# HSY8121BABC

**HXY MOSFET** · DC-DC Converters · SOT-23-6L

HSY8121BABC from HXY MOSFET, in a SOT-23-6L. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | BST | passive | Bootstrap pin; connect a 10nF capacitor from this pin to SW. |
| 2 | GND | power_in | Ground reference pin for the regulator. |
| 3 | FB | input | Feedback input; connect an external resistor divider from the output to this pin to set VOUT (VREF is 0.8V typical). |
| 4 | EN | input | Enable pin for the IC; drive high to enable the part and low to disable it, with an internal 1MΩ pull-down to GND. |
| 5 | VIN | power_in | Supply voltage input, specified 4.2V to 28V with a surge capability to 30V; bypass with a 4.7μF ceramic capacitor to GND. |
| 6 | SW | output | Inductor connection; connect the inductor between SW and the regulator output. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | HXY MOSFET |
| Package | SOT-23-6L |
| Category | Power Management ICs |
| Pins | 6 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Input Voltage Range |  | 4.2 |  | 28 | V |  | 3 |
| FB Voltage | VFB | 0.784 | 0.8 | 0.816 | V |  | 3 |
| Input UVLO Rising |  |  | 4.2 |  | V | Hysteresis=340mV | 3 |
| Input Supply Current |  |  | 750 |  | µA | Vin=12V, Iout=0 | 3 |
| Input Shutdown Current |  |  | 7 | 14 | µA |  | 3 |
| FB Input Current |  |  | 0 | 1 | µA |  | 3 |
| Switching Frequency |  |  | 1000 |  | kHz |  | 3 |
| Maximum Duty Cycle |  |  | 99 |  | % |  | 3 |
| Short Circuit Hiccup Time On Time |  |  | 2 |  | mS |  | 3 |
| Short Circuit Hiccup Time Off Time |  |  | 6 |  | mS |  | 3 |
| FB Hiccup Threshold |  |  | 0.2 |  | V |  | 3 |
| On Resistance (high side switch) |  |  | 160 |  | mΩ |  | 3 |
| On Resistance (low side switch) |  |  | 95 |  | mΩ |  | 3 |
| High Side Current Limit |  |  | 3.5 |  | A |  | 3 |
| SW Leakage Current |  |  | 20 |  | µA | IN=SW=12V | 3 |
| EN Rising Threshold |  |  | 1.5 |  | V |  | 3 |
| EN Falling Threshold |  |  | 1.3 |  | V |  | 3 |
| EN Input Current |  |  | 1 |  | uA | VEN=2V | 3 |
| Thermal Shutdown Rising |  |  | 150 |  | °C | Hysteresis =40°C | 3 |
| IN, SW, EN Voltage |  | -0.3 |  | 30 | V |  | 2 |
| BST Voltage |  | -0.3 |  |  | V | Printed as SW+6V (relative to SW) | 2 |
| FB Voltage |  | -0.3 |  | 6 | V |  | 2 |
| Operating Temperature Range |  | -40 |  | 85 | °C |  | 2 |
| Storage Temperature Range |  | -55 |  | 150 | °C |  | 2 |
| ESD HBM (Human Body Model) |  |  |  | 2 | KV |  | 2 |
| Thermal Resistance Junction-to-Case (SOT-23-6L) | JC |  | 90 |  | °C/W |  | 2 |

## CAD (KiCad official)

- Symbol: `HSY8121BABC`
- Footprint: `Package_TO_SOT_SMD:SOT-23-6`
- 3D model: SOT-23-6L (KiCad packages3D, STEP)
- 3D model files: `hsy8121babc-etched.step` / `hsy8121babc-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `hsy8121babc.step` / `hsy8121babc.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [HXY MOSFET datasheet](docs/hsy8121babc-datasheet.pdf) (8 pp, sha256 `f0739a7c4b602d31`, retrieved 2026-11-04, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-5-5` (text), consensus `claude-sonnet-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/hsy8121babc-datasheet.pdf)