# AT9880B

**ZHONGKEWEI** · GNSS Modules · QFN-40L-EP(5x5)

AT9880B from ZHONGKEWEI, in a QFN-40L-EP(5x5). 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 | RF1 | input | L1 band RF signal input; DC voltage on this pin must not exceed 0.8V, so a DC-blocking capacitor is needed if the external LNA output carries DC. |
| 2 | GND | power_in | Ground; connect to GND and use as part of the RF input isolation ground next to RF1. |
| 3 | VDD_ANA | power_out | Analog LDO output; connect a 1uF decoupling capacitor. |
| 4 | VX_OUT | power_out | Supply output for the external TCXO, typically 1.8V; connect a 1uF decoupling capacitor. |
| 5 | XREF | input | Reference clock input for an external TCXO (26 MHz, clipped sine, 0.5-1.5 Vpp). |
| 6 | TST_RF | passive | RF test port; leave unconnected when not used. |
| 7 | VDD_BK | power_out | Backup LDO output; a decoupling capacitor must be connected to this pin whether or not a backup supply is fitted. |
| 8 | VBAT | power_in | Backup power input for RTC and backup RAM, operating range 1.4-3.6V; may be left floating if no hot-start backup is needed. |
| 9 | VDD_IO | power_in | Digital I/O supply input, 2.7-3.6V (3.3V typical), also powering the power-on reset and antenna detect circuits. |
| 10 | ANT_BIAS | bidirectional | Active antenna bias output and detection; detection supply is VDD_IO up to 3.6V, with short-circuit protection limiting current to about 45-65 mA. |
| 11 | RTC_O | passive | RTC 32.768 kHz oscillator output for a passive crystal connected between RTC_I and RTC_O. |
| 12 | RTC_I | passive | RTC 32.768 kHz oscillator input for a passive crystal connected between RTC_I and RTC_O. |
| 13 | GPIO2/TXD1 | bidirectional | General-purpose I/O multiplexed as UART1 transmit (TXD1). |
| 14 | GPIO3/RXD1 | bidirectional | General-purpose I/O multiplexed as UART1 receive (RXD1). |
| 15 | Reserved | bidirectional | Reserved digital pin; leave unconnected when not used. |
| 16 | Reserved | bidirectional | Reserved digital pin; leave unconnected when not used. |
| 17 | nRST | input | External active reset input with internal pull-up; leave unconnected when not used. |
| 18 | GPIO1/RXD0 | bidirectional | General-purpose I/O multiplexed as UART0 receive (RXD0), the default navigation data interface. |
| 19 | GPIO0/TXD0 | bidirectional | General-purpose I/O multiplexed as UART0 transmit (TXD0), the default navigation data output. |
| 20 | GPIO27 | bidirectional | General-purpose I/O. |
| 21 | DX_IN | power_in | Internal DCDC input, 2.7-3.6V; place at least 2.2uF filter capacitance close to this pin. |
| 22 | DX_OUT | passive | Internal DCDC output; requires a 4.7uH inductor and at least 10uF output capacitor (recommended 4.7uH + 10uF), or left floating when an external core supply is used. |
| 23 | VCORE | power_in | Core LDO input, 1.2-3.6V; can be powered directly by an external supply. |
| 24 | VDD_BB | power_out | Digital core LDO output; connect a 2.2uF decoupling capacitor. |
| 25 | GPIO22 | bidirectional | General-purpose I/O, default function is 1PPS output. |
| 26 | Reserved | bidirectional | Reserved digital pin; leave unconnected when not used. |
| 27 | Reserved | bidirectional | Reserved digital pin; leave unconnected when not used. |
| 28 | Reserved | bidirectional | Test port; leave unconnected when not used. |
| 29 | ON_OFF | input | Shutdown control with internal pull-up; driving low puts the chip into sleep mode and high resumes full operation; leave unconnected when not used. |
| 30 | GPIO4 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 31 | GPIO5 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 32 | GPIO8 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 33 | GPIO7 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 34 | GPIO6 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 35 | GPIO10 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 36 | GPIO9 | bidirectional | General-purpose I/O; leave unconnected when not used. |
| 37 | DVDD | passive | PLL LDO output; connect a 1uF decoupling capacitor. |
| 38 | GND | power_in | Ground; connect to GND and use as part of the RF input isolation ground next to RF2. |
| 39 | RF2 | input | L5 band RF signal input; DC voltage on this pin must not exceed 0.8V, so a DC-blocking capacitor is needed if the external LNA output carries DC. |
| 40 | GND | power_in | Ground; connect to GND. |
| 41 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | ZHONGKEWEI |
| Package | QFN-40L-EP(5x5) |
| Category | IoT/Communication Modules |
| Pins | 41 |

