASTIC DFN
TJMAX = 125C, JA = 43C/W, JC = 4.3C/W (4 Layer) EXPOSED PAD (PIN 13) IS VEE, MUST BE SOLDERED TO PCB
DHC PACKAGE 16-LEAD (5mm 3mm) PLASTIC DFN
GN PACKAGE 16-LEAD (NARROW 0.150) PLASTIC SSOP
TJMAX = 125C, JA = 44C/W, JC = 4.3C/W (4 Layer) EXPOSED PAD (PIN 17) IS VEE, MUST BE SOLDERED TO PCB
TJMAX = 125C, JA = 110C/W, JC = 40C/W (4 Layer)
ORDER INFORMATION
LEAD FREE FINISH LTC2801CDE#PBF LTC2801IDE#PBF LTC2802CDE#PBF LTC2802IDE#PBF LTC2803CDHC#PBF LTC2803IDHC#PBF LTC2804CDHC#PBF TAPE AND REEL LTC2801CDE#TRPBF LTC2801IDE#TRPBF LTC2802CDE#TRPBF LTC2802IDE#TRPBF LTC2803CDHC#TRPBF LTC2803IDHC#TRPBF LTC2804CDHC#TRPBF PART MARKING* 2801 2801 2802 2802 2803 2803 2804 PACKAGE DESCRIPTION 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 16-Lead (5mm x 3mm) Plastic DFN 16-Lead (5mm x 3mm) Plastic DFN 16-Lead (5mm x 3mm) Plastic DFN TEMPERATURE RANGE 0C to 70C -40C to 85C 0C to 70C -40C to 85C 0C to 70C -40C to 85C 0C to 70C
LTC2804IDHC#PBF LTC2804IDHC#TRPBF 2804 -40C to 85C 16-Lead (5mm x 3mm) Plastic DFN LTC2803CGN-1#PBF LTC2803CGN-1#TRPBF 28031 16-Lead (Narrow 0.150) Plastic SSOP 0C to 70C LTC2803IGN-1#PBF LTC2803IGN-1#TRPBF 2803I1 16-Lead (Narrow 0.150) Plastic SSOP -40C to 85C LTC2804CGN-1#PBF LTC2804CGN-1#TRPBF 28041 16-Lead (Narrow 0.150) Plastic SSOP 0C to 70C LTC2804IGN-1#PBF LTC2804IGN-1#TRPBF 2804I1 16-Lead (Narrow 0.150) Plastic SSOP -40C to 85C 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/
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LTC2801/LTC2802/ LTC2803/LTC2804 ELECTRICAL CHARACTERISTICS
SYMBOL Power Supplies ICC VCC Supply Current Outputs Unloaded Normal Mode (Note 3) Receivers Active Mode Shutdown Mode Outputs Unloaded Normal Mode (LTC2801, LTC2802) Normal Mode (LTC2803, LTC2804) Receivers Active Mode Shutdown Mode RL = 3k RL = 3k VL = VCC = 5.5V; VTOUT = 0V VL = VCC = VDD = VEE = 0V; VTOUT = 2V Low High 2.3 1 1 0.08 0.15 15 1 -5 5 -5.7 6.2 0.6
l l
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C, 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 = 25C, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
l l l l l l l l
10 10 0.15 0.30 30 10
mA A A mA mA A A V V V
IL
VL Supply Current
Driver VOLD VOHD VHYSD IOSD IPOLD IOLD Receiver VIR VILR VIHR VHYSR VOLR VOHR RIN IOSR Logic Logic Input Voltage Threshold IIN VDD Logic Input Current Regulated VDD Output Voltage Driver RL = 3k (Note 3) LTC2801, LTC2802: VTIN = VL LTC2803, LTC2804: VT1IN = VL , VT2IN = 0V Driver RL = 3k (Note 3) LTC2801, LTC2802: VTIN = VL LTC2803, LTC2804: VT1IN = VL , VT2IN = 0V Power Supply Generator 7 V
l l
Output Voltage Output Voltage Logic Input Hysteresis Output Short Circuit Current Power-Off Output Leakage Current Output Leakage Current
35 0.1 0.1
70 10 10
mA A A
l Shutdown or Receivers Active or Drivers Disabled Modes, -15V VTOUT 15V
Input Thresholds Input Thresholds Input Thresholds Input Hysteresis Output Voltage Output Voltage Input Resistance Output Short Circuit Current
Receivers Active Mode Normal Mode, Input Low Normal Mode, Input High Normal Mode Output Low, IROUT = 1mA (Sinking) Output High, IROUT = -1mA (Sourcing) -15V VRIN 15V VL = 5.5V; 0V VROUT VL
l l l l l l l l
0.8 0.8 0.1 VL -0.4 3
1.5 1.3 1.7 0.4 0.2 VL -0.2 5 25
2.4 2.5 1.0 0.4 7 50 0.67 * VL 1
V V V V V V k mA V A
0.4
VEE
Regulated VEE Output Voltage
- 6.3
V
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LTC2801/LTC2802/ LTC2803/LTC2804 SWITCHING CHARACTERISTICS
SYMBOL PARAMETER Maximum Data Rate
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C, 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 = 25C, unless otherwise noted.
