Datasheet LTM8020 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | 200mA, 36V DC/DC µModule Regulator |
| Pages / Page | 16 / 7 — OPERATION. (1a) Continuous Operation. (1b) Burst Mode Operation. Figure … |
| File Format / Size | PDF / 406 Kb |
| Document Language | English |
OPERATION. (1a) Continuous Operation. (1b) Burst Mode Operation. Figure 1. Output Voltage and Internal Inductor Current
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LTM8020
OPERATION
The LTM8020 is a standalone nonisolated step-down The LTM8020 is built upon a variable frequency control- switching DC/DC power supply. It can deliver up to ler. The on time, off time and switching frequency are 200mA of DC output current with only bulk external input dependent upon the input voltage, output voltage and and output capacitors. This module provides a precisely load current. regulated output voltage programmable via one external The drive circuit for the internal power switching element resistor from 1.25VDC to 5VDC. The input voltage range is powered through the BIAS pin. Power this pin with at is 4V to 36V. Given that the LTM8020 is a step-down con- least 3V. verter, make sure that the input voltage is high enough to support the desired output voltage and load current. See The LTM8020 is equipped with two operating modes, Block Diagram. dependant upon the load current. When the load current is sufficiently high, the LTM8020 will switch continuously The LTM8020 contains a current mode controller, power (see Figure 1a). If the load is very light, or if the input switching element, power inductor, power Schottky diode voltage is high relative to the output voltage, the part will and a modest amount of input and output capacitance. operate in Burst Mode® operation, alternating between its For some applications, as shown in Table 1, no output micropower and switching states to keep the output in capacitor is necessary. regulation and hold the power dissipation to a minimum With its high performance current mode controller and (See Figure 1b). internal feedback loop compensation, the LTM8020 module If the SHDN pin is grounded, all internal circuits are turned has sufficient stability margin and good transient perfor- off and V mance under a wide range of operating conditions with a IN current reduces to the device leakage current, typically a few nanoamps. wide range of output capacitors, even all ceramic ones (X5R or X7R). Current mode control provides cycle-by-cycle fast current limit, and automatic current limiting protects the module in the event of a short circuit or overload fault. 200mA LOAD NO LOAD VOUT VOUT 20mV/DIV 20mV/DIV IL 100mA/DIV IL 100mA/DIV 1µs/DIV 1ms/DIV 150mA LOAD 10mA LOAD VOUT VOUT 20mV/DIV 20mV/DIV IL IL 100mA/DIV 100mA/DIV 1µs/DIV 8020 F1a 5µs/DIV 8020 F01b
(1a) Continuous Operation (1b) Burst Mode Operation Figure 1. Output Voltage and Internal Inductor Current
8020fe For more information www.linear.com/LTM8020 7
OPERATION
The LTM8020 is a standalone nonisolated step-down The LTM8020 is built upon a variable frequency control- switching DC/DC power supply. It can deliver up to ler. The on time, off time and switching frequency are 200mA of DC output current with only bulk external input dependent upon the input voltage, output voltage and and output capacitors. This module provides a precisely load current. regulated output voltage programmable via one external The drive circuit for the internal power switching element resistor from 1.25VDC to 5VDC. The input voltage range is powered through the BIAS pin. Power this pin with at is 4V to 36V. Given that the LTM8020 is a step-down con- least 3V. verter, make sure that the input voltage is high enough to support the desired output voltage and load current. See The LTM8020 is equipped with two operating modes, Block Diagram. dependant upon the load current. When the load current is sufficiently high, the LTM8020 will switch continuously The LTM8020 contains a current mode controller, power (see Figure 1a). If the load is very light, or if the input switching element, power inductor, power Schottky diode voltage is high relative to the output voltage, the part will and a modest amount of input and output capacitance. operate in Burst Mode® operation, alternating between its For some applications, as shown in Table 1, no output micropower and switching states to keep the output in capacitor is necessary. regulation and hold the power dissipation to a minimum With its high performance current mode controller and (See Figure 1b). internal feedback loop compensation, the LTM8020 module If the SHDN pin is grounded, all internal circuits are turned has sufficient stability margin and good transient perfor- off and V mance under a wide range of operating conditions with a IN current reduces to the device leakage current, typically a few nanoamps. wide range of output capacitors, even all ceramic ones (X5R or X7R). Current mode control provides cycle-by-cycle fast current limit, and automatic current limiting protects the module in the event of a short circuit or overload fault. 200mA LOAD NO LOAD VOUT VOUT 20mV/DIV 20mV/DIV IL 100mA/DIV IL 100mA/DIV 1µs/DIV 1ms/DIV 150mA LOAD 10mA LOAD VOUT VOUT 20mV/DIV 20mV/DIV IL IL 100mA/DIV 100mA/DIV 1µs/DIV 8020 F1a 5µs/DIV 8020 F01b
(1a) Continuous Operation (1b) Burst Mode Operation Figure 1. Output Voltage and Internal Inductor Current
8020fe For more information www.linear.com/LTM8020 7
