Answer: The XL2596S-ADJE1 is XLSEMI’s adjustable 3 A, 150 kHz buck regulator in TO263-5L, supplied 800 per reel. It follows the LM2596 pinout (VIN, SW, GND, FB, EN) with a 1.193–1.267 V feedback window and a 1.5 V max switch drop at 3 A. Two gaps matter in design: every limit is specified at Ta = 25 °C only, and the EN pin has typical thresholds only (0.8 V on, 1.4 V off). (XLSEMI XL2596 Rev 2.7, pp.2, 4, 6, 7; checked against a mirror copy.)
Key specifications
| Parameter | Value | Condition | Source |
|---|---|---|---|
| Feedback voltage | 1.193 / 1.23 / 1.267 V | VIN 4.5–40 V, ILOAD 0.2–3 A, Ta 25 °C | XL2596-ADJ Electrical Characteristics, p.6 |
| Input voltage | 4.5–40 V operating; −0.3 to 45 V abs. max | — | pp.5, 7 |
| Output saturation voltage | 1.3 typ / 1.5 max V | IOUT = 3 A, VFB = 0 V | p.7 |
| Max duty cycle | 100 % (typical) | VFB = 0 V | p.7 |
| Switch current limit | 3.6 / 4.8 / 6.9 A | VFB = 0 V | p.7 |
| Oscillator frequency | 127 / 150 / 173 kHz | — | p.7 |
| EN threshold | 1.4 V (off) / 0.8 V (on), typical only | No min/max given | p.7 |
| EN input current | 5 typ / 15 max µA (EN 2.5 V); 0.2 typ / 5 max µA (EN 0.5 V) | — | p.7 |
| Shutdown supply current | 80 typ / 200 max µA | VEN = 5 V | p.7 |
| Quiescent supply current | 2 typ / 10 max mA | VEN = 0 V, VFB = VIN | p.7 |
| Thermal resistance | RθJA 30 °C/W | “No heatsink, free air”; same figure for TO220-5L and TO263-5L | Absolute Maximum Ratings, p.5 |
| Operating junction temperature | −40 to +125 °C | — | p.5 |
Pinout (TO263-5L)
Pin 1 VIN, 2 SW, 3 GND, 4 FB, 5 EN, with the metal tab on GND (Figure 2 and Table 1, p.2). The functions match TI’s LM2596 (VIN, Output, Ground, Feedback, ON/OFF), only the names differ.
Specified at 25 °C only
Every electrical table in the XL2596 datasheet carries the condition Ta = 25 °C (pp.6–7). There are no over-temperature limits for feedback voltage, saturation, current limit or frequency. TI’s LM2596 gives both (for example, 1.18–1.28 V feedback over −40 to 125 °C). If your design depends on accuracy or headroom when hot, measure it, or use the TI numbers as a guide and label them as such.
EN pin: typical values only
The EN thresholds are typical only (0.8 V on, 1.4 V off), with no guaranteed minimum or maximum (p.7). The pin floats low, so the part runs when EN is open (Table 1, p.2), and EN is rated −0.3 V to VIN (p.5).
- Drive EN firmly: tie it to GND to run, and ≥ 3.3 V (or VIN) to shut down.
- Don’t drive it from a slow RC or a mid-level divider, and don’t rely on a 1.8 V GPIO to turn it off.
Setting the output
VOUT = 1.23 V × (1 + R2/R1), with R1 around 1 kΩ, 1 % (p.8). Above about 10 V out, XLSEMI requires a feed-forward capacitor across R2, typically 100 pF–33 nF, from CFF = 1 / (31 × 10³ × R2) (p.8):
| Target | R1 / R2 | VOUT (nominal) | CFF from formula |
|---|---|---|---|
| 5 V | 1 kΩ / 3.09 kΩ | 5.03 V | ≈ 10 nF (optional below 10 V) |
| 12 V | 1 kΩ / 8.87 kΩ | 12.14 V | ≈ 3.6 nF (required) |
XLSEMI does not recommend Z5U ceramics for CFF (p.8).
Headroom and heat
For 5 V out at 3 A with the 1.5 V maximum drop and 100 % duty, the input must be at least about 6.5 V at 25 °C. That is 0.1 V more than TI’s 6.4 V. Over temperature, the datasheet gives no figure.
At 12 V to 5 V and 3 A with the typical 1.3 V drop: duty ≈ 5.5 / 11.2 = 0.49, switch loss ≈ 1.3 × 3 × 0.49 ≈ 1.92 W. XLSEMI’s 30 °C/W “no heatsink, free air” figure would give a 58 °C rise. That figure is much lower than TI’s own 50 °C/W free-standing TO-220 or 0.5 in² TO-263 numbers, and XLSEMI does not state a board. Treat it as optimistic and size the copper as you would for the TI LM2596S-ADJ.
Pitfalls specific to XL2596S-ADJE1
- Treating XL2596 as identical to TI’s LM2596. Its EN pin only has typical thresholds, so do not drive it from a weak or mid-level signal.
- Borrowing TI’s over-temperature limits. XLSEMI publishes 25 °C limits only.
- Designing to the 30 °C/W figure. It carries no board description; use measured board temperatures.
- Dropping “E1” or the “S”. E1 marks the Pb-free (RoHS) version; S is TO263-5L and T is TO220-5L (p.4).
Part numbers (information only)
| XLSEMI order code | Package | Packing |
|---|---|---|
| XL2596S-ADJE1 | TO263-5L | 800 / tape and reel |
| XL2596T-ADJE1 | TO220-5L | not stated |
| XL2596S-3.3E1 / -5.0E1 / -12E1 | TO263-5L, fixed outputs | 800 / tape and reel |
Source: Ordering Information, p.4. The marking ID is the same as the order code.
FAQ
- Is XL2596 the same as LM2596? Same pinout, feedback voltage, frequency and input range. The switch drop is slightly higher, every limit is at 25 °C only, and the EN thresholds are typical only.
- Does the XL2596 run with EN left open? Yes. EN floats low, which turns the regulator on (Table 1, p.2).
- What voltage turns the XL2596 off? The typical threshold is 1.4 V, but no maximum is guaranteed. Drive EN to 3.3 V or higher.
- What is the tab connected to? GND (Figure 2, p.2).
- What does E1 mean in XL2596S-ADJE1? Pb-free, RoHS-compliant (p.4).
Related (internal links)
- LM2596 equivalents: TI vs onsemi vs XL2596
- LM2596-ADJ calculator
- TI LM2596S-ADJ (TO-263)
- onsemi LM2596TADJG
- Buck converters
Sources (retrieved 2026-10-26)
- XLSEMI, XL2596 3A 150KHz 40V Buck DC to DC Converter, Rev 2.7: http://www.xlsemi.com/datasheet/XL2596-EN.pdf. Checked against a mirror copy of this PDF (sha256 f5506c70…114b); the official download did not complete on 26 Oct 2026, so we cannot prove it is the newest issue.
- 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 XLSEMI XL2596 Rev 2.7 (checked against a mirror copy), read on 26 Oct 2026. XLSEMI specifies limits at 25 °C only; worked numbers are our arithmetic. Verify against the current datasheet and test on your board.
Reviewed by: Jasper · Updated: 2026-10-26