CONDITIONS LTC2801, LTC2803 (Note 3) RL = 3k, CL = 2.5nF RL = 3k, CL = 1nF LTC2802, LTC2804 (Note 3) RL = 3k, CL = 2.5nF RL = 3k, CL = 1nF RL = 3k, CL = 250pF Driver SR(D) Driver Slew Rate LTC2801, LTC2803 (Figure 1) VCC = VL = 1.8V, RL = 3k, CL = 2.5nF VCC = VL = 5.5V, RL = 3k, CL = 50pF LTC2802, LTC2804 (Figure 1) VCC = VL = 1.8V, RL = 3k, CL = 2.5nF VCC = VL = 5.5V, RL = 3k, CL = 50pF tPHLD, tPLHD Driver Propagation Delay RL = 3k, CL = 50pF (Figure 2) LTC2801, LTC2803 LTC2802, LTC2804 RL = 3k, CL = 50pF (Figure 2) LTC2801, LTC2803 LTC2802, LTC2804 PS = VL, MODE = , RL = 3k, CL = 50pF (Figure 4) PS = VL, MODE = , RL = 3k, CL = 50pF (Figure 4) CL = 150pF (Figure 3) CL = 150pF (Figure 3) CL = 150pF (Figure 3) PS = MODE = or ON/OFF = , RL = 1k, CL = 150pF (Figure 5) PS = MODE = or ON/OFF = , RL = 1k, CL = 150pF (Figure 5) (Notes 3 and 4)
l l l l l l l l l l l l l l l l
MIN 100 250 100 250 1000
TYP
MAX
UNITS kbps kbps kbps kbps kbps
4 30 4 150 1 0.2 100 50 0.6 0.3 2 2 2 0.5
V/s V/s V/s V/s s s ns ns s s
tSKEWD
Driver Skew
tPZHD, tPZLD tPHZD, tPLZD Receiver tPHLR, tPLHR tSKEWR tRR, tFR tPZHR, tPZLR tPHZR, tPLZR
Driver Output Enable Time Driver Output Disable Time
Receiver Propagation Delay Receiver Skew Receiver Rise or Fall Time Shutdown to Receiver Output Enable Receiver Output Disable upon Shutdown
l
0.2 50 60 5 0.15
0.4 200 15 0.3
s ns ns s s
Power Supply Generator VDD/VEE Supply Rise Time
l
0.2
2
ms
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.
