LM2596-ADJ Calculator – Feedback Resistors, Inductor E·T, Min VIN

Answer

VOUT = 1.23 V × (1 + R2/R1), with R1 between 240 Ω and 1.5 kΩ on TI parts. For 5 V with R1 = 1 kΩ, R2 = 3.09 kΩ gives 5.03 V. Pick the inductor from E·T = (VIN − VOUT − VSAT) × (VOUT + VD) / (VIN − VSAT + VD) × 1000 / 150 kHz (V·µs). Source: TI LM2596 SNVS124G, §9.2.2.2, p.28.

Calculator

VIN min (V) VIN max (V) VOUT (V) IOUT (A) R1 (Ω) Series Chip

R2 exact: 3.065 kΩ
R2 nearest: 3.09 kΩ
VOUT at nearest R2: 5.031 V
VOUT band (VFB 1.193–1.267 V): 4.879 V – 5.182 V
Inductor E·T: 18.9 V·µs
Duty: 0.488
Switch conduction loss: 1.697 W
VIN,min at 25 °C: 6.40 V
VIN,min full temperature: 6.50 V
IOUT: 3 A

VD = 0.5 V is an assumption. The onsemi full-temperature figure (about 7.29 V for 5 V out, Vsat ≈ 2.0 V) uses the typical 95% max duty cycle and is not a guaranteed worst-case VIN,min.

pass R1 recommended range: TI LM2596 recommends R1 240–1500 Ω.
pass Input operating range: VIN,max = 12 V. Fail above 40 V operating (abs max 45 V).
pass Minimum input at 25 °C: 25 °C VIN,min ≈ 6.40 V (max VSAT 1.4 V, Dmax 1).
pass Minimum input over temperature: Full-temperature estimate ≈ 6.50 V (max VSAT 1.5 V). VD = 0.5 V is an assumption.

How it works

Feedback is the same shape on TI, onsemi and XL2596 parts: VOUT = 1.23 × (1 + R2/R1). R1 = 1 kΩ sits inside both TI’s 240 Ω–1.5 kΩ range and onsemi’s 1–5 kΩ range. The output band uses VFB 1.193–1.267 V.

Inductor E·T follows TI equation (8) with VD = 0.5 V. A printed “+0.05 V” in equation (9) does not reproduce TI’s own 28 V to 20 V example of 34.2 V·µs. With VD = 0.5 V that example is 34.19 V·µs.

Switch conduction loss here is only an estimate: P ≈ D × IOUT × VSAT, with D = (VOUT + VD) / (VIN − VSAT + VD).

Minimum input for 5 V out

VD = 0.5 V is an assumption. The formula is VIN,min = (VOUT + VD) / Dmax + VSAT − VD, using maximum VSAT.

Maker	25 °C	Full temperature range
TI	6.4 V (Vsat 1.4 V)	6.5 V (Vsat 1.5 V)
XL2596	6.5 V (Vsat 1.5 V)	not specified (Ta = 25 °C data only)
onsemi	7.09 V (Vsat 1.8 V)	about 7.29 V (Vsat ≈ 2.0 V)

The onsemi full-temperature figure (about 7.29 V, Vsat ≈ 2.0 V) uses the typical 95% max duty cycle because onsemi gives no minimum. It is not a guaranteed worst-case VIN,min. Leave extra margin. “7 V in, 5 V out” is below both onsemi estimates.

Inductor E·T (V·µs)

At VSAT 1.16 / 1.3 / 1.5 V (TI typical / XL2596 typical / onsemi typical):

Conversion	E·T
12 V to 5 V	18.9 / 18.7 / 18.3
24 V to 12 V	38.7 / 38.4 / 38.0
24 V to 5 V	28.0 / 28.0 / 27.9
12 V to 3.3 V	16.8 / 16.7 / 16.6

The three chips differ by less than 3%, so the same inductor choice works for all of them. Conduction loss at 12 V to 5 V and 3 A (typical VSAT) is about 1.69 W (TI), 1.92 W (XL2596) and 2.25 W (onsemi).

Part numbers

Maker	Part	Package
TI	LM2596S-ADJ / LM2596T-ADJ	TO-263 / TO-220
onsemi	LM2596TADJG / LM2596DSADJR4G	TO-220 / D2PAK
XLSEMI	XL2596S-ADJE1 / XL2596T-ADJE1	TO263-5L / TO220-5L

Confirm the exact suffixes in each maker’s ordering table. Cross-maker notes are on the LM2596 equivalents page.

Disclaimer

Values come from the manufacturer datasheets above, as read on 26 Oct 2026. Loss and minimum-input figures are estimates derived from datasheet equations. Modules sold as “LM2596” may use parts from any of these makers, or others. Check the datasheet for the exact part on the board and test under worst-case input and load.