## Electrical characteristics

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

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| 电源对地电压(VDD_ANA/VDD_BB/DVDD/VDD_BK) |  | -0.3 |  | 1.1 | V |  | 6 |
| 电源对地电压(VDD_IO/VCORE/VBAT/DX_IN) |  | -0.3 |  | 4.1 | V |  | 6 |
| 模拟引脚电压(RTC_O/RTC_I) |  | -0.3 |  | 4.1 | V |  | 6 |
| 射频输入管脚(RF1/RF2) |  | -0.3 |  | 1.1 | V |  | 6 |
| 其他引脚电压 |  | -0.3 |  | 4.1 | V |  | 6 |
| 射频输入功率 |  |  |  | 5 | dBm |  | 6 |
| 结温 |  |  |  | 125 | ℃ |  | 6 |
| 存储温度 |  | -50 |  | 150 | ℃ |  | 6 |
| VDD_IO | VDD_IO | 2.7 | 3.3 | 3.6 | V |  | 6 |
| VBAT | VBAT | 1.4 | 3.3 | 3.6 | V |  | 6 |
| VCore | VCore | 1.2 |  | 3.6 | V |  | 6 |
| DX_IN | DX_IN | 2.7 | 3.3 | 3.6 | V |  | 6 |
| 工作温度 |  | -40 |  | 85 | ℃ |  | 6 |
| RF1 射频输入频率 |  | 1561.1 | 1575.42 | 1602 | MHz |  | 6 |
| TCXO 晶振幅度 |  | 0.5 |  | 1.5 | Vpp | Peak to peak, clipped sine wave | 6 |
| 有源天线短路保护电流 |  | 45 | 50 | 65 | mA |  | 6 |
| 低电平输入电压 | Vil | -0.3 | 0 |  | V |  | 7 |
| 低电平输出电压 | Vol | 0 |  | 0.4 | V |  | 7 |
| 复位电压 |  |  | 1.65 |  | V | @VDD_IO | 6 |
| 复位时间 |  |  | 160 |  | ms |  | 6 |
| TCXO 晶振频率 |  |  | 26 |  | MHz |  | 6 |
| TCXO 晶振电源电压 VX_OUT 输出电压 | VX_OUT |  | 1.8 |  | V |  | 6 |
| 有源天线检测电流 |  |  | 3 |  | mA | VDD_IO=3.3V | 6 |
| 天线检测电路压降 |  |  | 0.3 |  | V | 50mA@VDD_IO=3.3V | 6 |
| 连续运行模式工作电流 |  |  | 25 |  | mA |  | 6 |
| 电池备份电流 |  |  | 30 |  | uA |  | 7 |
| 休眠模式电流 |  |  | 50 |  | uA | ON_OFF=0 | 7 |
| RTC Crystal 频率 |  |  | 32.768 |  | kHz |  | 7 |
| RTC Crystal 等效串联电阻 Rs | Rs |  | 80 |  | kΩ |  | 7 |
| RTC Crystal 串联电容 |  |  | 12.5 |  | pF |  | 7 |
| 漏电流输入管脚 | Ileak |  | 1 |  | uA |  | 7 |
| 上拉电阻 | Rpu |  | 80 |  | kΩ | VDD_IO=3.3V | 7 |
| 下拉电阻 | Rpd |  | 80 |  | kΩ | VDD_IO=3.3V | 7 |

## CAD (KiCad official)

- Symbol: `AT9880B`
- Footprint: `Package_DFN_QFN:QFN-40-1EP_5x5mm_P0.4mm_EP3.6x3.6mm`
- 3D model: QFN-40L-EP(5x5) (KiCad packages3D, STEP)
- 3D model files: `at9880b-etched.step` / `at9880b-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `at9880b.step` / `at9880b.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [ZHONGKEWEI datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8604434706083827712) (16 pp, sha256 `5fe9aedab37df3ec`, retrieved 2026-10-18, 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-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/at9880b-datasheet.pdf)