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LTC2801/LTC2802/ LTC2803/LTC2804 TEST CIRCUITS
TOUT TIN tTHL TOUT SR(D) = TIN tr, tf 40ns 6V tTHL or tTLH 3V -3V 3V -3V tTLH VOHD VOLD
2801F02
VL 0V
TIN
RL
CL
Figure 1. Driver Slew Rate Measurement
TOUT TIN TIN RL CL TOUT 1/2 VL tPHLD 0V tSKEWD = |tPHLD - tPLHD| TIN tr, tf 40ns 1/2 VL
VL 0V tPLHD VOHD 0V VOLD
2801F02
Figure 2. Driver Timing Measurement
ROUT
RIN
3V 1.5V tPHLR 1.5V -3V tPLHR VOHR 1/2 VL tSKEWR = |tPHLR - tPLHR| 1/2 VL VOLR
2801F03
RIN
CL ROUT
RIN tr, tf 40ns
Figure 3. Receiver Timing Measurement
MODE
VL 1/2 VL tPZHD 1/2 VL 0V tPHZD 5V tPZLD tPLZD 0V -5V VOLD + 0.5V VOLD VOHD - 0.5V VOHD 0V
0 OR VL RL CL
TOUT TOUT MODE
TOUT
2801F04
MODE tr, tf 40ns
Figure 4. Driver Enable/Disable Times
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LTC2801/LTC2802/ LTC2803/LTC2804 TEST CIRCUITS
GND VL PS AND MODE RL -3V OR 3V ROUT ROUT PS AND MODE CL ROUT PS AND MODE tr, tf 40ns tPZLR 1/2 VL VL 1/2 VL tPZHR 1/2 VL tPLZR VL VOLR + 0.5V VOLR
2801F05
1/2 VL 0V tPHZR V VOHR - 0.5V OHR 0V
Figure 5. Receiver Enable/Disable Times
TYPICAL PERFORMANCE CHARACTERISTICS
LTC2803 at 1.8V and 250kbps
T1IN 2V/DIV T1OUT T2OUT 10V/DIV R1OUT 2V/DIV R2OUT 2V/DIV 10V/DIV R1OUT R2OUT 2V/DIV T1OUT T2OUT
TA = 25C, VCC = VL = 3.3V unless otherwise noted.
LTC2804 at 1.8V and 1Mbps
3.0 T1IN SUPPLY CURRENT (mA) 2.5
Drivers Disabled Mode Supply Current vs Supply Voltage
TA = 85C TA = 25C TA = -40C VCC = VL
2.0 1.5 1.0 0.5 0
VCC = VL = 1.8V 2s/DIV WRAPPING DATA TOUT LOAD = 1nF + RIN ROUT LOAD = 150pF
2801 G01
VCC = VL = 1.8V 400ns/DIV WRAPPING DATA TOUT LOAD = 250pF + RIN ROUT LOAD = 150pF
1
2
5 3 4 SUPPLY VOLTAGE (V)
6
2801 G03
2801 G02
Supply Current vs Supply Voltage (Dual Transceiver)
60 50 SUPPLY CURRENT (mA) 40 125kbps 30 20 10 LTC2804 LTC2803 0 1 2 3 4 5 SUPPLY VOLTAGE (V) 6
2801 G04
Supply Current vs Data Rate
100 ALL DRIVERS SWITCHING VCC = VL = 1.8V RL = 3k 1nF 1nF 60 250pF 40 250pF LTC2804 LTC2802 0 200 600 400 DATA RATE (kbps) 800 1000
2801 G05
Supply Current vs Load Capacitance (Dual Transceiver)
100 250kbps 80 SUPPLY CURRENT (mA) 125kbps
SUPPLY CURRENT (mA)
ALL DRIVERS SWITCHING VCC = VL RL = 3k 250kbps CL = 1nF
80
60
40 20.8kbps 20 VCC = VL = 1.8V LTC2804 RL = 3k LTC2803 ALL DRIVERS SWITCHING 1 3 2 4 LOAD CAPACITANCE (nF) 5
2801 G06
20.8kbps
20
0
0
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LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Input Threshold vs Temperature
3.0 2.5 THRESHOLD VOLTAGE (V) 2.0 1.5 1.0 0.5 0 -50 -25 INPUT LOW VL = 5.5V VL = 3.3V VL = 1.8V INPUT HIGH OUTPUT VOLTAGE (V) 6 5 4 3 2 1 0
TA = 25C, VCC = VL = 3.3V unless otherwise noted.
