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LTC2801/LTC2802/ LTC2803/LTC2804 1.8V to 5.5V RS-232 Single and Dual Transceivers FEATURES

DESCRIPTIO

PRODUCT SELECTIO 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 SSOP 16-Lead DFN 16-Lead SSOP
APPLICATIO S

Battery-Powered Systems Computers and Consumer Electronics Diagnostic Ports
, LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
1.8V TO 5.5V L1 10H C4 1F VCC VL PS OFF ON MODE TIN LTC2802
LTC2802 at 1.8V and 1Mbps
SW C1 220nF CAP
2V/DIV
TIN
5V/DIV TOUT
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
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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
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.
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2801 TA01b
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2801234f
1
LTC2801/LTC2802/ LTC2803/LTC2804 ABSOLUTE
(Note 1)
AXI U RATI GS
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
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
PACKAGE/ORDER I FOR ATIO
1-Driver/1-Receiver
TOP VIEW RIN TOUT VCC VDD SW GND 1 2 3 4 5 6 13 12 ROUT 11 TIN 10 VL 9 MODE 8 PS 7 CAP
2-Driver/2-Receiver
TOP VIEW R1IN R2IN T1OUT T2OUT VCC VDD SW GND 1 2 3 4 5 6 7 8 17 16 R1OUT 15 R2OUT 14 T1IN 13 T2IN 12 VL 11 MODE 10 PS 9 CAP
DE PACKAGE 12-LEAD (4mm x 3mm) PLASTIC DFN TJMAX = 125C, JA = 43C/W, JC = 4.3C/W (4 Layer) EXPOSED PAD IS VEE (PIN 13) MUST BE SOLDERED TO PCB
DHC PACKAGE 16-LEAD (5mm x 3mm) PLASTIC DFN TJMAX = 125C, JA = 44C/W, JC = 4.3C/W (4 Layer) EXPOSED PAD IS VEE (PIN 17) MUST BE SOLDERED TO PCB
ORDER PART NUMBER LTC2801CDE LTC2801IDE LTC2802CDE LTC2802IDE
DE PART* MARKING 2801 2801 2802 2802
ORDER PART NUMBER LTC2803CDHC LTC2803IDHC LTC2804CDHC LTC2804IDHC
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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2-Driver/2-Receiver
TOP VIEW R1IN 1 R2IN 2 T1OUT 3 T2OUT 4 VCC 5 VDD 6 SW 7 GND 8 16 R1OUT 15 R2OUT 14 T1IN 13 T2IN 12 VL 11 ON/OFF 10 CAP 9 VEE
GN PACKAGE 16-LEAD PLASTIC SSOP TJMAX = 125C, JA = 110C/W, JC = 40C/W (4 Layer)
DHC PART* MARKING 2803 2803 2804 2804
ORDER PART NUMBER LTC2803CGN-1 LTC2803IGN-1 LTC2804CGN-1 LTC2804IGN-1
GN PART MARKING 28031 2803I1 28041 2804I1
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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 Low High Low High VL = VCC = 5.5V; VTOUT = 0V VL = VCC = VDD = VEE = 0V; VTOUT = 2V Shutdown or Receivers Active or Drivers Disabled Modes, -15V VTOUT 15V 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 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 2.3 1 1 0.08 0.15 15 1 -5 5 0.4 0.67 * VL 0.6

The 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

10 10 0.15 0.30 30 10
mA A A mA mA A A V V V V V mA A A
IL
VL Supply Current
Driver VOLD VOHD VILD VIHD VHYSD IOSD IPOLD IOLD Receiver VIR VILR VIHR VHYSR VOLR VOHR RIN IOSR VDD Input Thresholds

Output Voltage Logic Input Voltage Threshold Logic Input Hysteresis Output Short Circuit Current Power-Off Output Leakage Current Output Leakage Current

-5.7 6.2
35 0.1 0.1
70 10 10
0.8 0.8 0.1
1.5 1.3 1.7 0.4
2.4 2.5 1.0 0.4 7 50
V V V V V V k mA
Input Hysteresis Output Voltage Input Resistance Output Short Circuit Current Regulated VDD Output Voltage
0.2 VL -0.4 VL -0.2 3 5 25
Power Supply Generator 7 V
VEE
Regulated VEE Output Voltage
-6.3
V
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LTC2801/LTC2802/ LTC2803/LTC2804
The 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.
SYMBOL PARAMETER Maximum Data Rate 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)

