LTC2801/LTC2802/
LTC2803/LTC2804
1.8V to 5.5V RS-232
Single and Dual Transceivers
Features
Description
1.8V to 5.5V Supply Voltage
n Single and Dual Transceivers
n 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
n Low-Power 1µA Shutdown and 15µA ReceiversActive Modes
n No Damage or Latchup to ±10kV ESD on RS-232
Interface
n Logic Supply Pin for Easy Level-Shifting to UART or
Microprocessor
n Low-Latency Output Enable Allows Line Sharing and
Half-Duplex Operation
n True RS-232 Compliant Output Levels
n Small Footprint:
LTC2801/LTC2802 4mm × 3mm DFN Package
LTC2803/LTC2804 Narrow SSOP-16 and
5mm × 3mm DFN Packages
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.
LTC2801
1+1
Applications
LTC2802
1+1
n
Battery-Powered Systems
n Computers and Consumer Electronics
n Diagnostic Ports
n
L, LT, LTC, LTM, Linear Technology and the Linear logo 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.
Product Selection Guide
PART NUMBER
DRIVERS AND MAXIMUM
RECEIVERS DATA RATE
MODES*
PACKAGE
0.25Mbps SD, RA, DD, AO
1Mbps
DFN-12
SD, RA, DD, AO
DFN-12
LTC2803
2+2
0.25Mbps SD, RA, DD, AO
DFN-16
LTC2803-1
2+2
0.25Mbps
SD, AO
SSOP-16
LTC2804
2+2
1Mbps
SD, RA, DD, AO
DFN-16
LTC2804-1
2+2
1Mbps
SD, AO
SSOP-16
*SD = Shutdown, RA = Receiver Active (low power), DD = Drivers
Disabled, AO = All On
Typical Application
1.8V TO 5.5V
C4
1µF
LTC2802 at 1.8V and 1Mbps
L1
10µH
SW
VCC
VL
LTC2802
MODE
TIN
5V/DIV
TOUT
TOUT
TIN
RIN
ROUT
GND
2V/DIV
CAP
PS
OFF ON
C1
220nF
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
2801234fe
LTC2801/LTC2802/
LTC2803/LTC2804
Absolute Maximum Ratings
(Note 1)
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
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
Pin Configuration
LTC2801, LTC2802
1-Driver/1-Receiver
LTC2803, LTC2804
2-Driver/2-Receiver
LTC2803-1, LTC2804-1
2-Driver/2-Receiver
TOP VIEW
TOP VIEW
TOP VIEW
R1IN
1
16 R1OUT
R1IN
1
16 R1OUT
R2IN
2
15 R2OUT
R2IN
2
15 R2OUT
RIN
1
12 ROUT
TOUT
2
11 TIN
T1OUT
3
14 T1IN
T1OUT
3
14 T1IN
VCC
3
10 VL
T2OUT
4
13 T2IN
T2OUT
4
13 T2IN
VDD
4
VCC
5
12 VL
SW
5
VDD
6
11 ON/OFF
GND
6
SW
7
10 CAP
GND
8
9
13
VEE
17
9
MODE
VCC
5
8
PS
VDD
6
11 MODE
7
CAP
SW
7
10 PS
GND
8
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
VEE
12 VL
9
CAP
DHC PACKAGE
16-LEAD (5mm s 3mm) PLASTIC DFN