Receiver Output Voltage vs Load Current
VL = 5.5V VL = 3.3V VL = 1.8V POSITIVE DUTY CYCLE (%) 100
Receiver Output Duty Cycle
RIN = 3V CL = 150pF RECEIVERS ALIVE MODE 60 NORMAL MODE
80
40
20
0 0 1 2 3 4 5 6 LOAD CURRENT (mA) 7 8 10 100 1000 DATA RATE (kbps)
VL = 5.5V VL = 3.3V VL = 1.8V 10000
2801 GO9
50 25 75 0 TEMPERATURE (C)
100
125
2801 GO7
2801 GO8
Driver Slew Rate vs Load Capacitance
80 70 60 SLEW RATE (V/s) 50 40 30 20 10 0 0 1 4 3 LOAD CAPACITANCE (nF) 2 5
2801 G10
Driver Short-Circuit Current vs Temperature
60 SHORT-CIRCUIT CURRENT (mA) 50 SINKING 40 30 20 10 REGULATOR CAN LIMIT FURTHER 0 50 -50 -25 25 75 0 TEMPERATURE (C) SOURCING LEAKAGE CURRENT (A) 10-6 10-7 10-8 10-9
Shutdown or Drivers Disabled Mode Driver Leakage vs Temperature
FALLING (LTC2802/04) RISING (LTC2802/04) FALLING (LTC2801/03) RISING (LTC2801/03)
V(TOUT) = 15V OR V(TOUT) = -15V
10-10 10-11 -50 -25
100
125
50 25 75 0 TEMPERATURE (C)
100
125
2801 G11
2801 G12
Logic Input Threshold vs VL Supply Voltage
3.0 2.5 THRESHOLD VOLTAGE (V) 2.0 1.5 1.0 INPUT LOW 0.5 0 5V/DIV TA = 85C TA = 25C TA = -40C INPUT HIGH
LTC2804 Driver Outputs Exiting Shutdown
LTC2804 Driver Outputs Enable/Disable
2V/DIV
MODE AND PS
2V/DIV
MODE
T1OUT 5V/DIV T2OUT
T1OUT T2OUT
1
2
3 4 5 VL SUPPLY VOLTAGE (V)
6
2801 G13
100s/DIV VCC = 3.3V VL = 1.8V LOAD = 3k + 2.5nF
2801 G14
2s/DIV VCC = 3.3V VL = 1.8V LOAD = 3k + 250nF
2801 G15
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LTC2801/LTC2802/ LTC2803/LTC2804 PIN FUNCTIONS
PIN NUMBER PIN NAME VCC VDD VEE SW GND CAP VL TIN (T1IN, T2IN) TOUT (T1OUT, T2OUT) RIN (R1IN, R2IN) ROUT (R1OUT, R2OUT) PS MODE ON/OFF *Backside thermal pad 2801 2802 3 4 13* 5 6 7 10 11 2 1 12 8 9 -- 2803 2804 5 6 17* 7 8 9 12 14, 13 3, 4 1, 2 16, 15 10 11 -- 2803-1 2804-1 COMMENTS 5 6 9 7 8 10 12 14, 13 3, 4 1, 2 16, 15 -- -- 11 Input Supply (1.8V-5.5V). Bypass to GND with a 1F capacitor. Generated Positive Supply Voltage for RS-232 Driver (7V). Connect a 1F capacitor between VDD and GND. Generated Negative Supply Voltage for RS-232 Driver (-6.3V). Connect a 1F capacitor between VEE and GND. Switch Pin. Connect a 10H inductor between SW and VCC. Ground. Charge Pump Capacitor for Generated Negative Supply Voltage. Connect a 220nF capacitor between CAP and SW. 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. Driver Input(s), referenced to VL. RS-232 Driver Output(s). RS-232 Receiver Input(s). Includes internal 5k termination resistor(s). 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. Power Supply control pin, referenced to VL. Enables the integrated DC-DC converter. Mode control pin, referenced to VL. See Table 1 for functionality. 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.
