LT1794 LINER [Linear Technology], LT1794 Datasheet
LT1794
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LT1794 Summary of contents
Page 1
... Short-circuit protection and thermal shutdown insure the device’s ruggedness. The outputs drive a 100 supplies, and 10.9V with a 250mA load. The LT1794, with its increased swing on lower supplies, can be used to upgrade LT1795 line driver applications. The LT1794 is available in the very small, thermally enhanced, 20-lead TSSOP for maximum port density in line driver applications ...
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... C, JMAX = 0V 24.9k between V SHDNREF BIAS CONDITIONS f = 10kHz f = 10kHz + – – 2V 2V) CM Differential ORDER PART TOP VIEW NUMBER 20 NC LT1794CSW + 19 V LT1794ISW 18 OUT – – – – –IN 12 +IN 11 SHDNREF SW PACKAGE = 40 C/ C/W (Note ...
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... 5V –10, (Note 12V 10 1MHz 12V 10 1MHz 1MHz LT1794 = and SHDN unless otherwise noted. (Note 3) MIN TYP MAX – – 1 – – ...
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... Note 3: The LT1794C is guaranteed to meet specified performance from and is designed, characterized and expected to meet these extended temperature limits, but is not tested at – and 85 C. The LT1794I is guaranteed to meet the extended temperature limits ...
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... PER AMPLIFIER 0 –5 –10 –15 –20 1k 10k 100k 1M 100 FREQUENCY (Hz) 1794 G11 Supply Current vs V SHDN 12V SHDNREF 4.5 5.0 0 0.5 1.0 2.5 3.0 1.5 2.0 V (V) SHDN 1794 G14 LT1794 1794 G09 10M 100M 1794 G12 3.5 4.0 4.5 5.0 1794 G14 5 ...
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... LT1794 W U TYPICAL PERFOR A CE CHARACTERISTICS Differential Harmonic Distortion vs Output Amplitude – 1MHz – 12V –60 I PER AMPLIFIER = 10mA S –70 –80 –90 –100 OUT(P-P) Differential Harmonic Distortion vs Supply Current –40 –45 –50 – ...
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... The LT1794 is a high speed, 200MHz gain bandwidth product, dual voltage feedback amplifier with high output current drive capability, 500mA source and sink. The LT1794 is ideal for use as a line driver in xDSL data communication applications. The output voltage swing has been optimized to provide sufficient headroom when operating from 12V power supplies in full-rate ADSL applications ...
Page 8
... BIAS 100 130 150 170 190 BIAS Figure Ground Current Control BIAS , connected in one of BIAS connected be- BIAS + supply of the LT1794 connected between the BIAS + V – 1.2V • 25 BIAS + V – 1.2V • 25.6 – 2k 160 190 1794 F02 + V – 1.2V • ...
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... APPLICATIO S I FOR ATIO Logic Controlled Operating Current The DSP controller in a typical xDSL application can have I/O pins assigned to provide logic control of the LT1794 line driver operating current. As shown in Figure 4 one or two logic control inputs can control two or four different operating modes. The logic inputs add or subtract current to the SHDN input to set the operating current ...
Page 10
... The quiescent current for the LT1794 is set to 10mA per amplifier. The power dissipated in the LT1794 is a combination of the quiescent power and the output stage power when driving a signal. The two amplifiers are configured to place a differential signal on to the line ...
Page 11
... The junction temperature is determined from the following expression (W) • J AMBIENT D(FULL) is the thermal resistance from the junction of the JA LT1794 to the ambient air, which can be minimized –240 –200 W U heat-spreading PCB metal and airflow through the enclo- sure as required ...
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... VIAS USED: 32 EXAMPLE C/W JA 13MIL VIAS USED: 22 SCALE: 1 INCH Figure 8. Examples of PCB Metal Used for Heat Dissipation. LT1794IFE Driver Mounted on Top Layer. Heat Sink Pad Soldered to Top Layer Metal. External Components Mounted on Bottom Layer board produces a thermal resistance from junction to case, ...
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... In general, use feedback resistors less. Compensation The LT1794 is stable in a gain 10 or higher for any supply and resistive load easily compensated for lower gains with a single resistor or a resistor plus a capacitor. ...
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... LT1794 U U APPLICATIO S I FOR ATIO + – LOW FREQUENCIES BIG = Figure 12. Combination Compensation In differential driver applications, as shown on the first page of this data sheet recommended that the gain setting resistor be comprised of two equal value resistors connected to a good AC ground at high frequencies ...
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... With positive feedback, signals are present on both ends of the R Extra gain may be required in the receive channel to compensate completely separate receive path may be implemented through a separate line coupling transformer. A demo board, DC306A, is available for the LT1794. This /R )] demo board is a complete line driver with an LT1361 F P receiver included ...
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... While the LT1794 has clamps to the supply rails at the output pins, they may not be large enough to handle the significant transient energy. External clamping diodes, such as BAV99s, at each end of the transformer primary ® ...
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... PLIFIED SCHE ATIC + V –IN – V (one amplifier shown) Q9 Q10 Q12 Q11 Q13 Q17 C1 Q14 +IN OUT Q15 C2 Q18 Q16 1794 SS LT1794 17 ...
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... LT1794 PACKAGE DESCRIPTIO 6.60 0.10 4.50 0.10 SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.45 – 0.75 0.09 – 0.20 (.018 – .030) (.0036 – .0079) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE IN 3. DRAWING NOT TO SCALE 18 U Dimensions in inches (millimeters) unless otherwise noted. FE Package 20-Lead Plastic TSSOP (4.4mm) ...
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... DWG # 05-08-1620 NOTE 0.093 – 0.104 45 (2.362 – 2.642) 0 – 8 TYP 0.050 (1.270) BSC 0.014 – 0.019 (0.356 – 0.482) TYP LT1794 0.496 – 0.512* (12.598 – 13.005 0.394 – 0.419 (10.007 – 10.643 0.037 – ...
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... X8502-A OR EQUIVALENT – 1W DRIVER POWER DISSIPATION 13.7 1/2 1.15W POWER CONSUMPTION LT1794 SHDNREF + –12V COMMENTS 15V Operation, 1mV 360kHz, Differential Operation, 5V Supplies C Shutdown/Current Set Function, ADSL CO Driver Low Noise, Low Power Differential Receiver, 4mA/Amplifier 12V Operation, 7mA/Amplifier, ADSL Modem Line Driver ...