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
VEE
GN PACKAGE
16-LEAD (NARROW 0.150) PLASTIC SSOP
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/
2801234fe
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
Power Supplies
ICC
IL
VL Supply Current
Driver
VOLD
Output Voltage
RL = 3kΩ
Low
l
–5
–5.7
V
RL = 3kΩ
High
l
5
6.2
V
0.6
V
VOHD
Output Voltage
VHYSD
Logic Input Hysteresis
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
V
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
kW
IOSR
Output Short Circuit Current
VL = 5.5V; 0V ≤ VROUT ≤ VL
l
±25
±50
mA
V
Logic
IIN
Logic Input Voltage Threshold
l
Logic Input Current
l
0.4
0.67 • VL
V
±1
µA
Power Supply Generator
VDD
Regulated VDD Output Voltage
Driver RL = 3kW (Note 3)
LTC2801, LTC2802: VTIN = VL
LTC2803, LTC2804: VT1IN = VL , VT2IN = 0V
7
V
VEE
Regulated VEE Output Voltage
Driver RL = 3kW (Note 3)
LTC2801, LTC2802: VTIN = VL
LTC2803, LTC2804: VT1IN = VL , VT2IN = 0V
– 6.3
V
2801234fe
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 = 3kW, CL = 2.5nF
RL = 3kW, CL = 1nF
MIN
TYP
MAX
UNITS
l
l
100
250
kbps
kbps
LTC2802, LTC2804 (Note 3)
RL = 3kW, CL = 2.5nF
RL = 3kW, CL = 1nF
RL = 3kW, CL = 250pF
l
l
l
100
250
1000
kbps
kbps
kbps
LTC2801, LTC2803 (Figure 1)
VCC = VL = 1.8V, RL = 3kW, CL = 2.5nF
VCC = VL = 5.5V, RL = 3kW, CL = 50pF
l
l
4
LTC2802, LTC2804 (Figure 1)
VCC = VL = 1.8V, RL = 3kW, CL = 2.5nF
VCC = VL = 5.5V, RL = 3kW, CL = 50pF
l
l
4
RL = 3kW, CL = 50pF (Figure 2)
LTC2801, LTC2803
LTC2802, LTC2804
l
l
Driver
SR(D)
tPHLD, tPLHD
Driver Slew Rate
Driver Propagation Delay
1
0.2
30
V/µs
V/µs
150
V/µs
V/µs
2
0.5
µs
µs
tSKEWD
Driver Skew
RL = 3kW, CL = 50pF (Figure 2)
LTC2801, LTC2803
LTC2802, LTC2804
tPZHD, tPZLD
Driver Output Enable Time
PS = VL, MODE = ↑, RL = 3kW, CL = 50pF
(Figure 4)
l
0.6
2
µs
tPHZD, tPLZD
Driver Output Disable Time
PS = VL, MODE = ↓, RL = 3kW, CL = 50pF
(Figure 4)
l
0.3
2
µs
tPHLR, tPLHR
Receiver Propagation Delay
CL = 150pF (Figure 3)
l
0.2
0.4
µs
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 = 1kW, CL = 150pF (Figure 5)
l
5
15
µs
tPHZR, tPLZR
Receiver Output Disable upon Shutdown
PS = MODE = ↓ or ON/OFF = ↓,
RL = 1kW, CL = 150pF (Figure 5)
l
0.15
0.3
µs
(Notes 3 and 4)
l
0.2
2
ms
100
50
ns
ns
Receiver
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.