MODE CONTROL
Table 1. LTC2801-LTC2804
MODE NAME SHUTDOWN RECEIVERS ACTIVE DRIVERS DISABLED NORMAL PS L L H H MODE L H L H RECEIVER OUTPUT(S) HI-Z ON ON ON DC-DC OFF OFF ON ON DRIVER OUTPUT(S) HI-Z HI-Z HI-Z ON IVCC* 1A 1A 2.1mA 2.3mA IVL* 1A 15A 80A OR 150A 80A OR 150A
Table 2. LTC2803-1, LTC2804-1
MODE NAME SHUTDOWN NORMAL ON/OFF L H RECEIVER OUTPUTS HI-Z ON DC-DC OFF ON DRIVER OUTPUTS HI-Z ON IVCC* 1A 2.3mA IVL* 1A 150A
*Typical currents for static drivers. Normal mode currents are for unloaded outputs.
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LTC2801/LTC2802/ LTC2803/LTC2804 FEATURE SUMMARY
FEATURE DRIVERS and RECEIVERS PACKAGE 1.8V - 5.5V OPERATION 1.8V - 5.5V LOGIC SUPPLY (VL) SHUTDOWN (1A) RECEIVER(S) ACTIVE (15A) DRIVER DISABLE 100kb/s for RL = 3k, CL = 2.5nF 250kb/s for RL = 3k, CL = 1nF 1Mb/s for RL = 3k, CL = 250pF 2801 1+1 DE
l l l l l l l
2802 1+1 DE
l l l l l l l l
2803 2+2 DHC
l l l l l l l
2803-1 2+2 GN
l l l
2804 2+2 DHC
l l l l l
2804-1 2+2 GN
l l l
l l
l l l
l l l
BLOCK DIAGRAM
L1 10H 1.8V TO 5.5V C4 1F VCC SW CAP VDD 1.8V TO 5.5V C5 220nF VL BOOST REGULATOR VEE C3 1F C2 1F C1 220nF
VL T2IN T1IN
VDD T2OUT T1OUT VL
**
**
**
R2OUT
GND
VEE
R2IN
**
5k R1OUT VL LTC2801 LTC2802 LTC2803 LTC2804 LTC2803-1 LTC2804-1 PS MODE ON/OFF GND CONTROL 5k ** LTC2803 LTC2804 LTC2803-1 LTC2804-1 R1IN
2801BD
GND
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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. DC-DC Converter 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 10H inductor (L1) and a bypass capacitor (C4) of at least 1F The recommended . size for the charge pump capacitor (C1) is 220nF and for the storage capacitors (C2 and C3) is 1F Larger storage . capacitors up to 4.7F 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 10H 1.8V TO 5.5V C4 1F VCC C1 220nF SW CAP VDD 1.8V TO 5.5V C5* 220nF VL BOOST REGULATOR VEE C3 1F C2 1F
ANY VOLTAGE FROM 1.8V TO 5.5V
ANY VOLTAGE FROM 1.8V TO 5.5V VCC VL
EXTERNAL DEVICE
RS-232
2801F07
Figure 7. VCC and VL Are Independent
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 1A. Tables 1 and 2 summarize the modes for each device. In Shutdown mode, VL supply current is reduced to 1A, and both receiver and driver outputs assume a high impedance state. In Receivers Active mode, the quiescent VL supply current is reduced to 15A 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 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 2s, while each receiver remains continuously active. This mode of operation is illustrated in Figures 15-17. 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 10H 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.
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2801F06
*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).
10
LTC2801/LTC2802/ LTC2803/LTC2804 APPLICATIONS INFORMATION
Table 3. Recommended Inductors
PART NUMBER ISAT MAX DCR (mA) () 1.2 0.85 1.1 SIZE (mm) MANUFACTURER
LQH2MCN100K02L 225 LBC2016T100K FSLB2520-100K 245 220
2 x 1.6 x 0.95 Murata www.murata.com 2 x 1.6 x 1.6 Taiyo Yuden www.t-yuden.com 2.5 x 2 x 1.6 Toko www.tokoam.com
flowing through inductor L1 and capacitors C1, C2. The peak inrush current must not exceed 2A. To avoid this condition, add a 1 resistor as shown in Figure 8. This precaution is not relevant for supply voltages below 4.5V or rise times longer than 10s. 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).
Capacitor Selection 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.