Updated: 2026-10-26 · Jasper

Parameters used on this page

Parameter	Value	Source
Operating VIN / absolute maximum	TI, onsemi and XL2596: 4.5–40 V operating / 45 V absolute maximum	TI §7.3 and §7.1; onsemi Maximum Ratings; XL2596
VFB	1.193–1.267 V (typ 1.23 V)	TI p.6; onsemi Electrical Characteristics; XL2596 Electrical Characteristics
Oscillator at 25 °C	TI 127/150/173 kHz; onsemi 135/150/165 kHz; XL2596 127/150/173 kHz	TI p.7; onsemi; XL2596 (Ta = 25 °C only)
Oscillator over temperature	TI 110–173 kHz; onsemi 120–180 kHz; XL2596 not specified beyond 25 °C	TI p.7; onsemi
Switch saturation at 3 A	TI 1.16 typ / 1.4 V max at 25 °C, 1.5 V max full temperature; onsemi 1.5 typ / 1.8 V max at 25 °C, 2.0 V max full temperature; XL2596 1.3 typ / 1.5 V max at 25 °C only	TI p.7; onsemi; XL2596
Max duty cycle	TI 100%; onsemi 95% typical only; XL2596 100%	TI p.7; onsemi; XL2596
Current limit	TI 3.6/4.5/6.9 A; onsemi 4.2/5.6/6.9 A; XL2596 3.6/4.8/6.9 A	Datasheet electrical tables
ON/OFF (EN)	TI on at or below 0.6 V, off at or above 2.0 V; onsemi VIL 1.0 V, VIH 2.2 V at 25 °C; XL2596 0.8 / 1.4 V typical, floating = on	TI p.7; onsemi; XL2596
Recommended R1	TI 240 Ω–1.5 kΩ; onsemi 1–5 kΩ; XL2596 about 1 kΩ	TI p.28; onsemi; XL2596
Operating TJ and RθJA	−40 to 125 °C. TI TO-220 50 °C/W; onsemi TO-220 65 °C/W, D2PAK 70 °C/W; XL2596 30 °C/W on the maker's board	TI §7.4 and p.5; onsemi; XL2596

Worked examples

R1 = 1 kΩ and 5 V: exact R2 is 3.065 kΩ, and 3.09 kΩ gives 5.031 V. 12 V uses 8.66 kΩ (11.882 V), 3.3 V uses 1.69 kΩ (3.309 V), and 9 V uses 6.34 kΩ (9.028 V). Minimum input for 5 V out, using max VSAT and VD = 0.5 V: TI 6.4 V at 25 °C and 6.5 V over the full temperature range; XL2596 6.5 V at 25 °C (full temperature not specified); onsemi 7.09 V at 25 °C and about 7.29 V over the full temperature range (Vsat ≈ 2.0 V). The onsemi 7.29 V figure uses the typical 95% max duty cycle and is not a guaranteed worst-case VIN,min.

Pitfalls

R1 range differs by maker. onsemi recommends 1–5 kΩ and TI recommends 240 Ω–1.5 kΩ. The LM317 value of 240 Ω is outside onsemi's range. 1 kΩ suits both.
ON/OFF is active-low. TI: at or below 0.6 V on, at or above 2.0 V off. onsemi: 1.0 / 2.2 V at 25 °C. XL2596 publishes typical thresholds only (0.8 / 1.4 V) and is on when EN floats.
Minimum input depends on the maker. onsemi needs the most headroom: about 7.29 V full temperature for 5 V out (Vsat ≈ 2.0 V, 95% typical max duty, not a guaranteed worst case, VD = 0.5 V assumed).
A misprint in TI's E·T example. Equation (9) prints +0.05 V in the denominator. Only VD = 0.5 V reproduces TI's 34.2 V·µs example (28 V to 20 V is 34.19 V·µs).
Frequency tolerance differs. At 25 °C, TI is 127–173 kHz and onsemi is 135–165 kHz. Over temperature, TI is 110–173 kHz and onsemi is 120–180 kHz.

FAQ

What resistor values give 5 V on an LM2596?

R1 = 1 kΩ with R2 = 3.09 kΩ gives 5.031 V typical.

What is the LM2596 output voltage formula?

VOUT = 1.23 V × (1 + R2/R1).

What is the minimum input voltage for 5 V out?

About 6.4 V for TI at 25 °C and 6.5 V over the full temperature range, 6.5 V for XL2596 at 25 °C, and 7.09 V / about 7.29 V for onsemi at 25 °C / full temperature (Vsat 1.8 V / about 2.0 V). Figures assume VD = 0.5 V. onsemi uses a typical 95% max duty cycle, which is not a guaranteed worst case.

What inductor does the LM2596 need at 3 A?

Calculate E·T (for example 18.9 V·µs for 12 V to 5 V at TI's typical VSAT) and read the inductor value off TI's selection chart for 3 A.

Can I run an LM2596 at 7 V in and 5 V out?

On TI and XL2596 parts, yes with a little margin. On onsemi parts, 7 V is below the about 7.29 V full-temperature estimate (typical duty, not a guaranteed worst case), so plan for more input.

Is the ON/OFF pin active low?

Yes. Pull it low, or to GND, to run and high to shut down.

Sources

TI LM2596 SNVS124G: https://www.ti.com/lit/ds/symlink/lm2596.pdf (retrieved 2026-10-26).
onsemi LM2596/D Rev 1: https://www.onsemi.com/pdf/datasheet/lm2596-d.pdf (sections cited by name).
XLSEMI XL2596: http://www.xlsemi.com/datasheet/XL2596-EN.pdf (no revision code printed).
Updated: 2026-10-26. Jasper.