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
0.2 50 60 5 0.15
0.4
s ns
200 15 0.3
ns s s
Power Supply Generator VDD/VEE Supply Rise Time
0.2
2
ms
Note 1: Absolute maximum ratings are those beyond which the life of a device may be impaired. 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 t THL TOUT SR(D) = 6V tTHL or tTLH 3V -3V 3V -3V t TLH VOHD VOLD
2801F02
VL 0V
TIN
RL
CL
TIN tr, tf 40ns
Figure 1. Driver Slew Rate Measurement
TOUT TIN TIN RL CL TOUT 1/2 VL t PHLD 0V tSKEWD = |tPHLD - tPLHD| TIN tr, tf 40ns 1/2 VL
VL 0V t PLHD VOHD 0V VOLD
2801F02
Figure 2. Driver Timing Measurement
ROUT
RIN
3V 1.5V t PHLR 1.5V -3V t PLHR 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 t PZHD 1/2 VL 0V t PHZD 5V t PZLD t PLZD 0V -5V VOLD + 0.5V VOLD VOHD - 0.5V VOHD 0V
0 OR VL RL
TOUT TOUT MODE CL TOUT MODE tr, tf 40ns
2801F04
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 t PZLR 1/2 VL VL 1/2 VL t PZHR 1/2 VL t PLZR VL VOLR + 0.5V VOLR
2801F05
1/2 VL 0V t PHZR VOHR - 0.5V VOHR 0V
Figure 5. Receiver Enable/Disable Times
TYPICAL PERFOR A CE 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
SUPPLY CURRENT (mA)
VCC = VL = 1.8V 2s/DIV WRAPPING DATA TOUT LOAD = 1nF + RIN ROUT LOAD = 150pF
Supply Current vs Supply Voltage (Dual Transceiver)
60 50 SUPPLY CURRENT (mA) 40 125kbps 30 20 10 LTC2804 LTC2803 0 0 1 2 3 4 5 SUPPLY VOLTAGE (V) 6
2801 G04
SUPPLY CURRENT (mA)
1nF 1nF 60 250pF 40 250pF LTC2804 LTC2802 0 200 600 400 DATA RATE (kbps) 800 1000
2801 G05
SUPPLY CURRENT (mA)
ALL DRIVERS SWITCHING VCC = VL RL = 3k 250kbps CL = 1nF
20.8kbps
6
UW
2801 G01
TA = 25C, VCC = VL = 3.3V unless otherwise noted.
LTC2804 at 1.8V and 1Mbps
3.0 T1IN 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 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 Data Rate
100 ALL DRIVERS SWITCHING VCC = VL = 1.8V RL = 3k 100
Supply Current vs Load Capacitance (Dual Transceiver)
250kbps 80 125kbps
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
0
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LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Input Threshold vs Temperature (C)
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 OUTPUT VOLTAGE (V) INPUT HIGH 6 5 4 3 2 1 0
POSITIVE DUTY CYCLE (%)
50 25 75 0 TEMPERATURE (C)
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
SHORT-CIRCUIT CURRENT (mA)
SINKING 40 30 20 10 REGULATOR CAN LIMIT FURTHER 0 -50 -25 50 25 75 0 TEMPERATURE (C) 100 125 SOURCING
LEAKAGE CURRENT (A)
FALLING (LTC2802/04) RISING (LTC2802/04) FALLING (LTC2801/03) RISING (LTC2801/03)
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
1
2
3 4 5 VL SUPPLY VOLTAGE (V)
UW
100
2801 GO7
TA = 25C, VCC = VL = 3.3V unless otherwise noted.
Receiver Output Voltage vs Load Current
VL = 5.5V VL = 3.3V VL = 1.8V 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
125
2801 GO8
Driver Short-Circuit Current vs Temperature (C)
60 50 10-6 10-7 10-8 10-9
Shutdown or Drivers Disabled Mode Driver Leakage vs Temperature (C)
V(TOUT) = 15V OR V(TOUT) = -15V
10-10 10-11 -50 -25
50 25 75 0 TEMPERATURE (C)
100
125
2801 G11
2801 G12
LTC2804 Driver Outputs Exiting Shutdown
LTC2804 Driver Outputs Enable/Disable
2V/DIV
MODE AND PS
2V/DIV
MODE
T1OUT 5V/DIV T2OUT
T1OUT T2OUT
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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 PI FU CTIO S
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.
ODE CO TROL
PS L L H H MODE L H L H RECEIVER OUTPUT(S) HIGH-Z ON ON ON DC-DC OFF OFF ON ON DRIVER OUTPUT(S) HIGH-Z HIGH-Z HIGH-Z ON IVCC* 1A 1A 2.1mA 2.3mA IVL* 1A 15A 80A OR 150A 80A OR 150A
Table 1. LTC2801-LTC2804
MODE NAME SHUTDOWN RECEIVERS ACTIVE DRIVERS DISABLED NORMAL
Table 2. LTC2803-1, LTC2804-1
MODE NAME SHUTDOWN NORMAL ON/OFF L H RECEIVER OUTPUTS HIGH-Z ON DC-DC OFF ON DRIVER OUTPUTS HIGH-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 SU
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
BLOCK DIAGRA
1.8V TO 5.5V
1.8V TO 5.5V C5 220nF
**
**
LTC2801 LTC2802 LTC2803 LTC2804 LTC2803-1 LTC2804-1
W
WW
ARY
2801 1+1 DE