2801234fe
LTC2801/LTC2802/
LTC2803/LTC2804
Test Circuits
TOUT
RL
TIN
VL
TIN
CL
tTHL
3V
–3V
TOUT
SR(D) =
TIN tr, tf ≤ 40ns
tTLH
6V
3V
–3V
0V
VOHD
VOLD
2801 F01
tTHL or tTLH
Figure 1. Driver Slew Rate Measurement
TOUT
TIN
RL
TIN
1/2 VL
CL
VL
1/2 VL
tPHLD
0V
TOUT
0V
tPLHD
0V
tSKEWD = |tPHLD – tPLHD|
VOHD
VOLD
2801 F02
TIN tr, tf ≤ 40ns
Figure 2. Driver Timing Measurement
ROUT
RIN
1.5V
CL
RIN
3V
1.5V
tPHLR
ROUT
–3V
tPLHR
1/2 VL
1/2 VL
tSKEWR = |tPHLR – tPLHR|
VOHR
VOLR
2801 F03
RIN tr, tf ≤ 40ns
Figure 3. Receiver Timing Measurement
MODE
0 OR VL
TOUT
MODE
RL
1/2 VL
VL
1/2 VL
tPZHD
5V
TOUT
0V
tPHZD
VOHD – 0.5V
VOHD
0V
CL
tPZLD
TOUT
tPLZD
–5V
0V
VOLD + 0.5V
VOLD
2801 F04
MODE tr, tf ≤ 40ns
Figure 4. Driver Enable/Disable Times
2801234fe
LTC2801/LTC2802/
LTC2803/LTC2804
Test Circuits
GND
VL
PS AND MODE
RL
–3V OR 3V
VL
1/2 VL
tPZHR
ROUT
PS AND MODE
1/2 VL
ROUT
tPHZR
1/2 VL
CL
V
VOHR – 0.5V OHR
0V
tPZLR
ROUT
0V
tPLZR
1/2 VL
VL
VOLR + 0.5V
VOLR
2801 F05
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
T2OUT
10V/DIV
R1OUT
VCC = VL = 1.8V
2µs/DIV
WRAPPING DATA
TOUT LOAD = 1nF + RIN
ROUT LOAD = 150pF
2801 G01
125kbps
20.8kbps
LTC2804
LTC2803
1
2
3
4
5
SUPPLY VOLTAGE (V)
6
2801 G04
250kbps
1nF
250pF
600
400
DATA RATE (kbps)
800
125kbps
60
40
20.8kbps
20
LTC2804
LTC2802
200
6
2801 G03
80
40
0
5
3
4
SUPPLY VOLTAGE (V)
100
250pF
0
2
Supply Current vs Load
Capacitance (Dual Transceiver)
60
20
10
0
1nF
1
2801 G02
ALL DRIVERS SWITCHING
VCC = VL = 1.8V
RL = 3k
80
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
100
40
20
0
Supply Current vs Data Rate
ALL DRIVERS SWITCHING
VCC = VL
RL = 3k
250kbps
CL = 1nF
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)
60
1.0
R2OUT
2V/DIV
TA = –40°C
1.5
R1OUT
R2OUT
2V/DIV
TA = 25°C
2.0
SUPPLY CURRENT (mA)
10V/DIV
30
SUPPLY CURRENT (mA)
2V/DIV
VCC = VL
TA = 85°C
T1IN
1000
2801 G05
0
VCC = VL = 1.8V
LTC2804
RL = 3k
LTC2803 ALL DRIVERS SWITCHING
1
3
2
4
LOAD CAPACITANCE (nF)
5
2801 G06
2801234fe
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
2.5
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
0
1
2
3
4
5
6
LOAD CURRENT (mA)
Driver Slew Rate
vs Load Capacitance
SLEW RATE (V/µs)
60
SHORT-CIRCUIT CURRENT (mA)
70
50
40
30
20
10
0
1
2
4
3
LOAD CAPACITANCE (nF)
5
THRESHOLD VOLTAGE (V)
20
50
10–7
40
30
SINKING
VL = 5.5V
VL = 3.3V
VL = 1.8V
10
100
1000
DATA RATE (kbps)
SOURCING
20
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)
125
LTC2804 Driver Outputs
Enable/Disable
2V/DIV
MODE AND PS
100
2801 G12
2801 G11
2V/DIV
10000
Shutdown or Drivers Disabled Mode
Driver Leakage vs Temperature
10–8
LTC2804 Driver Outputs Exiting
Shutdown
TA = 85°C
TA = 25°C
TA = –40°C
INPUT HIGH
NORMAL
MODE
40
10–6
Logic Input Threshold
vs VL Supply Voltage
2.5
60
60
2801 G10
3.0
RECEIVERS
ALIVE MODE
2801 GO9
Driver Short-Circuit Current
vs Temperature
FALLING (LTC2802/04)
RISING (LTC2802/04)
FALLING (LTC2801/03)
RISING (LTC2801/03)
80
0
8
RIN = ±3V
CL = 150pF
2801 GO8
2801 GO7
80
7
LEAKAGE CURRENT (A)
0
–50 –25
0
100
VL = 5.5V
VL = 3.3V
VL = 1.8V
5
INPUT HIGH
OUTPUT VOLTAGE (V)
THRESHOLD VOLTAGE (V)
6
POSITIVE DUTY CYCLE (%)
3.0
TA = 25°C, VCC = VL = 3.3V unless otherwise noted.
