Datasheet LT1120A (Analog Devices) - 8
| 制造商 | Analog Devices |
| 描述 | Micropower Regulator with Comparator and Shutdown |
| 页数 / 页 | 14 / 8 — applicaTions inForMaTion. Frequency Compensation. Figure 1. Bypassing … |
| 文件格式/大小 | PDF / 196 Kb |
| 文件语言 | 英语 |
applicaTions inForMaTion. Frequency Compensation. Figure 1. Bypassing Reference. Increasing
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LT1120A
applicaTions inForMaTion
Other than placing large capacitive loads on the reference, affects the transient response; low output currents have no other precautions are necessary and the reference is long recovery times from load transients. At high operat- stable with nominal stray capacitances. ing temperatures the minimum load current increases and having too low of a load current may cause the output to go unregulated. Devices are tested for minimum load REF REF 6 6 current at high temperature. The output voltage setting OUTPUT 20Ω resistors to the feedback terminal can usually be used to 20Ω OR OUTPUT provide the minimum load current. + + 10µF 10µF 1120A F01
Frequency Compensation
The LT1120A is frequency compensated by a dominant
Figure 1. Bypassing Reference
pole on the output. An output capacitor of 10µF is usu- ally large enough to provide good stability.
Increasing the output capacitor above 10µF further improves sta- bility.
In order to ensure stability, a feedback capacitor
Overload Protection
is needed between the output pin and the feedback pin. The main regulator in the LT1120A is current limited at This is because stray capacitance can form another pole approximately 250mA. The current limit is stable with with the large value of feedback resistors used with the both input voltage and temperature. LT1120A. Also, a feedback capacitor minimizes noise pickup and improves ripple rejection. Like most other IC regulators, a minimum load is required on the output of the LT1120A to maintain regulation. For With the large dynamic operating range of the output most standard regulators this is normal y specified at current, 10000:1, frequency response changes widely. 5mA. Of course, for a micropower regulator this would be Low AC impedance capacitors are needed to insure a tremendously large current. The output current must be stability. While solid tantalum are best, aluminum elec- large enough to absorb all the leakage current of the pass trolytics can be used but larger capacitor values may be transistor at the maximum operating temperature. It also needed. 1120afb 8 For more information www.linear.com/LT1120A Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Typical Applications Package Description Revision History Related Parts
applicaTions inForMaTion
Other than placing large capacitive loads on the reference, affects the transient response; low output currents have no other precautions are necessary and the reference is long recovery times from load transients. At high operat- stable with nominal stray capacitances. ing temperatures the minimum load current increases and having too low of a load current may cause the output to go unregulated. Devices are tested for minimum load REF REF 6 6 current at high temperature. The output voltage setting OUTPUT 20Ω resistors to the feedback terminal can usually be used to 20Ω OR OUTPUT provide the minimum load current. + + 10µF 10µF 1120A F01
Frequency Compensation
The LT1120A is frequency compensated by a dominant
Figure 1. Bypassing Reference
pole on the output. An output capacitor of 10µF is usu- ally large enough to provide good stability.
Increasing the output capacitor above 10µF further improves sta- bility.
In order to ensure stability, a feedback capacitor
Overload Protection
is needed between the output pin and the feedback pin. The main regulator in the LT1120A is current limited at This is because stray capacitance can form another pole approximately 250mA. The current limit is stable with with the large value of feedback resistors used with the both input voltage and temperature. LT1120A. Also, a feedback capacitor minimizes noise pickup and improves ripple rejection. Like most other IC regulators, a minimum load is required on the output of the LT1120A to maintain regulation. For With the large dynamic operating range of the output most standard regulators this is normal y specified at current, 10000:1, frequency response changes widely. 5mA. Of course, for a micropower regulator this would be Low AC impedance capacitors are needed to insure a tremendously large current. The output current must be stability. While solid tantalum are best, aluminum elec- large enough to absorb all the leakage current of the pass trolytics can be used but larger capacitor values may be transistor at the maximum operating temperature. It also needed. 1120afb 8 For more information www.linear.com/LT1120A Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Typical Applications Package Description Revision History Related Parts