2802 1+1 DE

2803 2+2 DHC

2803-1 2+2 GN

2804 2+2 DHC

2804-1 2+2 GN

L1 10H C4 1F VCC SW
C1 220nF CAP VDD
VL BOOST REGULATOR
VEE C3 1F C2 1F
VL T2IN T1IN
VDD T2OUT T1OUT VL
**
R2OUT
GND
VEE
R2IN
**
5k R1OUT VL PS MODE ON/OFF GND CONTROL 5k ** LTC2803 LTC2804 LTC2803-1 LTC2804-1 R1IN
GND
2801BD
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LTC2801/LTC2802/ LTC2803/LTC2804 APPLICATIO S I FOR ATIO
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
*OMIT IF VL IS CONNECTED TO VCC
2801F06
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).
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ANY VOLTAGE FROM 1.8V TO 5.5V ANY VOLTAGE FROM 1.8V TO 5.5V VCC VL EXTERNAL DEVICE RS-232
2801F07
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UU
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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LTC2801/LTC2802/ LTC2803/LTC2804 APPLICATIO S I FOR ATIO
Table 3. Recommended Inductors
PART NUMBER LQH2MCN100K02L LBC2016T100K FSLB2520-100K ISAT (mA) 225 245 220 MAX DCR () 1.2 0.85 1.1 SIZE (mm) MANUFACTURER 2x1.6x0.95 Murata www.murata.com 2x1.6x1.6 Taiyo Yuden www.t-yuden.com 2.5x2x1.6 Toko www.tokoam.com
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
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 L1 10H C1 220nF
R1 1 1/8W C4 1F
SW
C2 1F SCALE R1 WITH C1, C2, 1/C4
VDD
Figure 8. Supply Overshoot Protection for Input Supplies of 4.5V or Higher
U
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).
C1 GND GND C2 VL GND C5 VCC GND C4 L1 GND TOP VIEW = VIA C3 C1 GND GND C2 VL GND C5 VCC GND C4 L1
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CAP
GND C3
GND
TOP VIEW = VIA
2801F08
2801F09
Figure 9. Recommended Board Layouts for (a) Single and (b) Dual Transceiver Parts
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LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIO S
1.8V TO 5.5V 5 12 11 10 VCC LTC2803 VL MODE PS T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 GND 8
2801F10
RA ON
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
1.8V
12 ROUT GND 6
RIN 1
2801F12
Figure 12. 1.8V Microprocessor Interface
1.8V TO 5.5V 3 10 8 RT 9 VCC LTC2802 VL PS MODE
11 TIN
TOUT 2 3.3k
12 ROUT GND 6
RIN 1
2801F15
Figure 15. Half-Duplex on Single Line, Separate ROUT, TIN
12
U
5 VCC 1.8V TO 5.5V 12 VL 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
Figure 11. Cellphone Peripheral Interface
1.8V TO 5.5V 5 12 VCC LTC2804-1 VL
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
2801F13
RIN 1
16 R1OUT
8
2801F14
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 15 R2OUT 14 T1IN 12 ROUT GND 6
2801F16
RIN 1
3.3k 16 R1OUT
8
2801F17
Figure 16. Half-Duplex on Single Line
Figure 17. Half-Duplex Dual Transceiver
2801234f
LTC2801/LTC2802/ LTC2803/LTC2804 TYPICAL APPLICATIO S
