SN74HC237

@@ -0,0 +1,60 @@+# SN74HC237++**Texas Instruments** · 3-to-8 decoder with address latch · SOIC-16++A 3-to-8 line decoder/demultiplexer with a built-in address latch, in high-speed CMOS, SOIC-16. Like the 74HC138 it drives one of eight outputs from a 3-bit address, but here the outputs are active-high and a latch-enable pin can freeze the address so the selected output stays put after the address bus moves on. That suits multiplexed-bus systems where the address appears only briefly. Two output-enable inputs gate the whole device and allow cascading. Runs 2-6 V.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | A0 | input | Address select input bit 0 (LSB). Combined with A1 and A2 selects which of eight Y outputs is driven high. Latched by LE; transparent when LE is low, held on the LE low-to-high transition. |+| 2 | A1 | input | Address select input bit 1. Combined with A0 and A2 selects which of eight Y outputs is driven high. Latched by LE. |+| 3 | A2 | input | Address select input bit 2 (MSB). Combined with A0 and A1 selects which of eight Y outputs is driven high. Latched by LE. |+| 4 | LE | input | Latch Enable, active low. When LE is low the address inputs A0-A2 pass transparently to the decoder; on the low-to-high transition of LE the current address is latched and further changes on A0-A2 are ignored. |+| 5 | ~{OE1} | input | Output Enable 1, active low. Must be low together with OE0 high to enable the selected Y output. When high, all outputs are forced to their inactive state (LOW for 'HC237/'HCT237). |+| 6 | OE0 | input | Output Enable 0, active high. Must be high together with /OE1 low to enable the selected Y output. When low, all outputs are forced to their inactive state (LOW for 'HC237/'HCT237). |+| 7 | Y7 | output | Decoded output 7 (address 111). Driven HIGH when selected and both enables active; otherwise LOW. Fanout 10 LSTTL loads (standard) / 15 LSTTL loads (bus driver). |+| 8 | GND | power_in | Ground reference (0 V) for logic and outputs. |+| 9 | Y6 | output | Decoded output 6 (address 110). Driven HIGH when selected and both enables active; otherwise LOW. |+| 10 | Y5 | output | Decoded output 5 (address 101). Driven HIGH when selected and both enables active; otherwise LOW. |+| 11 | Y4 | output | Decoded output 4 (address 100). Driven HIGH when selected and both enables active; otherwise LOW. |+| 12 | Y3 | output | Decoded output 3 (address 011). Driven HIGH when selected and both enables active; otherwise LOW. |+| 13 | Y2 | output | Decoded output 2 (address 010). Driven HIGH when selected and both enables active; otherwise LOW. |+| 14 | Y1 | output | Decoded output 1 (address 001). Driven HIGH when selected and both enables active; otherwise LOW. |+| 15 | Y0 | output | Decoded output 0 (address 000). Driven HIGH when selected and both enables active; otherwise LOW. |+| 16 | VCC | power_in | Positive supply. HC variant: 2 V to 6 V. HCT variant: 4.5 V to 5.5 V. Decouple with a local 0.1 uF ceramic to GND close to the pin. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | 3-to-8 decoder/demux, latched |+| Address | 3-bit (A0-A2), latchable |+| Outputs | 8 active-high (Y0-Y7) |+| Latch | LE holds the address |+| Enables | OE0 + /OE1 |+| Logic family | HC (high-speed CMOS) |+| Supply voltage | 2-6 V |+| Package | SOIC-16 |++## Ordering variants++- `CD74HC237M (SOIC-16, tube)`+- `CD74HC237M96 (SOIC-16, tape & reel)`++## CAD (KiCad official)++- Symbol: `74xx:74HC237`+- Footprint: `Package_SO:SOIC-16_3.9x9.9mm_P1.27mm`+- 3D model: SOIC-16 (KiCad packages3D)++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/cd74hc237.pdf) (27 pp, sha256 `564c040df4c1b784`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/sn74hc237-datasheet.pdf)

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