Datasheet LT3503 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | 1A, 2.2MHz Step-Down Switching Regulator in 2mm x 3mm DFN |
| Pages / Page | 20 / 10 — APPLICATIO S I FOR ATIO. Table 1. Inductor Vendors. Vendor. URL. Part … |
| File Format / Size | PDF / 438 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Table 1. Inductor Vendors. Vendor. URL. Part Series. Inductance Range (. Size (mm). Catch Diode
Model Line for this Datasheet
Text Version of Document
LT3503
U U W U APPLICATIO S I FOR ATIO Table 1. Inductor Vendors Vendor URL Part Series Inductance Range (
µ
H) Size (mm)
Sumida www.sumida.com CDRH4D28 1.2 to 4.7 4.5 × 4.5 CDRH5D28 2.5 to 10 5.5 × 5.5 CDRH8D28 2.5 to 33 8.3 × 8.3 Toko www.toko.com A916CY 2 to 12 6.3 × 6.2 D585LC 1.1 to 39 8.1 × 8.0 Würth Elektronik www.we-online.com WE-TPC(M) 1 to 10 4.8 × 4.8 WE-PD2(M) 2.2 to 22 5.2 × 5.8 WE-PD(S) 1 to 27 7.3 × 7.3 transient response. If your load is lower than 1A, then you impedance, or there is significant inductance due to long can decrease the value of the inductor and operate with wires or cables, additional bulk capacitance may be nec- higher ripple current. This allows you to use a physically essary. This can be provided with a low performance smaller inductor, or one with a lower DCR resulting in electrolytic capacitor. higher efficiency. There are several graphs in the Typical Step-down regulators draw current from the input supply Performance Characteristics section of this data sheet that in pulses with very fast rise and fall times. The input show the maximum load current as a function of input capacitor is required to reduce the resulting voltage ripple voltage and inductor value for several popular output at the LT3503 and to force this very high frequency voltages. Low inductance may result in discontinuous switching current into a tight local loop, minimizing EMI. mode operation, which is okay, but further reduces maxi- A 1µF capacitor is capable of this task, but only if it is mum load current. For details of the maximum output placed close to the LT3503 and the catch diode; see the current and discontinuous mode operation, see Linear PCB Layout section. A second precaution regarding the Technology Application Note 44. ceramic input capacitor concerns the maximum input voltage rating of the LT3503. A ceramic input capacitor
Catch Diode
combined with trace or cable inductance forms a high Depending on load current, a 1A to 2A Schottky diode is quality (underdamped) tank circuit. If the LT3503 circuit is recommended for the catch diode, D1. The diode must plugged into a live supply, the input voltage can ring to have a reverse voltage rating equal to or greater than the twice its nominal value, possibly exceeding the LT3503’s maximum input voltage. The ON Semiconductor MBRM140 voltage rating. This situation is easily avoided; see the Hot is a good choice; it is rated for 1A continuous forward Plugging Safely section. current and a maximum reverse voltage of 40V.
Output Capacitor Input Capacitor
The output capacitor has two essential functions. Along Bypass the input of the LT3503 circuit with a 1µF or higher with the inductor, it filters the square wave generated by value ceramic capacitor of X7R or X5R type. Y5V types the LT3503 to produce the DC output. In this role it have poor performance over temperature and applied determines the output ripple so low impedance at the voltage and should not be used. A 1µF ceramic is adequate switching frequency is important. The second function is to bypass the LT3503 and will easily handle the ripple to store energy in order to satisfy transient loads and current. However, if the input power source has high stabilize the LT3503’s control loop. 3503f 10
U U W U APPLICATIO S I FOR ATIO Table 1. Inductor Vendors Vendor URL Part Series Inductance Range (
µ
H) Size (mm)
Sumida www.sumida.com CDRH4D28 1.2 to 4.7 4.5 × 4.5 CDRH5D28 2.5 to 10 5.5 × 5.5 CDRH8D28 2.5 to 33 8.3 × 8.3 Toko www.toko.com A916CY 2 to 12 6.3 × 6.2 D585LC 1.1 to 39 8.1 × 8.0 Würth Elektronik www.we-online.com WE-TPC(M) 1 to 10 4.8 × 4.8 WE-PD2(M) 2.2 to 22 5.2 × 5.8 WE-PD(S) 1 to 27 7.3 × 7.3 transient response. If your load is lower than 1A, then you impedance, or there is significant inductance due to long can decrease the value of the inductor and operate with wires or cables, additional bulk capacitance may be nec- higher ripple current. This allows you to use a physically essary. This can be provided with a low performance smaller inductor, or one with a lower DCR resulting in electrolytic capacitor. higher efficiency. There are several graphs in the Typical Step-down regulators draw current from the input supply Performance Characteristics section of this data sheet that in pulses with very fast rise and fall times. The input show the maximum load current as a function of input capacitor is required to reduce the resulting voltage ripple voltage and inductor value for several popular output at the LT3503 and to force this very high frequency voltages. Low inductance may result in discontinuous switching current into a tight local loop, minimizing EMI. mode operation, which is okay, but further reduces maxi- A 1µF capacitor is capable of this task, but only if it is mum load current. For details of the maximum output placed close to the LT3503 and the catch diode; see the current and discontinuous mode operation, see Linear PCB Layout section. A second precaution regarding the Technology Application Note 44. ceramic input capacitor concerns the maximum input voltage rating of the LT3503. A ceramic input capacitor
Catch Diode
combined with trace or cable inductance forms a high Depending on load current, a 1A to 2A Schottky diode is quality (underdamped) tank circuit. If the LT3503 circuit is recommended for the catch diode, D1. The diode must plugged into a live supply, the input voltage can ring to have a reverse voltage rating equal to or greater than the twice its nominal value, possibly exceeding the LT3503’s maximum input voltage. The ON Semiconductor MBRM140 voltage rating. This situation is easily avoided; see the Hot is a good choice; it is rated for 1A continuous forward Plugging Safely section. current and a maximum reverse voltage of 40V.
Output Capacitor Input Capacitor
The output capacitor has two essential functions. Along Bypass the input of the LT3503 circuit with a 1µF or higher with the inductor, it filters the square wave generated by value ceramic capacitor of X7R or X5R type. Y5V types the LT3503 to produce the DC output. In this role it have poor performance over temperature and applied determines the output ripple so low impedance at the voltage and should not be used. A 1µF ceramic is adequate switching frequency is important. The second function is to bypass the LT3503 and will easily handle the ripple to store energy in order to satisfy transient loads and current. However, if the input power source has high stabilize the LT3503’s control loop. 3503f 10