2.5V TO 5.5V L1 10H
13
4
14
3 3k CL
2801F18
DATA RATE CL (nF) LTC2803 LTC2804 (kbps) X X 5 100 X X 2 250 X 0.5 1000
Figure 18. Driving Larger Loads
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
VDD 6
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)
U
5 C4 2F 12
VCC LTC2803 VL
SW CAP
7 9 C1 470nF
5 12
VCC LTC2803 VL
SW CAP
7 9
13 T2IN 14 T1IN 15 R2OUT 16 R1OUT GND 8 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
2801F19
C2 2F
C3 2F
ANY COMBINATION LTC2801/LTC2802/LTC2803/LTC2804
Figure 19. Quad Transceiver (2.5V < VCC < 5.5V)
PS T2IN T1IN VEE 17
10 13 14
VCC = 5.5V DRIVERS LOADED 200ns/DIV
2801F21
Figure 21. Typical SW Pin Waveforms
2801234f
13
LTC2801/LTC2802/ LTC2803/LTC2804 PACKAGE DESCRIPTIO U
DE/UE Package 12-Lead Plastic DFN (4mm x 3mm)
(Reference LTC DWG # 05-08-1695)
4.00 0.10 (2 SIDES) 0.65 0.05 R = 0.20 TYP 3.00 0.10 (2 SIDES) 1.70 0.10 (2 SIDES) PIN 1 NOTCH
(UE12/DE12) DFN 0603
7
R = 0.115 TYP
0.38 0.10 12
3.50 0.05 1.70 0.05 2.20 0.05 (2 SIDES)
PIN 1 TOP MARK (NOTE 6) PACKAGE OUTLINE 0.25 0.05 3.30 0.05 (2 SIDES) 0.50 BSC 0.200 REF
0.75 0.05
6 0.25 0.05 3.30 0.10 (2 SIDES)
1 0.50 BSC
0.00 - 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
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
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 3.50 0.05 R = 0.20 TYP R = 0.115 TYP 9 16 0.40 0.10
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
2801234f
14
LTC2801/LTC2802/ LTC2803/LTC2804 PACKAGE DESCRIPTIO U
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 .150 - .165 .229 - .244 (5.817 - 6.198) .0165 .0015 .150 - .157** (3.810 - 3.988) .0250 BSC 1 .015 .004 x 45 (0.38 0.10)
.007 - .0098 (0.178 - 0.249) 0 - 8 TYP
.254 MIN
RECOMMENDED SOLDER PAD LAYOUT 23 4 56 7 8 .004 - .0098 (0.102 - 0.249)
.0532 - .0688 (1.35 - 1.75)
.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
2801234f
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 APPLICATIO U
1.8V TO 5.5V L1 10H C4 1F * DC-DC 1.8V TO 5.5V C5 220nF * VCC CTS RD P RTS TD 11 13 14 15 16 5 12 10 PS MODE T2IN T1IN R2OUT R1OUT T2OUT 4 T1OUT 3 R2IN 2 R1IN 1 CTS RD UART RTS TD VCC VL 7 SW 9 CAP C1 220nF LTC2804 GND 8 VDD 6 C2 1F *ADDITIONAL BYPASS CAP AS NEEDED VEE 17 C3 1F
2801F22
+ -
Figure 22. Diagnostic Port Operating Directly Off Unregulated Battery Voltage
RELATED PARTS
PART NUMBER LT1780/LT1781 LTC1337 LTC1338 LTC1348 DESCRIPTION 2-Driver/2-Receiver RS232 Transceiver 3-Driver/5-Receiver RS232 Transceiver 5-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
LT1039/LT1039-16 3-Driver/3-Receiver RS232 Transceiver
2801234f
16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT/TP 0305 500 * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005

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