Table 4. Recommended Ceramic Capacitor Manufacturers
MANUFACTURER Murata TDK Taiyo Yuden AVX Kemet URL www.murata.com www.tdk.com www.t-yuden.com www.avxcorp.com www.kemet.com
C1
GND
GND C2 VL GND C5 VCC GND C4 L1
GND TOP VIEW = VIA C3
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 10s, 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
4.5V TO 5.5V INRUSH CURRENT VCC C3 C4 1F C2 1F SCALE R1 WITH C1, C2, 1/C4
2801F08
C1
GND
GND C2 VL GND C5 VCC GND C4 L1
L1 10H
C1 220nF
R1 1 1/8W
SW
CAP
GND
VDD
GND TOP VIEW = VIA
2801F09
Figure 8. Supply Overshoot Protection for Input Supplies of 4.5V or Higher
Figure 9. Recommended Board Layouts for (a) Single and (b) Dual Transceiver Parts
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11
LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIONS
1.8V TO 5.5V 5 12 11 RA ON 10 VCC LTC2803 VL MODE PS T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 GND 8
2801F10
5 VCC 12 VL 1.8V TO 5.5V CELL PHONE VBATT RTS TD CTS RD 10 PS 11 MODE 13 T2IN 14 T1IN 15 R2OUT 16 R1OUT GND 8
2801F11
LTC2804
PERIPHERAL T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 RTS TD CTS RD
13 T2IN 14 T1IN 15 R2OUT 16 R1OUT
Figure 10. Power-Saving Receivers-Active Mode
5V 3 10 8 9 P 11 TIN TOUT 2 VCC LTC2801 VL PS MODE P 11 TIN 3V 3 10 8 9 VCC LTC2802 VL PS MODE
Figure 11. Cellphone Peripheral Interface
1.8V TO 5.5V 5 12 VCC LTC2804-1 VL
1.8V
5V
OFF ON
11
ON/OFF T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 GND
13 T2IN TOUT 2 14 T1IN 15 R2OUT
12 ROUT GND 6
RIN 1
12 ROUT GND
RIN 1
16 R1OUT
2801F12
6
2801F13
8
2801F14
Figure 12. 1.8V Microprocessor Interface
1.8V TO 5.5V 3 10 8 RT 9 VCC LTC2802 VL PS MODE
Figure 13. 5V Microprocessor Interface
1.8V TO 5.5V 3 10 8 RT 9 VCC LTC2802 VL PS MODE
Figure 14. Power-Saving Shutdown Mode
1.8V TO 5.5V 5 12 10 RT 11 VCC LTC2803 VL PS MODE T2OUT 4 R2IN 2 T1OUT 3 R1IN 1 GND
13 T2IN 11 TIN TOUT 2 3.3k 12 ROUT GND 6
2801F15
11 TIN
TOUT 2
3.3k 15 R2OUT 14 T1IN
RIN 1
12 ROUT GND 6
RIN 1
3.3k 16 R1OUT
2801F16
8
2801F17
Figure 15. Half-Duplex on Single Line, Separate ROUT, TIN
Figure 16. Half-Duplex on Single Line
Figure 17. Half-Duplex Dual Transceiver
2801234fc
12
LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIONS
2.5V TO 5.5V L1 10H
5 13 4 C4 2F 12
VCC LTC2803 VL
SW CAP
7 9 C1 470nF
5 12
VCC LTC2803 VL
SW CAP
7 9
14
3 3k CL
2801F18
13 T2IN 14 T1IN 15 R2OUT 16 R1OUT GND VDD 6
T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 VEE 17
13 T2IN 14 T1IN 15 R2OUT 16 R1OUT GND 8 VDD 6
T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 VEE 17
DATA RATE CL (nF) LTC2803 LTC2804 (kbps) 5 X X 100 2 X X 250 0.5 X 1000
Figure 18. Driving Larger Loads
8
2801F19
C2 2F
C3 2F
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 2 R2IN 1 R2IN R2OUT 15 R1OUT 16 VL 0V VSW 5V/DIV VCC = 1.8V DRIVERS DISABLED VCC = 1.8V DRIVERS LOADED VCC = 5.5V DRIVERS DISABLED
OFF ON
11 5 7
MODE VCC SW GND 8
PS T2IN T1IN VDD 6 VEE 17
10 13 14
