# MD8942

**Shanghai Mingda Microelectronics** · DC-DC Converters · SOT-23-6L

MD8942 from Shanghai Mingda Microelectronics, in a SOT-23-6L. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | BST | passive | Bootstrap pin providing gate-drive bias for the internal high-side switch FET. Connect a bootstrap capacitor (Cboot) between BST and SW. Absolute max BST-to-SW voltage is 6V; internally charged to ~5V from VCB through a diode. |
| 2 | GND | power_in | Device ground connection. Should be connected as close as possible to the output capacitor to avoid high current switching paths and to serve as the reference for feedback and enable. |
| 3 | FB | input | Feedback input to the internal error amplifier. Set the output voltage via a resistor divider from VOUT to FB using VOUT = VFB × (1 + R2/R1), where VFB is typically 0.794V. Absolute max -0.3V to 6V. |
| 4 | EN | input | Enable input, active-high logic. Pulling EN above the ~1V rising threshold enables the chip; pulling below the falling threshold (~0.84V, 160mV hysteresis) shuts it down. Floating EN disables the chip (internal 430kΩ pull-down to GND). Internal zener clamps EN to ~5V, absolute max 6V, sink current limit 100µA. |
| 5 | VIN | power_in | Input supply pin. Operating range 4V to 36V, standoff input voltage 42V. Bypass with a low-ESR ceramic input capacitor (typ. 10µF) placed as close as possible to VIN and GND. |
| 6 | SW | output | Switch node - the output of the internal high-side and low-side power MOSFETs. Connect to the external inductor and to the bootstrap capacitor's low side. Absolute max -0.3V to VIN(MAX)+0.3V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Shanghai Mingda Microelectronics |
| Package | SOT-23-6L |
| Category | PMIC |
| 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 |
|---|---|---|---|---|---|---|---|
| Supply Voltage (VIN) | VIN | -0.3 |  | 42 | V |  | 2 |
| Switch Voltage (VSW), max printed as VIN(MAX)+0.3V | VSW | -0.3 |  |  | V |  | 2 |
| BST to SW |  | -0.3 |  | 6 | V |  | 2 |
| Enable (VEN) | VEN |  |  | 6 | V |  | 2 |
| Enable Sink Current (VEN) |  |  |  | 100 | μA |  | 2 |
| All Other Pins |  | -0.3 |  | 6 | V |  | 2 |
| Storage Temperature Range |  | -65 |  | 150 | ℃ |  | 2 |
| Junction Temperature |  |  |  | 150 | ℃ |  | 2 |
| Operating Temperature Range |  | -40 |  | 85 | ℃ |  | 2 |
| ESD Human Body Model (HBM) |  | 2 |  |  | kV | HBM, minimum level | 2 |
| Input Voltage Range | VIN_R | 4 |  | 36 | V |  | 3 |
| VIN UVLO Up Threshold | VUVLO_U | 3.2 | 3.6 | 3.9 | V |  | 3 |
| Feedback Voltage | VFB | 0.778 | 0.794 | 0.81 | V | 4.8V < VIN < 36V, Iout=10mA | 3 |
| Oscillator Frequency | fSW | 880 | 1100 | 1320 | kHz |  | 3 |
| Input Standoff Voltage | VIN_S |  | 42 |  | V | VEN = 0V | 3 |
| VIN UVLO Hysteresis | VUVLO_HYS |  | 0.3 |  | V |  | 3 |
| High-Side Switch on Resistance | RON_HS |  | 650 |  | mOhms | VBST-VSW=5V | 3 |
| Low-Side Switch on Resistance | RON_LS |  | 650 |  | mOhms |  | 3 |
| High-Side Switch Leakage | ISW_HS_LKG |  | 0.1 |  | μA | VEN = 0V, VSW = 0V | 3 |
| Low-Side Switch Leakage | ISW_LS_LKG |  | 0.2 |  | μA | VEN = 0V, VSW = VIN | 3 |
| Peak Inductor Current Limit | IHS_Limit |  | 1.2 |  | A |  | 3 |
| COMP to Current Sense Transconductance | GCS |  | 2.7 |  | A/V |  | 3 |
| Soft-start time | TSS |  | 0.5 |  | msec | VFB from 0 to 0.8V | 3 |
| Foldback Frequency | fSW_F |  | 80 |  | kHz |  | 3 |
| Minimum Switch on Time | τON |  | 100 |  | ns |  | 3 |
| Shutdown Supply Current | ISHDN |  | 3 |  | μA | VEN = 0V | 3 |
| Average Quiescent Supply Current | IQ |  | 130 |  | μA | No load, VFB = 0.9V | 3 |
| Thermal Shutdown | TSD |  | 155 |  | ℃ |  | 3 |
| Thermal Shutdown Hysteresis | TSD_HYS |  | 20 |  | ℃ |  | 3 |
| Enable up Threshold | VEN_U |  | 1 |  | V |  | 3 |
| Enable Threshold Hysteresis | VEN_HYS |  | 0.16 |  | V |  | 3 |
| Enable Clamping Voltage |  |  | 5 |  | V |  | 3 |
| Enable Pull-Down Resistance |  |  | 430 |  | kOhms |  | 3 |

## CAD (KiCad official)

- Symbol: `MD8942`
- Footprint: `Package_TO_SOT_SMD:SOT-23-6`
- 3D model: SOT-23-6L (KiCad packages3D, STEP)
- 3D model files: `md8942-etched.step` / `md8942-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `md8942.step` / `md8942.glb` are the bare package body.

## 3D model downloads

Two STEP files. Same geometry, different body top:

| File | Size | Use it when |
|---|---|---|
| [`md8942.step`](md8942.step) | 97 KB | You want the bare part, or you mark your own boards. |
| [`md8942-etched.step`](md8942-etched.step) | 1.5 MB | You want the part with `MD8942` already on it. |

The marking in the etched file is real recessed geometry cut into the solid, not a
texture or a decal: 360 faces against 117 in the bare model. It
survives export, section views, and rendering in any CAD tool, and it drops straight
into KiCad or Fusion with no extra setup.

## Provenance

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

- **Datasheet:** [Shanghai Mingda Microelectronics datasheet](docs/md8942-datasheet.pdf) (13 pp, sha256 `758503482648cacf`, retrieved 2026-08-17, tier: lcsc)
- **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/md8942-datasheet.pdf)