# SI24R2E

**Nanjing Zhongke Microelectronics** · RF Chips · QFN-20-EP(4x4)

SI24R2E from Nanjing Zhongke Microelectronics, in a QFN-20-EP(4x4). 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 | CE | input | Chip Enable turns the chip on and must be kept clear of disassembly, as stated in the pin function table. |
| 2 | CSN | input | SPI Chip Select; every new SPI command must start with a high-to-low transition on this pin. |
| 3 | SCK | input | SPI Clock input, with a maximum SCK frequency of 10 MHz. |
| 4 | MOSI | input | SPI data input from the master, MOSI (Master Out Slave In). |
| 5 | MISO | output | SPI data output to the master; the first byte shifted out is always the STATUS register. |
| 6 | IRQ | output | Maskable interrupt output, active low. |
| 7 | VCC | power_in | Power supply, +1.9 to +3.6 V DC. |
| 8 | VSS | power_in | Ground, 0 V. |
| 9 | XO | output | Crystal oscillator output, for the 16 MHz crystal (±60 ppm). |
| 10 | XI | input | Crystal oscillator input, for the 16 MHz crystal (±60 ppm). |
| 11 | VDD_PA | power_out | 1.8 V supply output for the internal power amplifier. |
| 12 | RFP | passive | RF antenna port 1 (differential RF pair with RFN). |
| 13 | RFN | passive | RF antenna port 2 (differential RF pair with RFP). |
| 14 | VSS | power_in | Ground, 0 V. |
| 15 | VCC | power_in | Power supply, +1.9 to +3.6 V DC. |
| 16 | IREF | input | Reference current input for the internal bias. |
| 17 | VSS | power_in | Ground, 0 V. |
| 18 | VCC | power_in | Power supply, +1.9 to +3.6 V DC. |
| 19 | VDD_D | power_out | Positive digital supply output for decoupling purposes. |
| 20 | VSS | power_in | Ground, 0 V. |
| 21 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Nanjing Zhongke Microelectronics |
| Package | QFN-20-EP(4x4) |
| Category | Radio Frequency Chip/Antenna |
| Pins | 21 |

## 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 VDD | VDD | -0.3 |  | 3.6 | V |  | 23 |
| Input Voltage | VI | -0.3 |  | 5.25 | V |  | 23 |
| Power Dissipation |  |  |  | 100 | mW |  | 23 |
| Operation Temperature |  | -40 |  | 85 | ℃ |  | 23 |
| Storage Temperature |  | -40 |  | 125 | ℃ |  | 23 |
| Supply voltage | VDD | 1.9 |  | 3.6 | V |  | 23 |
| RF operation frequency | FOP | 2400 |  | 2525 | MHz |  | 24 |
| Frequency deviation 2Mbps | ΔFMOD(2Mbps) | -330 |  | 330 | KHz |  | 24 |
| Frequency deviation 1M/250Kbps | ΔFMOD(1M/250Kbps) | -175 |  | 175 | KHz |  | 24 |
| Data rate | RGFSK | 250 |  | 2000 | Kbps |  | 24 |
| RF Output Power | PRF | -30 |  | 7 | dBm |  | 24 |
| 1st Adjacent CH Power 2MHz | PRF1 |  |  | -20 | dBm | 1st Adjacent CH Power 2MHz | 25 |
| 2nd Adjacent CH Power 4MHz | PRF2 |  |  | -46 | dBm | 2nd Adjacent CH Power 4MHz | 25 |
| Crystal frequency tolerance | ΔF | -60 |  | 60 | ppm |  | 25 |
| Tdc Data to SCK Setup | Tdc | 2 |  |  | ns |  | 18 |
| SCK to Data Hold | Tdh | 2 |  |  | ns |  | 18 |
| CSN to Data Valid | Tcsd |  |  | 42 | ns |  | 18 |
| SCK to Data Valid | Tcd |  |  | 58 | ns |  | 18 |
| SCK Low Time | Tcl | 40 |  |  | ns |  | 18 |
| SCK High Time | Tch | 40 |  |  | ns |  | 18 |
| SCK Frequency | Fsck | 0 |  | 10 | MHz |  | 18 |
| SCK Rise and Fall | Tr,Tf |  |  | 100 | ns |  | 18 |
| CSN to SCK Setup | Tcc | 2 |  |  | ns |  | 18 |
| SCK to CSN Hold | Tcch | 2 |  |  | ns |  | 18 |
| CSN Inactive time | Tcwh | 50 |  |  | ns |  | 18 |
| CSN to Output High Z | Tcdz |  |  | 42 | ns |  | 18 |
| Supply current in Shutdown mode | ISHD |  | 0.7 |  | µA |  | 23 |
| Supply current in Sleep mode | Isleep |  | 0.7 |  | uA | RCOSC,Watchdog and ATR Timer are active | 23 |
| Supply current in Standby mode | ISTB |  | 15 |  | µA |  | 23 |
| Supply current in Idle-TX mode | IIDLE |  | 380 |  | µA |  | 23 |
| TX mode supply current @7 dBm output power | ITX@7dBm |  | 25 |  | mA | @7 dBm output power | 24 |
| TX mode supply current @4 dBm output power | ITX@4dBm |  | 17 |  | mA | @4 dBm output power | 24 |
| TX mode supply current @0 dBm output power | ITX@0dBm |  | 13.5 |  | mA | @0 dBm output power | 24 |
| TX mode supply current @-6 dBm output power | ITX@-6dBm |  | 10 |  | mA | @-6 dBm output power | 24 |
| TX mode supply current @-12 dBm output power | ITX@-12dBm |  | 8.5 |  | mA | @-12 dBm output power | 24 |
| RF channel space | FCH |  | 1 |  | MHz | 2MHz at least when 2Mpbs | 24 |
| Modulation Bandwidth 2Mbps | PBW@2Mbps |  | 2.1 |  | MHz |  | 24 |
| Modulation Bandwidth 1Mbps | PBW@1Mbps |  | 1.1 |  | MHz |  | 24 |
| Modulation Bandwidth 250Kbps | PBW@250Kbps |  | 0.9 |  | MHz |  | 24 |
| Crystal frequency | FXO |  | 16 |  | MHz |  | 25 |
| Equivalent Series Resistance | ESR |  | 100 |  | Ω |  | 25 |

## CAD (KiCad official)

- Symbol: `SI24R2E`
- Footprint: `Package_DFN_QFN:QFN-20-1EP_4x4mm_P0.5mm_EP2.5x2.5mm`
- 3D model: QFN-20-EP(4x4) (KiCad packages3D, STEP)
- 3D model files: `si24r2e-etched.step` / `si24r2e-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `si24r2e.step` / `si24r2e.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Nanjing Zhongke Microelectronics datasheet](docs/si24r2e-datasheet.pdf) (37 pp, sha256 `15175c73931821a7`, retrieved 2026-10-27, 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/si24r2e-datasheet.pdf)