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 = 15A Static)
2801234fc
13
LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIONS
DE/UE Package 12-Lead Plastic DFN (4mm x 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
4.00 0.10 (2 SIDES) 0.70 0.05 3.30 0.05 1.70 0.05 PIN 1 TOP MARK (NOTE 6) R = 0.05 TYP 3.00 0.10 (2 SIDES) 3.30 0.10 1.70 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 x 45 CHAMFER 1 0.50 BSC 2.50 REF 0.00 - 0.05 BOTTOM VIEW--EXPOSED PAD
(UE12/DE12) DFN 0806 REV D
7
R = 0.115 TYP
0.40 0.10 12
3.60 0.05 2.20 0.05
0.25 0.05 0.50 BSC 2.50 REF 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 PACKAGE OUTLINE
0.200 REF
0.75 0.05
6 0.25 0.05
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 x 3mm)
(Reference LTC DWG # 05-08-1706)
5.00 0.10 (2 SIDES) 0.65 0.05 R = 0.20 TYP R = 0.115 TYP 9 16 0.40 0.10
3.50 0.05
1.65 0.05 2.20 0.05 (2 SIDES)
PIN 1 TOP MARK (SEE NOTE 6) PACKAGE OUTLINE
3.00 0.10 1.65 0.10 (2 SIDES) (2 SIDES) PIN 1 NOTCH
(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 0.75 0.05 4.40 0.10 (2 SIDES)
1 0.25 0.05 0.50 BSC
0.00 - 0.05 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
BOTTOM VIEW--EXPOSED PAD
2801234fc
14
LTC2801/LTC2802/ LTC2803/LTC2804 PACKAGE DESCRIPTION
GN Package 16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.045 .005 .189 - .196* (4.801 - 4.978) 16 15 14 13 12 11 10 9 .009 (0.229) REF
.254 MIN
.150 - .165 .229 - .244 (5.817 - 6.198) .150 - .157** (3.810 - 3.988)
.0165 .0015
.0250 BSC 1 .015 .004 x 45 (0.38 0.10) .0532 - .0688 (1.35 - 1.75) 23 4 56 7 8 .004 - .0098 (0.102 - 0.249)
RECOMMENDED SOLDER PAD LAYOUT
.007 - .0098 (0.178 - 0.249)
0 - 8 TYP
.016 - .050 (0.406 - 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 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
.008 - .012 (0.203 - 0.305) TYP
.0250 (0.635) BSC
GN16 (SSOP) 0204
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
1.8V TO 5.5V L1 10H C4 1F * DC-DC 1.8V TO 5.5V C5 220nF 5 12 10 PS PPX PPY TXD P PPZ RXD 11 MODE T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 CTS RX UART RTS TX VCC VL 7 SW 9 CAP C1 220nF
+ -
LTC2804
* VCC
13 T2IN 14 T1IN 15 R2OUT 16 R1OUT
GND 8
VDD 6 C2 1F
VEE 17 C3 1F
2801F22
*ADDITIONAL BYPASS CAPACITOR AS NEEDED
Figure 22. Diagnostic Port Operating Directly Off Unregulated Battery Voltage
RELATED PARTS
PART NUMBER LT1780/LT1781 LTC1337 LTC1338 LT1039/LT1039-16 LTC1348 DESCRIPTION 2-Driver/2-Receiver RS232 Transceiver 3-Driver/5-Receiver RS232 Transceiver 5-Driver/3-Receiver RS232 Transceiver 3-Driver/3-Receiver RS232 Transceiver 3-Driver/5-Receiver RS232 Transceiver COMMENTS Single 5V Supply with 0.1F Capacitors, 15kV ESD Ultralow Power for DTE Applications Ultralow Power for DCE Applications 30k Input Impedance for Multi-Drop Applications True RS232 Levels on 3.3V Supply
2801234fc
16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0808 REV C * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005

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