LM2596 (adjustable buck)

@@ -0,0 +1,50 @@+# LM2596S-ADJ++**Texas Instruments** · Buck switching regulator · TO-263-5 (D2PAK)++150 kHz fixed-frequency, 3 A step-down (buck) switching regulator with an integrated high-side switch, in a TO-263-5 (D2PAK) package. The output is adjustable from 1.2 V to 37 V via a divider on the FB pin (VREF = 1.23 V). It has internal loop compensation, a TTL-compatible ON/OFF pin, thermal shutdown, and cycle-by-cycle current limit, and needs only an inductor, catch diode, and input/output capacitors. The workhorse behind countless cheap buck modules.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | VIN | power_in | Positive input supply for the switching regulator, 4.5 V to 40 V operating (45 V absolute max). A low-ESR bypass capacitor must be placed directly at this pin to supply the switch currents and minimize input transients. |+| 2 | Output | output | Internal high-side switch node (SW). Swings between approximately (VIN - VSAT) and about -0.5 V (catch-diode drop) with duty cycle VOUT/VIN; connect to the external inductor and Schottky catch diode. PCB copper area on this node must be minimized to reduce EMI coupling. |+| 3 | GND | power_in | Circuit ground and power return for the regulator. On the TO-263 (KTT) package the metal tab is also GND. |+| 4 | FB | input | Feedback input to the error amplifier, regulated to VREF = 1.23 V (typ) on the -ADJ version. Connect to the R1/R2 external divider from VOUT: VOUT = 1.23 V x (1 + R2/R1). Feedback bias current is typically 10 nA (50 nA max at 25 degC). Absolute-max range -0.3 V to 25 V. |+| 5 | ON/OFF | input | TTL-compatible active-low shutdown input. Pulling below ~1.3 V (or tying to GND / leaving open) enables the regulator; driving above ~1.3 V (up to 25 V max) shuts it down and drops total supply current to ~80 uA typ. Internally clamped; input current 5 uA typ at VLOGIC = 2.5 V. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | Buck (step-down) switching regulator |+| Switching frequency | 150 kHz (fixed) |+| Output current | 3 A |+| Output voltage | 1.2-37 V adjustable (VREF 1.23 V) |+| Input voltage | up to 40 V |+| Control | TTL-compatible ON/OFF |+| Protection | Thermal shutdown + cycle-by-cycle current limit |+| Package | TO-263-5 (D2PAK) |+| Body (L×W×H) | 10.2 × 8.4 × 4.6 mm |++## Ordering variants++- `LM2596S-ADJ (TO-263, tape & reel)`+- `LM2596T-ADJ (TO-220-5)`++## CAD (KiCad official)++- Symbol: `Regulator_Switching:LM2596S-ADJ`+- Footprint: `Package_TO_SOT_SMD:TO-263-5_TabPin3`+- 3D model: TO-263-5 (KiCad packages3D)++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/lm2596.pdf) (47 pp, sha256 `fbd0a8af4dcd4c37`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude) — every pin and dimension is cited to a datasheet page; refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/lm2596-adj-datasheet.pdf)

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