# LM331P

**Sungine** · V/F And F/V Converters · SOP-8

LM331P from Sungine, in a SOP-8. 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 | CURO | output | Current output (switched current source output, flows to pin 1 or GND depending on RS flip-flop state; current range 10 to 500 µA). |
| 2 | REFCUR | output | Reference current pin held at 1.9V (1.70 to 2.08V) by the charge pump, setting i = 1.9V/Rs (135 µA at Rs = 14k); do not draw current from it. |
| 3 | FOUT | output | Frequency output driver transistor with about 50 ohm saturation resistance, output current limited below 50 mA and tolerates up to 40V. |
| 4 | GND | power_in | Ground. |
| 5 | R/C | input | Timing comparator input for external Rt/Ct, threshold 2/3 of VS (0.667 typ) that resets the RS flip-flop. |
| 6 | THD | input | Input comparator inverting input; comparator triggers timer when pin 7 voltage is higher than pin 6. |
| 7 | COM I | input | Input comparator non-inverting input with bias current of -80 nA typ, common-mode range -0.2V to VCC-2.0V. |
| 8 | VS | power_in | Power supply, 4.0V to 40V operating (absolute maximum 40V). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Sungine |
| Package | SOP-8 |
| Category | Data Acquisition |
| Pins | 8 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| VFC nonlinearity |  | -0.01 | 0.003 | 0.01 | % full scale | 4.5V≤VS≤20V | 4 |
| VFC nonlinearity over temperature |  | -0.02 | 0.006 | 0.02 | % full scale | TMIN≤TA≤TMAX | 4 |
| VFC nonlinearity (Fig 3) |  | -0.14 | 0.024 | 0.14 | % full scale | VS=15V, f=10~11kHz | 4 |
| Conversion accuracy scale factor |  | 0.9 | 1 | 1.1 | kHz/V | VIN=-10V, RS=14kΩ | 4 |
| Gain temperature stability LM331 |  | -150 | 30 | 150 | ppm/℃ | TMIN≤TA≤TMAX, 4.5V≤VS≤20V | 4 |
| Gain change with VS (4.5V-10V) |  |  | 0.01 | 0.1 | %/V | 4.5V≤VS≤10V | 4 |
| Gain change with VS (10V-40V) |  |  | 0.006 | 0.06 | %/V | 10V≤VS≤40V | 4 |
| Rated full-scale frequency |  |  | 10 |  | kHz | VIN=-10V | 4 |
| Long-term gain stability (1000 h) |  |  | 0.02 |  | % full scale | TMIN≤TA≤TMAX | 4 |
| Overrange frequency |  |  | 10 |  | % | VIN=-11V | 4 |
| Input comparator offset voltage LM331 |  | -14 | 4 | 14 | mV | TMIN≤TA≤TMAX | 4 |
| Input comparator bias current |  |  | -80 | -300 | nA |  | 4 |
| Input comparator offset current |  | -100 | 8 | 100 | nA |  | 4 |
| Input comparator common-mode range |  | -0.2 |  |  | V | TMIN≤TA≤TMAX; max VCC-2.0 | 4 |
| Timer threshold voltage (pin 5) |  | 0.63 | 0.667 | 0.7 | *VS |  | 4 |
| Timer input bias current (pin 5), all drive |  | -100 | 10 | 100 | nA | VS=15V, 0V≤Vpin5≤9.9V, all drive | 4 |
| Timer input bias current (pin 5) LM1/2/331 |  |  | 200 | 1000 | nA | Vpin5=10V, LM1/2/331 | 4 |
| VSAT (pin 5 reset) | VSAT |  | 0.22 | 0.5 | V | I=5mA | 4 |
| Current source output current (pin 1) |  | 116 | 136 | 156 | µA | RS=14kΩ, VPIN1=0 | 5 |
| Change in output current with voltage |  |  | 0.2 | 1 | µA | 0V≤VPIN1≤10V | 5 |
| Current source off leakage |  |  | 0.02 | 10 | nA |  | 5 |
| Current source off leakage at TMAX |  |  | 2 | 50 | nA | TA=TMAX, all drive | 5 |
| Operating current range |  | 10 |  | 500 | µA |  | 5 |
| Reference voltage (pin 2) |  | 1.7 | 1.89 | 2.08 | VDC |  | 5 |
| Reference voltage temperature stability |  |  | 60 |  | ppm/℃ |  | 5 |
| Reference voltage time stability (1000 h) |  |  | 0.1 |  | % | 1000 hours | 5 |
| Logic output VSAT (pin 3) | VSAT |  | 0.15 | 0.5 | V | I=5mA | 5 |
| Logic output VSAT, 2 TTL loads | VSAT |  | 0.1 | 0.4 | V | I=3.2mA (2 TTL loads), TMIN≤TA≤TMAX | 5 |
| Logic output off leakage |  | -1 | 0.05 | 1 | µA |  | 5 |
| Supply current |  | 1.5 | 3 | 6 | mA | VS=5V | 5 |
| Supply current |  | 2 | 4 | 8 | mA | VS=40V | 5 |
| Supply voltage | VS |  |  | 40 | V |  | 3 |
| Input voltage |  | -0.2 |  |  | V | max Vs | 3 |
| Operating temperature range LM331 |  | 0 |  | 70 | ℃ | LM331 | 3 |
| Power dissipation |  |  |  | 1.25 | W | 25℃ | 3 |
| Soldering temperature |  |  |  | 260 | ℃ | spot soldering, 10 seconds | 3 |
| Operating supply voltage | VS | 4 |  | 40 | V | conditions for tables 1 and 2 | 5 |

## CAD (KiCad official)

- Symbol: `LM331P`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SOP-8 (KiCad packages3D, STEP)
- 3D model files: `lm331p-etched.step` / `lm331p-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lm331p.step` / `lm331p.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Sungine datasheet](docs/lm331p-datasheet.pdf) (12 pp, sha256 `20bc1d95008650ea`, retrieved 2026-10-23, tier: lcsc)
- **Datasheet language:** Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-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/lm331p-datasheet.pdf)