LTC2847 Linear Technology, LTC2847 Datasheet
LTC2847
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LTC2847 Summary of contents
Page 1
... The V face circuitry including the receiver output drivers. It can be tied to V interface with low voltage ASICs. The LTC2847 is available in a 0.8mm tall, 5mm 7mm QFN package. U Complete DTE or DCE Multiprotocol Serial Interface with DB-25 Connector ...
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... Short-Circuit Duration Transmitter Output ..................................... Indefinite Receiver Output .......................................... Indefinite V .................................................................. 30 sec EE Operating Temperature Range LTC2847C ............................................... LTC2847I ........................................... – Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER Supplies ...
Page 3
... GND OUT V and V 0.25V, Power Off No-Cable Mode or Driver Disabled (Figures 2, 13) (Figures 2, 13) (Figures 2, 13) – t (Figures 2, 13) PLH PHL (Figures 2, 13) LTC2847 MIN TYP MAX UNITS – 9.6 V – 7.5 – 8.5 V – 5.5 – 6.5 V – 4.5 – 6.0 V 500 kHz ...
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... LTC2847 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER V.11 Receiver V Input Threshold Voltage TH V Input Hysteresis TH R Input Impedance Rise or Fall Time Input to Output Rising PLH t Input to Output Falling PHL t Input to Output Difference, t V.35 Driver V Differential Output Voltage ...
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... DATA RATE (kBd) 2846 G05 V.28 Mode I vs Temperature CC 37.5 37.0 36.5 36.0 35.5 35.0 34.5 34.0 33 100 – –40 20 TEMPERATURE ( C) 2846 G08 LTC2847 MAX UNITS 0 0 300 ns 300 VCC VIN 100 2846 G06 100 3846 G09 sn2847 2847fs ...
Page 6
... LTC2847 CTIO S NC (Pins 1,3,18,19,22,23): No Connect. V (Pin 2): Generated Positive Supply Voltage for DD V.28. Connect capacitor to ground. V (Pin 4): Input Supply Pin. Input supply to charge CC pump and transceiver. 4.75V capacitor to GND. D1 (Pin 5): TTL Level Driver 1 Input. D2 (Pin 6): TTL Level Driver 2 Input. ...
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... 10k M0 11 MODE 20k M1 12 SELECTION LOGIC – GND D3/ 51 125 51.5 24 D3/ 51.5 S2 125 51 51.5 S2 125 51 2847 BD LTC2847 sn2847 2847fs 7 ...
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... LTC2847 TEST CIRCUITS Figure 1. V.11 Driver DC Test Circuit – CM Figure 3. Input Impedance Test Circuit 125 Figure 5. V.35 Driver Open-Circuit Test 50 50 125 50 50 2847 F08 Figure 8. V.35 Driver AC Test Circuit Figure 11. V.28 Driver Test Circuit 8 4 DataSheet U .com ...
Page 9
... PHL 90% 50% 10 SKEW INPUT 0V t PHL OUTPUT 1.65V LTC2847 (Note 4) (Note 5) 9.3V –6V 9.3V –6V 9.3V –6V 9.3V –6V 8V –6.5V 9.3V –6V 8.7V –8.5V Z 4.7V 0.3V 9.3V –6V 9.3V –6V 9.3V –6V 9.3V –6V 8V –6.5V 9.3V –6V 8.7V –8.5V Z 4.7V 0. with LTC2847 with LTC2847 A 2847 F13 2847 F14 sn2847 2847fs 9 ...
Page 10
... Cable termination is provided on-chip, elimi- nating the need for discrete termination designs. A complete DCE-to-DTE interface operating in EIA530 mode is shown in Figure 17. The LTC2847 half of each port is used to generate and appropriately terminate the clock and data signals. The LTC2845 is used to generate ...
Page 11
... LTC2847/LTC2845 will enter no-cable mode. In this mode the LTC2847/LTC2845 supply current drops to less than 1000 A and the LTC2847/LTC2845 driver outputs are forced into a high impedance state. At the same time, the R2 and R3 receivers of the LTC2847 are differentially terminated with 103 and the other receiv- 4 DataSheet U .com ...
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... Alternatively, custom cables may contain termination in the cable head or route signals to various terminations on the board. The LTC2847/LTC2845 chip set solves the cable termina- tion switching problem by automatically providing the appropriate termination and switching on-chip for the V.10 (RS423), V.11 (RS422), V.28 (RS232) and V.35 electrical protocols ...
Page 13
... In V.11 mode, all switches are off except S1 of the LTC2847’s receivers which connects a 103 differential 1 Actually, there is no switch S1 in receivers R2 and R3. However, for simplicity, all termination networks on the LTC2847 can be treated identically assumed that an S1 switch exists and is always closed on the R2 and R3 receivers. 4 DataSheet U .com ...
Page 14
... DataSheet U .com V.35 mode, both switches S1 and S2 inside the LTC2847 are on, connecting a T network impedance as shown in Figure 27. The 30k input impedance of the receiver is placed in parallel with the T network termination, but does not affect the overall input impedance significantly. The generator differential impedance must be 50 ...
Page 15
... DTE or DCE operation. For example, in DTE mode, the TXD signal is routed to Pins 2 and 14 via the LTC2847’s Driver 1. In DCE mode, Driver 1 now routes the RXD signal to Pins 2 and 14. Power Dissipation Calculations The LTC2847 takes ...
Page 16
... SCTE TXC RXC RXD Figure 29. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector 16 4 DataSheet U .com CHARGE 1 F PUMP C4 3 LTC2847 DCE/DTE 3. GND DD C8 ...
Page 17
... RTS C10 M1 D4ENB DCE/DTE NC R4EN Figure 30. Controller-Selectable DCE Port with DB-25 Connector LTC2847 2 RXD A (104) 14 RXD B 24 RXC A (115) 11 RXC B 15 TXC A (114) 12 TXC B 24 SCTE A (113) 11 SCTE B 2 TXD A (103) 14 TXD B 7 SGND (102) ...
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... CC 5V DTE_TXD/DCE_RXD DTE_SCTE/DCE_RXC DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD DCE/DTE Figure 31. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector 18 4 DataSheet U .com CHARGE 1 F PUMP LTC2847 DCE/DTE GND DTE_RTS/DCE_CTS ...
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... ON THE TOP AND BOTTOM OF PACKAGE 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. LTC2847 0.70 0.05 PACKAGE OUTLINE 3 ...
Page 20
... V . Assume AC power dissipation can be assumed to be equal to the power dissipation. The extra power dissipated in the LTC2847 due to LTC2845 is given by Equation(4 43% • (5.5V • 23mA) = 55mW. So for an X.21 DCE port = RT running at 10MBd, the LTC2847 dissipates approximately 718mW + 55mW = 773mW while the LTC2845 dissipates = 5V • ...