Datasheet LT1610 (Analog Devices) - 9
| Hersteller | Analog Devices |
| Beschreibung | 1.7MHz, Single Cell Micropower DC/DC Converter |
| Seiten / Seite | 16 / 9 — APPLICATIONS INFORMATION. Figure 6. 4-Cell Alkaline to 5V/120mA SEPIC … |
| Dateiformat / Größe | PDF / 224 Kb |
| Dokumentensprache | Englisch |
APPLICATIONS INFORMATION. Figure 6. 4-Cell Alkaline to 5V/120mA SEPIC DC/DC Converter. All Ceramic, Low Profile Design
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LT1610
U U W U APPLICATIONS INFORMATION
C3 1µF L1 CERAMIC 22µH D1 V • OUT 5V 120mA 6 5 1M • VIN SW L2 + 1 2 C1 22 C4 V µH C FB 4 CELLS 22µF 1µF LT1610 + C2 C5 6.3V CERAMIC 324k 22 8 µF 1µF 3 COMP SHDN 6.3V CERAMIC GND PGND 7 4 C1, C2: ALUMINUM ELECTROLYTIC 1610 F06 C3 TO C5: CERAMIC X7R OR X5R SHUTDOWN D1: MBR0520 L1, L2: MURATA LQH3C220 OR SUMIDA CLS62-220
Figure 6. 4-Cell Alkaline to 5V/120mA SEPIC DC/DC Converter
sation network is modified to achieve stable operation. VOUT 200mV/DIV Linear Technology’s Application Note 19 contains a de- tailed description of the method. A good starting point for IDIODE the LT1610 is C 500mA/DIV C ~ 220pF and RC ~ 220k. SWITCH
All Ceramic, Low Profile Design
VOLTAGE 10V/DIV Large value ceramic capacitors that are suitable for use as 100ns/DIV 1610 F07 the main output capacitor of an LT1610 regulator are now
Figure 7. Switching Waveforms Without Ceramic Capacitor C5
available. These capacitors have very low ESR and there- fore offer very low output ripple in a small package. V However, you should approach their use with some OUT 50mV/DIV caution. IDIODE Ceramic capacitors are manufactured using a number of 500mA/DIV dielectrics, each with different behavior across tempera- SWITCH ture and applied voltage. Y5V is a common dielectric used VOLTAGE 10V/DIV for high value capacitors, but it can lose more than 80% of the original capacitance with applied voltage and extreme VIN = 4.1V 100ns/DIV 1610 F08 LOAD = 100mA temperatures. The transient behavior and loop stability of
Figure 8. Switching Waveforms with Ceramic Capacitor C5.
the switching regulator depend on the value of the output
Note the 50mV/DIV Scale for VOUT
capacitor, so you may not be able to afford this loss. Other dielectrics (X7R and X5R) result in more stable character- It is best to choose the compensation components empiri- istics and are suitable for use as the output capacitor. The cally. Once the power components have been chosen X7R type has better stability across temperature, whereas (based on size, efficiency, cost and space requirements), the X5R is less expensive and is available in higher values. a working circuit is built using conservative (or merely guessed) values of RC and CC. Then the response of the The second concern in using ceramic capacitors is that circuit is observed under a transient load, and the compen- many switching regulators benefit from the ESR of the 9
U U W U APPLICATIONS INFORMATION
C3 1µF L1 CERAMIC 22µH D1 V • OUT 5V 120mA 6 5 1M • VIN SW L2 + 1 2 C1 22 C4 V µH C FB 4 CELLS 22µF 1µF LT1610 + C2 C5 6.3V CERAMIC 324k 22 8 µF 1µF 3 COMP SHDN 6.3V CERAMIC GND PGND 7 4 C1, C2: ALUMINUM ELECTROLYTIC 1610 F06 C3 TO C5: CERAMIC X7R OR X5R SHUTDOWN D1: MBR0520 L1, L2: MURATA LQH3C220 OR SUMIDA CLS62-220
Figure 6. 4-Cell Alkaline to 5V/120mA SEPIC DC/DC Converter
sation network is modified to achieve stable operation. VOUT 200mV/DIV Linear Technology’s Application Note 19 contains a de- tailed description of the method. A good starting point for IDIODE the LT1610 is C 500mA/DIV C ~ 220pF and RC ~ 220k. SWITCH
All Ceramic, Low Profile Design
VOLTAGE 10V/DIV Large value ceramic capacitors that are suitable for use as 100ns/DIV 1610 F07 the main output capacitor of an LT1610 regulator are now
Figure 7. Switching Waveforms Without Ceramic Capacitor C5
available. These capacitors have very low ESR and there- fore offer very low output ripple in a small package. V However, you should approach their use with some OUT 50mV/DIV caution. IDIODE Ceramic capacitors are manufactured using a number of 500mA/DIV dielectrics, each with different behavior across tempera- SWITCH ture and applied voltage. Y5V is a common dielectric used VOLTAGE 10V/DIV for high value capacitors, but it can lose more than 80% of the original capacitance with applied voltage and extreme VIN = 4.1V 100ns/DIV 1610 F08 LOAD = 100mA temperatures. The transient behavior and loop stability of
Figure 8. Switching Waveforms with Ceramic Capacitor C5.
the switching regulator depend on the value of the output
Note the 50mV/DIV Scale for VOUT
capacitor, so you may not be able to afford this loss. Other dielectrics (X7R and X5R) result in more stable character- It is best to choose the compensation components empiri- istics and are suitable for use as the output capacitor. The cally. Once the power components have been chosen X7R type has better stability across temperature, whereas (based on size, efficiency, cost and space requirements), the X5R is less expensive and is available in higher values. a working circuit is built using conservative (or merely guessed) values of RC and CC. Then the response of the The second concern in using ceramic capacitors is that circuit is observed under a transient load, and the compen- many switching regulators benefit from the ESR of the 9