Datasheet LT1970 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | 500mA Power Op Amp with Adjustable Precision Current Limit |
| Pages / Page | 26 / 10 — block DiagraM anD TesT circuiT. applicaTions inForMaTion. Current Limit … |
| File Format / Size | PDF / 402 Kb |
| Document Language | English |
block DiagraM anD TesT circuiT. applicaTions inForMaTion. Current Limit Amplifiers. CIRCUIT DESCRIPTION
Model Line for this Datasheet
Text Version of Document
LT1970
block DiagraM anD TesT circuiT
RFB VCC 1k 7 V+ 19 15V +IN 9 + Q1 + V OUT IN – GM1 1× 3 –IN 8 – Q2 RG 1k 10k ISNK 17 10k – ISRC 16 D1 10k I + R SINK CS TSD VSNK – 15V 18 + 1Ω SENSE+ 4 ENABLE FILTER + 15 ENABLE VSRC 5 – VC SENSE– SNK 5V 12 VCSNK – 6 RFIL R D2 1k LOAD VC 1k SRC 13 I VC SRC V– SRC + 2 COMMON V 14 EE –15V 1, 10, 11, 20 1970TC
applicaTions inForMaTion
The LT1970 power op amp with precision controllable between –IN and +IN. No current will flow at the inputs current limit is a flexible voltage and current source when differential input voltage is present. This feature is module. The drawing on the front page of this data sheet important when the precision current sense amplifiers is representative of the basic application of the circuit, “ISINK” and “ISRC” become active. however many alternate uses are possible with proper understanding of the sub circuit capabilities.
Current Limit Amplifiers
Amplifier stages “ISINK” and “ISRC” are very high transcon-
CIRCUIT DESCRIPTION
ductance amplifier stages with independently controlled offset voltages. These amplifiers monitor the voltage be-
Main Operational Amplifier
tween input pins SENSE+ and SENSE– which usually sense Sub circuit block GM1, the 1X unity-gain current buffer the voltage across a small external current sense resistor. and output transistors Q1 and Q2 form a standard opera- The transconductance amplifiers outputs connect to the tional amplifier. This amplifier has ±500mA current output same high impedance node as the main input stage GM1 capability and a 3.6MHz gain bandwidth product. Most amplifier. Small voltage differences between SENSE+ and applications of the LT1970 will use this op amp in the main SENSE–, smaller than the user set VCSNK/10 and VCSRC/10 signal path. All conventional op amp circuit configurations in magnitude, cause the current limit amplifiers to decouple are supported. Inverting, noninverting, filter, summation from the signal path. This is functionally indicated by diodes or nonlinear circuits may be implemented in a conven- D1 and D2 in the Block Diagram. When the voltage VSENSE tional manner. The output stage includes current limiting increases in magnitude sufficient to equal or overcome one at ±800mA to protect against fault conditions. The input of the offset voltages VCSNK/10 or VCSRC/10, the appropri- stage has high differential breakdown of 36V minimum ate current limit amplifier becomes active and because of 1970fe 10 For more information www.linear.com/LT1970 Document Outline Description Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Package Description Related Parts
block DiagraM anD TesT circuiT
RFB VCC 1k 7 V+ 19 15V +IN 9 + Q1 + V OUT IN – GM1 1× 3 –IN 8 – Q2 RG 1k 10k ISNK 17 10k – ISRC 16 D1 10k I + R SINK CS TSD VSNK – 15V 18 + 1Ω SENSE+ 4 ENABLE FILTER + 15 ENABLE VSRC 5 – VC SENSE– SNK 5V 12 VCSNK – 6 RFIL R D2 1k LOAD VC 1k SRC 13 I VC SRC V– SRC + 2 COMMON V 14 EE –15V 1, 10, 11, 20 1970TC
applicaTions inForMaTion
The LT1970 power op amp with precision controllable between –IN and +IN. No current will flow at the inputs current limit is a flexible voltage and current source when differential input voltage is present. This feature is module. The drawing on the front page of this data sheet important when the precision current sense amplifiers is representative of the basic application of the circuit, “ISINK” and “ISRC” become active. however many alternate uses are possible with proper understanding of the sub circuit capabilities.
Current Limit Amplifiers
Amplifier stages “ISINK” and “ISRC” are very high transcon-
CIRCUIT DESCRIPTION
ductance amplifier stages with independently controlled offset voltages. These amplifiers monitor the voltage be-
Main Operational Amplifier
tween input pins SENSE+ and SENSE– which usually sense Sub circuit block GM1, the 1X unity-gain current buffer the voltage across a small external current sense resistor. and output transistors Q1 and Q2 form a standard opera- The transconductance amplifiers outputs connect to the tional amplifier. This amplifier has ±500mA current output same high impedance node as the main input stage GM1 capability and a 3.6MHz gain bandwidth product. Most amplifier. Small voltage differences between SENSE+ and applications of the LT1970 will use this op amp in the main SENSE–, smaller than the user set VCSNK/10 and VCSRC/10 signal path. All conventional op amp circuit configurations in magnitude, cause the current limit amplifiers to decouple are supported. Inverting, noninverting, filter, summation from the signal path. This is functionally indicated by diodes or nonlinear circuits may be implemented in a conven- D1 and D2 in the Block Diagram. When the voltage VSENSE tional manner. The output stage includes current limiting increases in magnitude sufficient to equal or overcome one at ±800mA to protect against fault conditions. The input of the offset voltages VCSNK/10 or VCSRC/10, the appropri- stage has high differential breakdown of 36V minimum ate current limit amplifier becomes active and because of 1970fe 10 For more information www.linear.com/LT1970 Document Outline Description Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Package Description Related Parts
