# CSM9241

**Nanjing Zhongke Microelectronics** · Receivers & Transceivers · SO-8

CSM9241 from Nanjing Zhongke Microelectronics, in a SO-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 | VDD | power_in | Logic power supply, +4.5V to +5.5V DC. |
| 2 | TX | input | Transmit input with internal pull-up to VDD; low level below 1.5V, high level above 3.5V. |
| 3 | CS | input | Active-low chip select input with internal pull-up to VDD; low enables transmit mode, high selects receive mode and resets a fault. |
| 4 | FAULT | output | Active-low fault detection output asserted on over temperature or short circuit to VBAT, with output low voltage max 0.4V at 1mA. |
| 5 | GND | power_in | Ground (0V). |
| 6 | K | bidirectional | Transmit/receive K bus line, operating range 6V to 36V, compared internally to VBAT/2 for receive. |
| 7 | VBAT | power_in | Battery power supply, +6V to +36V DC. |
| 8 | RX | output | Receiver output with internal pull-up to VDD, low when K is below VBAT/2 and high when above, driving CMOS or 1 LSTTL load. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Nanjing Zhongke Microelectronics |
| Package | SO-8 |
| Category | Logic ICs |
| 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 |
|---|---|---|---|---|---|---|---|
| Voltage on VBAT | VBAT | -24 |  | 45 | V | Referenced to ground | 7 |
| Voltage on K | K | -16 |  |  | V | Referenced to ground; max printed as VBAT + 1 | 7 |
| Voltage difference V(VBAT, K) | V(VBAT,K) |  |  | 55 | V |  | 7 |
| Voltage on VDD | VDD |  |  | 7 | V |  | 7 |
| Current on any pin (except VBAT, K) |  |  |  | 10 | mA | Voltage range -0.3 to (VDD + 0.3) V or 10 mA | 7 |
| Operating Temperature | TA | -40 |  | 125 | °C |  | 7 |
| Junction and Storage Temperature |  | -55 |  | 150 | °C |  | 7 |
| Thermal Impedance |  |  | 125 |  | °C/W |  | 7 |
| Operating range VDD | VDD | 4.5 |  | 5.5 | V |  | 7 |
| Operating range VBAT | VBAT | 6 |  | 36 | V |  | 7 |
| Operating range K | K | 6 |  | 36 | V |  | 7 |
| CS, TX Input Low Voltage | VILT |  |  | 1.5 | V | Full | 8 |
| CS, TX Input High Voltage | VIHT | 3.5 |  |  | V | Full | 8 |
| CS, TX Input Pull-up Resistance | RTX | 10 | 20 | 40 | kΩ | VDD = 5.5 V, or CS=1.5V, 3.5 V; Full | 8 |
| K Output Low Voltage | VOLK |  |  | 0.2 | V | RL = 510Ω ± 5 %, VBAT = 6 to 18V; Full (printed 0.2VBAT) | 8 |
| K Output Low Voltage | VOLK |  |  | 1.2 | V | RL = 510Ω ± 5 %, VBAT = 4.5V; Full | 8 |
| K Output High Voltage | VOHK | 0.95 |  |  | V | RL = 510Ω ± 5 %, VBAT = 6 to 18V; Full (printed 0.95VBAT) | 8 |
| K Rise Time | tr |  |  | 9 | μs | See Test Circuit; Full | 8 |
| K Fall Time | tf |  |  | 1 | μs | See Test Circuit; Full | 8 |
| K Output Sink Resistance | Rsi |  |  | 110 | Ω | CS = 0 V, TX = 0 V; Full | 8 |
| K Input Low Voltage | VILK |  |  | 0.35 | V | Full (printed 0.35VBAT) | 8 |
| K Input High Voltage | VIHK | 0.65 |  |  | V | Full (printed 0.65VBAT) | 8 |
| K Input Currents | IIHK |  | 3 | 20 | μA | CS=High, VIHK = VBAT; Full | 8 |
| RX Output Low Voltage | VOLR |  |  | 0.4 | V | VILK=0.35VBAT, IOLR = 1 mA; Full | 8 |
| RX Pull-up Resistance | RRX | 5 |  | 20 | kΩ | Full | 8 |
| RX Turn On Delay | td(on) | 1 |  | 10 | μs | RL = 510Ω ± 5 %, VBAT = 6 to 18 V, CL = 10 nF; Full | 8 |
| RX Turn Off Delay | td(off) | 6 |  | 10 | μs | RL = 510Ω ± 5 %, VBAT = 6 to 18 V, CL = 10 nF; Full | 9 |
| Bat Supply Current On | IBAT(on) |  | 0.06 | 3 | mA | CS = TX = 0 V, VBAT≦16 V; Full | 9 |
| Bat Supply Current Off | IBAT(off) |  | 60 | 220 | μA | CS=High, VBAT ≦12 V, TX = High; Full | 9 |
| Bat Supply Current Standby | IBAT(SB) |  | 1 | 10 | μA | VDD ≦0.5 V, VBAT ≦12 V; Full (typ printed <1) | 9 |
| Logic Supply Current On | IDD(on) |  | 0.9 | 2.3 | mA | VDD≦5.5 V, TX = 0 V; Full | 9 |
| Logic Supply Current Off | IDD(off) |  | 2.5 | 10 | μA | CS=High, VBAT ≦ 12V, TX = High; Full | 9 |
| Fault Output Low Voltage | VOLF |  |  | 0.4 | V | CS = TX = 0, K = VBAT, IOLF = 1 mA; Full | 9 |
| Over Temperature Shutdown | TSHUT | 160 |  | 180 | °C | Temperature Rising | 9 |
| TX Input Capacitance | CINT |  |  | 10 | pF | Full | 8 |
| K Output Capacitance | CO |  |  | 20 | pF | Full | 8 |
| Temperature Shutdown Hysteresis | THYST |  | 30 |  | °C |  | 9 |
| Transmission Frequency | fK-RXK | 50 |  | 200 | kHz | 6 V < VBAT < 16 V, RK = 510 Ω, CK ≦1.3 nF; Full | 9 |

## CAD (KiCad official)

- Symbol: `CSM9241`
- Footprint: `Package_SO:SOIC-8_3.9x4.9mm_P1.27mm`
- 3D model: SO-8 (KiCad packages3D, STEP)
- 3D model files: `csm9241-etched.step` / `csm9241-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `csm9241.step` / `csm9241.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Nanjing Zhongke Microelectronics datasheet](docs/csm9241-datasheet.pdf) (15 pp, sha256 `7ba3c2e260ec7b98`, retrieved 2026-10-31, tier: lcsc)
- **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/csm9241-datasheet.pdf)