MODE
2.0
1.5
T1OUT
5V/DIV
1.0
INPUT LOW
T1OUT
5V/DIV
T2OUT
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 + 250pF
2801 G14
2801 G15
2801234fe
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
PIN NAME
2803-1
2804-1 COMMENTS
Driver Input(s), referenced to VL.
RS-232 Driver Output(s).
RIN (R1IN, R2IN)
1
1, 2
1, 2
ROUT (R1OUT, R2OUT)
12
16, 15
16, 15
RS-232 Receiver Input(s). Includes internal 5kΩ termination resistor(s).
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, LTC2802, LTC2803, 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
RECEIVER(S) ACTIVE
L
H
ON
OFF
HI-Z
1µA
15µA
DRIVER(S) 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.
2801234fe
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
DFN-12
DFN-12
DFN-16
SSOP-16
DFN-16
SSOP-16
l
l
l
l
l
l
PACKAGE
1.8V - 5.5V OPERATION
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(S) 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
1Mb/s for RL = 3kΩ, CL = 250pF
l
l
l
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
2801 BD
GND
2801234fe
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
C2
1µF
VL
C5*
220nF
VCC
VL
EXTERNAL
DEVICE
RS-232
2801 F07
BOOST
REGULATOR
*OMIT IF VL IS CONNECTED TO VCC
Power-Saving Modes
When the DC-DC converter and drivers are turned off (PS
and MODE 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
CAP
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
VEE
2801 F06
C3
1µF
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).
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.
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.
2801234fe
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
Table 4. Recommended Ceramic Capacitor Manufacturers
GND
MANUFACTURER
URL
Murata
www.murata.com
TDK
www.tdk.com
Taiyo Yuden
www.t-yuden.com
AVX
www.avxcorp.com
Kemet
www.kemet.com
GND
C5
L1
VL
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
C2
GND
C5
VCC
GND
C4
CAP
GND
VCC
C2
1µF
L1
VL
C1
220nF
SW
C4
1µF
GND
C3
VDD
GND
TOP VIEW
= VIA
SCALE R1 WITH C1, C2, 1/C4
2801 F08
Figure 8. Supply Overshoot Protection for Input
Supplies of 4.5V or Higher
2801 F09
Figure 9. Recommended Board Layouts for (a) Single and
(b) Dual Transceiver Parts
2801234fe
11
LTC2801/LTC2802/
LTC2803/LTC2804
Typical Applications
1.8V TO 5.5V
5
12
LTC2803
VL
11
RA ON
5 VCC
VCC
1.8V TO 5.5V
CELL PHONE
MODE
10
LTC2804
12 VL
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
2801 F10
2801 F11
Figure 10. Power-Saving Receivers-Active Mode
5V
3V
3
1.8V
Figure 11. Cellphone Peripheral Interface
10
8
9
µP
VCC
VL
1.8V TO 5.5V
3
5V
LTC2801
10
8
PS
9
MODE
µP
TOUT 2
11 TIN
LTC2802
VL
MODE
OFF ON
TOUT 2
RIN 1
12 ROUT
GND
6
1.8V TO 5.5V
10
8
R T
9
VCC
VL
VCC
VL
11
6
ON/OFF
T2OUT 4
14 T1IN
T1OUT 3
15 R2OUT
R2IN 2
16 R1OUT
R1IN 1
GND
1.8V TO 5.5V
3
10
8
PS
MODE
R T
9
VCC
VL
8
2801 F13
Figure 13. 5V Microprocessor Interface
LTC2802
LTC2804-1
13 T2IN
GND
2801 F12
Figure 12. 1.8V Microprocessor Interface
3
12
PS
11 TIN
RIN 1
12 ROUT
5
VCC
Figure 14. Power-Saving Shutdown Mode
1.8V TO 5.5V
5
LTC2802
12
10
PS
R T
MODE
11
VCC
VL
LTC2803
PS
MODE
13 T2IN
TOUT 2
11 TIN
