Answer: The LM2596TADJG is onsemi’s adjustable 3 A, 150 kHz buck regulator in a 5-lead TO-220 (Pb-free, 50 per tube). It keeps the LM2596 pinout and 1.23 V feedback, but its switch drops more: 1.8 V max at 25 °C and 2.0 V over temperature at 3 A, with a 95 % typical maximum duty cycle. For 5 V out at 3 A, that puts the minimum input at about 7.29 V over temperature. (onsemi LM2596/D Rev. 1, pp.2, 4, 23.)
Key specifications
| Parameter | Value | Condition | Source |
|---|---|---|---|
| Feedback voltage | 1.193 / 1.23 / 1.267 V; 1.18–1.28 V over temperature | VIN 8.5–40 V, ILOAD 0.5–3 A, VOUT 5 V | Electrical Characteristics, p.4 |
| Saturation voltage | 1.5 typ / 1.8 max V; 2.0 V max over temperature | IOUT = 3 A | p.4 |
| Max duty cycle (ON) | 95 % (typical; no minimum given) | Feedback at 0 V | p.4 |
| Current limit (peak) | 4.2 / 5.6 / 6.9 A; 3.5–7.5 A over temperature | — | p.4 |
| Oscillator frequency | 135 / 150 / 165 kHz; 120–180 kHz over temperature | — | p.4 |
| Quiescent current | 5.0 typ / 10 max mA | Switch forced off | p.4 |
| Standby current | 80 typ / 200 max µA; 250 µA over temperature | ON/OFF = 5 V, VIN = 40 V | p.4 |
| ON/OFF thresholds | OFF ≥ 2.2 V (2.4 V over temp); ON ≤ 1.0 V (0.8 V over temp); 1.6 V typ | — | p.4 |
| ON/OFF pin voltage | −0.3 V to +VIN | Maximum rating | p.2 |
| Input voltage | 4.5–40 V operating; 45 V max | — | pp.2–3 |
| Thermal resistance, TO-220 | RθJA 65 °C/W; RθJC 5.0 °C/W | Case 314B / 314D | Maximum Ratings, p.2 |
| Recommended R1 | 1.0–5.0 kΩ | Adjustable output | pp.7, 9 |
| Operating junction temperature | −40 to +125 °C (150 °C max) | — | pp.2–3 |
Pinout and tab
Pin 1 VIN, 2 Output, 3 Ground, 4 Feedback, 5 ON/OFF (p.1, p.3), the same order as TI’s part. onsemi states that the heatsink surface is connected to pin 3 (ground) (p.1), so a grounded heat sink needs no insulator for this package.
Minimum input voltage: the 7.29 V number
With the switch drop at its maximum and the duty cycle at 95 %, for 5 V out at 3 A (diode drop VD = 0.5 V assumed):
VIN,min ≈ (VOUT + VD) / Dmax + VSAT − VD
| Condition | VSAT used | VIN,min |
|---|---|---|
| 25 °C | 1.8 V | ≈ 7.09 V |
| Full temperature | 2.0 V | ≈ 7.29 V |
| TI LM2596 for comparison (100 % duty) | 1.4 / 1.5 V | ≈ 6.4 / 6.5 V |
onsemi gives the 95 % only as a typical value, so 7.29 V is an estimate, not a guaranteed worst case. Leave margin, and remember that the feedback accuracy row itself is specified from 8.5 V input for a 5 V output (p.4).
Heat
At 12 V to 5 V and 3 A, with the typical 1.5 V drop: duty ≈ (5 + 0.5)/(12 − 1.5 + 0.5) = 0.50, switch loss ≈ 1.5 × 3 × 0.50 = 2.25 W, about 2.31 W with quiescent current. That is roughly 0.56 W more than a TI part in the same circuit.
- Free-standing at 65 °C/W: 2.31 × 65 ≈ 150 °C rise. A heat sink is mandatory.
- onsemi’s method (p.17): TJ = PD × (RθJC + RθCS + RθSA) + TA. For TJ ≤ 125 °C at 40 °C ambient, the total must stay below 85 / 2.31 ≈ 36.8 °C/W. Subtract RθJC (5 °C/W), and the interface plus heat sink must be ≤ about 31.8 °C/W.
