From 83ca5bb3c03d0bd159ca1235dca974eda1ecd04a Mon Sep 17 00:00:00 2001
From: Joel Rubio <283646368+joel777rubio-web@users.noreply.github.com>
Date: Tue, 12 May 2026 11:04:06 +0200
Subject: [PATCH] Add UTDFN-4-EP footprint

---
 src/fn/index.ts     |  1 +
 src/fn/utdfn.ts     | 62 +++++++++++++++++++++++++++++++++++++++++++++
 src/footprinter.ts  |  7 +++++
 tests/utdfn.test.ts | 17 +++++++++++++
 4 files changed, 87 insertions(+)
 create mode 100644 src/fn/utdfn.ts
 create mode 100644 tests/utdfn.test.ts

diff --git a/src/fn/index.ts b/src/fn/index.ts
index 94c0370e..ddc2e7cb 100644
--- a/src/fn/index.ts
+++ b/src/fn/index.ts
@@ -67,6 +67,7 @@ export { sod323w } from "./sod323w"
 export { sod323fl } from "./sod323fl"
 export { son } from "./son"
 export { vson } from "./vson"
+export { utdfn } from "./utdfn"
 export { solderjumper } from "./solderjumper"
 export { sot457 } from "./sot457"
 export { sot963 } from "./sot963"
diff --git a/src/fn/utdfn.ts b/src/fn/utdfn.ts
new file mode 100644
index 00000000..dc25daa8
--- /dev/null
+++ b/src/fn/utdfn.ts
@@ -0,0 +1,62 @@
+import type { AnyCircuitElement, PcbCourtyardRect } from "circuit-json"
+import { length, distance } from "circuit-json"
+import { rectpad } from "../helpers/rectpad"
+import { z } from "zod"
+import { base_def } from "../helpers/zod/base_def"
+import { dim2d } from "src/helpers/zod/dim-2d"
+import { type SilkscreenRef, silkscreenRef } from "src/helpers/silkscreenRef"
+
+export const utdfn_def = base_def.extend({
+  fn: z.string(),
+  num_pins: z.number().default(4),
+  p: distance.default("0.35mm"),
+  w: length.default("0.65mm"),
+  grid: dim2d.default("1x1mm"),
+  pinw: length.default("0.2mm"),
+  pinh: length.default("0.35mm"),
+  ep: dim2d.default("0.35x0.35mm"),
+})
+
+export const utdfn = (
+  raw_params: z.input<typeof utdfn_def>,
+): { circuitJson: AnyCircuitElement[]; parameters: any } => {
+  const parameters = utdfn_def.parse(raw_params)
+  const pads: AnyCircuitElement[] = []
+
+  if (parameters.num_pins !== 4) {
+    throw new Error("UTDFN currently supports 4 pins")
+  }
+
+  for (let i = 0; i < parameters.num_pins; i++) {
+    const leftSide = i < 2
+    const pinIndexOnSide = i % 2
+    const y = (pinIndexOnSide === 0 ? 1 : -1) * (parameters.p / 2)
+    const x = (leftSide ? -1 : 1) * (parameters.w / 2)
+    pads.push(rectpad(i + 1, x, y, parameters.pinw, parameters.pinh))
+  }
+
+  if (parameters.ep.x > 0 && parameters.ep.y > 0) {
+    pads.push(rectpad(parameters.num_pins + 1, 0, 0, parameters.ep.x, parameters.ep.y))
+  }
+
+  const courtyard: PcbCourtyardRect = {
+    type: "pcb_courtyard_rect",
+    pcb_courtyard_rect_id: "",
+    pcb_component_id: "",
+    center: { x: 0, y: 0 },
+    width: parameters.grid.x + 0.5,
+    height: parameters.grid.y + 0.5,
+    layer: "top",
+  }
+
+  const silkscreenRefText: SilkscreenRef = silkscreenRef(
+    0,
+    parameters.grid.y / 2 + 0.25,
+    0.15,
+  )
+
+  return {
+    circuitJson: [...pads, silkscreenRefText, courtyard],
+    parameters,
+  }
+}
diff --git a/src/footprinter.ts b/src/footprinter.ts
index fa51a3b4..f792d036 100644
--- a/src/footprinter.ts
+++ b/src/footprinter.ts
@@ -182,6 +182,9 @@ export type Footprinter = {
   ) => FootprinterParamsBuilder<
     "p" | "w" | "grid" | "ep" | "epx" | "pinw" | "pinh"
   >
+  utdfn: (
+    num_pins?: number,
+  ) => FootprinterParamsBuilder<"p" | "w" | "grid" | "ep" | "pinw" | "pinh">
   vssop: (
     num_pins?: number,
   ) => FootprinterParamsBuilder<"w" | "h" | "p" | "pl" | "pw">
@@ -271,6 +274,10 @@ const normalizeDefinition = (def: string): string => {
   return def
     .trim()
     .replace(/^pinheader(?=[\d_]|$)/i, "pinrow")
+    .replace(
+      /^utdfn-?4-?ep\(?1x1\)?(?=_|$)/i,
+      "utdfn_4_p0.35_w0.65_grid1x1mm_pinw0.2_pinh0.35_ep0.35x0.35mm",
+    )
     .replace(/^sot23-(\d+)(?=_|$)/i, "sot23_$1")
     .replace(/^sot-223-(\d+)(?=_|$)/i, "sot223_$1")
     .replace(/^to-220f-(\d+)(?=_|$)/i, "to220f_$1")
diff --git a/tests/utdfn.test.ts b/tests/utdfn.test.ts
new file mode 100644
index 00000000..75f0e78d
--- /dev/null
+++ b/tests/utdfn.test.ts
@@ -0,0 +1,17 @@
+import { test, expect } from "bun:test"
+import { convertCircuitJsonToPcbSvg } from "circuit-to-svg"
+import { fp } from "../src/footprinter"
+
+test("UTDFN-4-EP(1x1) aliases to configured VSON footprint", () => {
+  const utdfnCircuitJson = fp.string("UTDFN-4-EP(1x1)").circuitJson()
+  const canonicalCircuitJson = fp
+    .string("utdfn_4_p0.35_w0.65_grid1x1mm_pinw0.2_pinh0.35_ep0.35x0.35mm")
+    .circuitJson()
+
+  expect(convertCircuitJsonToPcbSvg(utdfnCircuitJson)).toEqual(
+    convertCircuitJsonToPcbSvg(canonicalCircuitJson),
+  )
+  expect(
+    utdfnCircuitJson.filter((elm) => elm.type === "pcb_smtpad"),
+  ).toHaveLength(5)
+})