TOUT 2
11 TIN
RIN 1
GND
6
Figure 15. Half-Duplex on Single Line,
Separate ROUT, TIN
12
RIN 1
12 ROUT
3.3k 15 R2OUT
R2IN 2
6
T1OUT 3
3.3k 16 R1OUT
R1IN 1
GND
GND
2801 F15
T2OUT 4
14 T1IN
3.3k
12 ROUT
2801 F14
2801 F16
Figure 16. Half-Duplex on Single Line
8
2801 F17
Figure 17. Half-Duplex Dual Transceiver
2801234fe
LTC2801/LTC2802/
LTC2803/LTC2804
Typical Applications
2.5V TO 5.5V
5
13
4
14
3
12
C4
2µF
3k
CL
2801 F18
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
2801 F19
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
2801 F21
Figure 21. Typical SW Pin Waveforms
2801 F20
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)
2801234fe
13
LTC2801/LTC2802/
LTC2803/LTC2804
Package Description
DE/UE Package
12-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
0.70 p0.05
3.60 p0.05
2.20 p0.05
3.30 p0.05
1.70 p 0.05
PACKAGE OUTLINE
0.25 p 0.05
0.50 BSC
2.50 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
4.00 p0.10
(2 SIDES)
7
R = 0.115
TYP
0.40 p 0.10
12
R = 0.05
TYP
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
3.30 p0.10
3.00 p0.10
(2 SIDES)
1.70 p 0.10
0.75 p0.05
6
0.25 p 0.05
1
PIN 1 NOTCH
R = 0.20 OR
0.35 s 45o
CHAMFER
(UE12/DE12) DFN 0806 REV D
0.50 BSC
2.50 REF
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
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
2801234fe
14
LTC2801/LTC2802/
LTC2803/LTC2804
Package Description
DHC Package
16-Lead Plastic DFN (5mm × 3mm)
(Reference LTC DWG # 05-08-1706)
0.65 ±0.05
3.50 ±0.05
1.65 ±0.05
2.20 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
4.40 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
5.00 ±0.10
(2 SIDES)
R = 0.20
TYP
3.00 ±0.10
(2 SIDES)
9
R = 0.115
TYP
0.40 ± 0.10
16
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
PIN 1
NOTCH
0.200 REF
0.75 ±0.05
0.00 – 0.05
8
1
0.25 ± 0.05
0.50 BSC
(DHC16) DFN 1103
4.40 ±0.10
(2 SIDES)
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
2801234fe
15
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)
.0532 – .0688
(1.35 – 1.75)
2 3
4
5 6
7
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
2801234fe
16
LTC2801/LTC2802/
LTC2803/LTC2804
Revision History
(Revision history begins at Rev E)
REV
DATE
DESCRIPTION
PAGE NUMBER
E
5/10
Replaced Product Selection Guide
1
Labeled packages with appropriate part numbers in Pin Configuration section
2
Changed title of Table 1 in Mode Control section
8
Updated Feature Summary section
9
Revised first sentence of Power Saving Modes section
10
2801234fe
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.
17
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
11
PPX
PPY
µP
10
TXD
PPZ
RXD
VCC
7
9
SW
CAP
LTC2804
VL
PS
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
2801 F22
*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 Multidrop Applications
LTC1348
3-Driver/5-Receiver RS232 Transceiver
True RS232 Levels on 3.3V Supply
2801234fe
18 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 l FAX: (408) 434-0507
l
www.linear.com
LT 0510 REV E • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2005
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