Design notes
- Divider. VOUT = 1.23 V × (1 + R2/R1) with R1 between 1.0 and 5.0 kΩ (p.7, p.9). R1 = 1 kΩ, R2 = 3.09 kΩ → 5.03 V; the same values work on TI parts (TI’s R1 range is 240 Ω–1.5 kΩ).
- ON/OFF. Pulling above about 1.6 V shuts it down; open or low runs it (p.3). Guaranteed levels are tighter than TI’s at the low end (≤ 0.8 V over temperature to run) and accept up to +VIN.
- Fold-back. On an overload that drops the output about 40 %, the oscillator falls to about 30 kHz to cut dissipation (p.4, note 2).
Pitfalls specific to onsemi LM2596TADJG
- Expecting TI’s dropout from a 7 V rail. For 5 V out at 3 A the onsemi part needs about 7.09 V at 25 °C and 7.29 V over temperature (VSAT ≈ 2.0 V, 95 % typical duty, VD = 0.5 V assumed). This is not a guaranteed worst case; leave extra margin.
- Reusing a TI heat sink sized for 50 °C/W free-standing. onsemi’s free-standing figure is 65 °C/W and the switch loss is higher.
- Mixing the T and TV codes. LM2596TADJG is TO-220 (case 314D); LM2596TVADJG is “TO-220 (F)” (case 314B), a different lead form. Check the outline drawing before swapping them.
- Copying the TI R1 range. onsemi recommends 1–5 kΩ; 1 kΩ suits both.
Part numbers (information only)
| onsemi orderable | Package | Shipping |
|---|---|---|
| LM2596TADJG | TO-220, 5 lead (case 314D) | 50 / tube |
| LM2596TVADJG | TO-220 (F), 5 lead (case 314B) | 50 / tube |
| LM2596DSADJG | D2PAK | 50 / tube |
| LM2596DSADJR4G | D2PAK | 800 / tape and reel |
Source: Ordering Information, p.23. Marking on the TO-220: “LM 2596T−ADJ AWLYWWG” (p.1). All are Pb-free; MSL 1 (p.1).
FAQ
- Is onsemi LM2596TADJG a drop-in for TI LM2596T-ADJ? Same pinout and 1.23 V feedback, so it fits the footprint, but it needs more input headroom (about 7.29 V for 5 V/3 A over temperature) and dissipates more.
- What is the tab of the LM2596TADJG connected to? Pin 3, ground (p.1).
- What does the G suffix mean? Pb-free package, per onsemi’s marking legend (p.1).
- What R1 does onsemi recommend? 1.0 to 5.0 kΩ. 1 kΩ also fits TI’s 240 Ω–1.5 kΩ range.
- Why does my onsemi-based module drop out at 7 V input? With 2.0 V maximum switch drop over temperature and 95 % typical duty, 5 V at 3 A needs about 7.29 V in.
Related (internal links)
- LM2596 equivalents: TI vs onsemi vs XL2596
- LM2596-ADJ calculator
- TI LM2596T-ADJ
- XLSEMI XL2596S-ADJE1
- Buck converters
Sources (retrieved 2026-10-26)
- onsemi, LM2596 3.0 A Step-Down Switching Regulator, LM2596/D Rev. 1 (December 2022): https://www.onsemi.com/pdf/datasheet/lm2596-d.pdf
- For comparison only: Texas Instruments, LM2596 SIMPLE SWITCHER Power Converter 150-kHz 3-A Step-Down Voltage Regulator, SNVS124G (revised March 2023), including the Package Option Addendum: https://www.ti.com/lit/ds/symlink/lm2596.pdf
Disclaimer
Values are copied from onsemi LM2596/D Rev. 1, read on 26 Oct 2026. Minimum-input and heat figures are our arithmetic with a 0.5 V diode drop assumed; the 95 % duty cycle is typical only. Verify against the current datasheet and test on your board.
Reviewed by: Jasper · Updated: 2026-10-26