Datasheet LT3464 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | Micropower Boost Converter with Integrated Schottky and Output Disconnect in ThinSOT |
| Pages / Page | 16 / 8 — APPLICATIO S I FOR ATIO. Choosing an Inductor. Table 1. Recommended … |
| File Format / Size | PDF / 255 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Choosing an Inductor. Table 1. Recommended Inductors. PART NUMBER. DCR. CURRENT. MANUFACTURER. (mA)
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LT3464
U U W U APPLICATIO S I FOR ATIO Choosing an Inductor
in discontinuous mode. If the left hand side of inequality 1 The low current limit and fast switching of the LT3464 evaluates to less than tOFF, then use Equation 3 to calculate allow the use of very small surface mount inductors. The maximum output current. Otherwise, use Equation 2. minimum inductor size that may be used in a given This inequality is true when the LT3464 is operating in application depends on required efficiency and output discontinuous mode. current. Some inductors that work with the LT3464 are listed in Table 1, although there are many other manufac- LILIM turers and devices that can be used. Consult each manu- < t (INEQUALITY 1) V OFF ( OUT – VIN + V ) facturer for more detailed information and for their entire F selection of related parts. Many different sizes and shapes Use this equation to calculate the maximum output current are available. when the LT3464 is operating in continuous mode.
Table 1. Recommended Inductors
I
PART NUMBER
µ
H DCR CURRENT MANUFACTURER
OUT CM ( ) =
(
Ω
) (mA)
( LI 2 LIM + tOFF V ( IN – VOUT – VF V ))( IN – VCESAT) (2) LQH32CN680K53 68 2.2 130 Murata LQH32CN470K53 47 1.3 170 814-237-1431 L 2 V ( OUT – VCESAT + VF) LQH32CN220K53 22 0.71 250 www.murata.com ELJPC220KF 22 4.0 160 Panasonic Use this equation to calculate the maximum output current ELJPA470KF 47 2.25 135 714-373-7334 when the LT3464 is operating in discontinuous mode. www.panasonic.com CMD4D11-47 47 2.2 180 Sumida I = 847-956-0666 OUT DCM ( ) www.Sumida.com 2 LILIM V ( IN – V ) (3) LB2016-220 22 1.0 105 Taiyo Yuden CESAT LEM2520-220 22 5.5 125 408-573-4150 2 LI ( LIM + VIN tOFF – tOFF VCESAT)(–VIN + VOUT + VF) LEM2520-330 33 7.1 110 www.t-yuden.com LEMC2520-220 22 2.7 160 Where VF is the Schottky forward voltage, ILIM is the switch LEMC2520-330 33 4.8 120 current limit, t LEMF2520-220 22 1.2 105 OFF is the switch off time, and VCESAT is the LEMC3225-680 68 3.3 120 switch saturation voltage. See the Electrical Specifications. LEMC3225-101 100 4.3 100 Figures 1 through 3 show the worst-case maximum output current as given by Equations 2 and 3 using 20% inductor The following set of formulas can be used to calculate derating and worst-case LT3464 specifications. Also note maximum output current given V IN, VOUT and L values. that for some applications the maximum output current is Inequality 1 is used to determine if the LT3464 is operating limited to 25mA by the output disconnect circuitry. 25 25 17.5 15.0 20 L = 47µH 20 L = 47µH L = 47µH 12.5 L = 22µH L = 22µH 15 15 L = 22µH 10.0 (mA) (mA) (mA) L = 10µH 7.5 L = 10µH I OUT 10 I OUT 10 L = 10µH I OUT 5.0 5 5 2.5 L = 4.7µH L = 4.7µH L = 4.7µH 0 0 0 10 15 20 25 30 35 15 20 25 30 35 10 15 20 25 30 35 V V OUT (V) OUT (V) 3464 F02 3464 F03 VOUT (V) 3464 F01
Figure 3. Maximum Output Current Figure 1. Maximum Output Current Figure 2. Maximum Output Current VIN = 8.4V V V IN = 3.6V IN = 5V
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U U W U APPLICATIO S I FOR ATIO Choosing an Inductor
in discontinuous mode. If the left hand side of inequality 1 The low current limit and fast switching of the LT3464 evaluates to less than tOFF, then use Equation 3 to calculate allow the use of very small surface mount inductors. The maximum output current. Otherwise, use Equation 2. minimum inductor size that may be used in a given This inequality is true when the LT3464 is operating in application depends on required efficiency and output discontinuous mode. current. Some inductors that work with the LT3464 are listed in Table 1, although there are many other manufac- LILIM turers and devices that can be used. Consult each manu- < t (INEQUALITY 1) V OFF ( OUT – VIN + V ) facturer for more detailed information and for their entire F selection of related parts. Many different sizes and shapes Use this equation to calculate the maximum output current are available. when the LT3464 is operating in continuous mode.
Table 1. Recommended Inductors
I
PART NUMBER
µ
H DCR CURRENT MANUFACTURER
OUT CM ( ) =
(
Ω
) (mA)
( LI 2 LIM + tOFF V ( IN – VOUT – VF V ))( IN – VCESAT) (2) LQH32CN680K53 68 2.2 130 Murata LQH32CN470K53 47 1.3 170 814-237-1431 L 2 V ( OUT – VCESAT + VF) LQH32CN220K53 22 0.71 250 www.murata.com ELJPC220KF 22 4.0 160 Panasonic Use this equation to calculate the maximum output current ELJPA470KF 47 2.25 135 714-373-7334 when the LT3464 is operating in discontinuous mode. www.panasonic.com CMD4D11-47 47 2.2 180 Sumida I = 847-956-0666 OUT DCM ( ) www.Sumida.com 2 LILIM V ( IN – V ) (3) LB2016-220 22 1.0 105 Taiyo Yuden CESAT LEM2520-220 22 5.5 125 408-573-4150 2 LI ( LIM + VIN tOFF – tOFF VCESAT)(–VIN + VOUT + VF) LEM2520-330 33 7.1 110 www.t-yuden.com LEMC2520-220 22 2.7 160 Where VF is the Schottky forward voltage, ILIM is the switch LEMC2520-330 33 4.8 120 current limit, t LEMF2520-220 22 1.2 105 OFF is the switch off time, and VCESAT is the LEMC3225-680 68 3.3 120 switch saturation voltage. See the Electrical Specifications. LEMC3225-101 100 4.3 100 Figures 1 through 3 show the worst-case maximum output current as given by Equations 2 and 3 using 20% inductor The following set of formulas can be used to calculate derating and worst-case LT3464 specifications. Also note maximum output current given V IN, VOUT and L values. that for some applications the maximum output current is Inequality 1 is used to determine if the LT3464 is operating limited to 25mA by the output disconnect circuitry. 25 25 17.5 15.0 20 L = 47µH 20 L = 47µH L = 47µH 12.5 L = 22µH L = 22µH 15 15 L = 22µH 10.0 (mA) (mA) (mA) L = 10µH 7.5 L = 10µH I OUT 10 I OUT 10 L = 10µH I OUT 5.0 5 5 2.5 L = 4.7µH L = 4.7µH L = 4.7µH 0 0 0 10 15 20 25 30 35 15 20 25 30 35 10 15 20 25 30 35 V V OUT (V) OUT (V) 3464 F02 3464 F03 VOUT (V) 3464 F01
Figure 3. Maximum Output Current Figure 1. Maximum Output Current Figure 2. Maximum Output Current VIN = 8.4V V V IN = 3.6V IN = 5V
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