# WF5803F — Digital Barometer

## Key parameters

- Pressure range: 10 … 1300 hPa
- Package: 8-pin LGA metal-lid
  - Footprint: 6.2 × 6.8 mm²
  - Height: 3.3 mm
- Relative accuracy: ±0.03 hPa (±0.25 m)
- Absolute accuracy: typ. ±1.5 hPa
- Temperature coefficient offset: 1.5 Pa/K (12.6 cm/K)
- Digital interface: I2C / SPI
- Current consumption: 3.5 μA @ 1 Hz sampling rate
- Temperature range: −40 … +125 °C
- RoHS compliant, halogen-free

## Typical applications

- Barometer and altimeter for portable devices
- Indoor and outdoor navigation
- Weather station equipment
- Sport watches
- Flying toys

## 1. Specification (VDD = 3.3 V, T = 25 °C, unless otherwise noted)

| Parameter | Symbol | Condition | Min | Typ | Max | Units |
|---|---|---|---:|---:|---:|---|
| Operating temperature range | T_op | operational | −40 | 25 | +125 | °C |
| Operating temperature range | — | full accuracy | 0 | — | 65 | °C |
| Operating pressure range | P | full accuracy | 10 | — | 1300 | hPa |
| Sensor supply voltage | VDD | — | 1.8 | — | 3.6 | V |
| Interface supply voltage | VDDIO | — | 1.8 | — | 3.6 | V |
| Supply current | I_DD,LP | 1 Hz, ultra low power | — | 3.4 | — | μA |
| Peak current during pressure measurement | I_peak | — | — | 1950 | — | μA |
| Current at temperature measurement | I_DDT | — | — | 900 | — | μA |
| Sleep current | I_DDSL | 25 °C | — | 0.1 | 0.3 | μA |
| Relative accuracy | A_rel | 700…900 hPa, VDD=3.3 V, 25…40 °C | — | ±0.03 | — | hPa |
| Relative accuracy | — | 700…900 hPa, VDD=3.3 V, 25…40 °C | — | ±0.25 | — | m |
| Offset temperature coefficient | TCO | 900 hPa, 25…40 °C | — | ±1.5 | — | Pa/K |
| Offset temperature coefficient | — | 900 hPa, 25…40 °C | — | ±12.6 | — | cm/K |
| Absolute accuracy (pressure) | A_abs | 10…1300 hPa, −20…0 °C | — | ±2.0 | — | hPa |
| Absolute accuracy (pressure) | A_abs | 10…1300 hPa, 0…60 °C | — | ±1.5 | — | hPa |
| Resolution of output data in ultra high resolution mode (Pressure) | — | — | — | 0.025 | — | Pa |
| Resolution of output data in ultra high resolution mode (Temperature) | — | — | — | 0.01 | — | °C |
| Noise in pressure | Vp,full | Full bandwidth, ultra high resolution | — | 1 | — | Pa |
| Noise in pressure | — | Full bandwidth, ultra high resolution | — | 8 | — | cm |
| Noise in pressure | Vp,filtered | Lowest bandwidth, ultra high resolution | — | 0.2 | — | Pa |
| Noise in pressure | — | Lowest bandwidth, ultra high resolution | — | 1.7 | — | cm |
| Absolute accuracy (temperature) | A_T | @25 °C | — | ±0.5 | — | °C |
| Absolute accuracy (temperature) | A_T | 0…+65 °C | — | ±1.0 | — | °C |
| PSRR (DC) | PSRR | Full VDD range | — | ±0.005 | — | Pa/mV |
| Long term stability | ΔP_stab | 12 months | — | TBD | — | hPa |
| Solder drifts | — | — | −0.5 | — | +2 | hPa |

## 2. Absolute maximum ratings

| Parameter | Symbol | Condition | Min | Max | Units |
|---|---|---|---:|---:|---|
| Supply voltage | VDD | — | −0.3 | +3.6 | V |
| Voltage at all IO pins | VDDIO | all pins | −0.3 | VDD + 0.3 | V |
| Overpressure | P | — | 0 | 10,000 | hPa |
| Storage temperature | T_STOR | — | −45 | +150 | °C |
| ESD rating | ESD | HBM | — | ±2 | kV |

## 3. Operation

### 3.1 Brief description

The WF5803F is designed to be connected directly to an external microcontroller via the I2C or SPI bus. Pressure and temperature data has to be compensated by the calibration data of the on-chip Non-Volatile Memory (NVM) which is individually factory calibrated for each device.

### 3.2 Function description

The WF5803F consists of a piezo-resistive micro-machined pressure sensor, an analog to digital converter and a control unit with Non-Volatile Memory (NVM) and a serial I2C/SPI interface. The WF5803F delivers the uncompensated values of the pressure and the temperature. The individual calibration data are stored in NVM. This is used to compensate sensitivity, offset, temperature dependence and other parameters of the sensor.

### 3.3 Measurement of pressure and temperature

The microcontroller sends I2C/SPI write register to start a pressure or temperature measurement. After converting time or checking status via the I2C/SPI, the result value can be read via the I2C/SPI interface. For pressure and temperature calibration calculation in micro-controller, the calibration data in NVM has to be used. The constants can be read out from the WF5803F’s NVM via the I2C/SPI interface at software initialization.

### 3.4 Timing of the measurements

The output data rate (ODR) of the measurements is controlled by the external microcontroller. A single measurement is performed according to the received I2C/SPI register value. When the measurement is finished, the sensor returns to sleep mode and the measurement results can be obtained via I2C/SPI interface.

The ODR can be increased to more than 500 samples per second for dynamic measurement. For application with high ODR, constant t_delay is recommended as the self-heating of the pressure sensor and heat dissipation are in the balance if sampling rate is constant, which helps reducing the noise caused by irregular heat exchange between the sensor and the ambient environment.

## 4. Registers (normal register map)

| Addr | Name | R/W | Notes (as labeled in table) |
|---:|---|:---:|---|
| 0x00 | SPI_Ctrl | RW | SDO_active / LSB_first / Softreset |
| 0x01 | Part_ID | R | PartID<7:0> |
| 0x02 | Status | R | Error_code<3:0> / DRDY |
| 0x06 | DATA_MSB | R | Data out<23:16> |
| 0x07 | DATA_CSB | R | Data out<15:8> |
| 0x08 | DATA_LSB | R | Data out<7:0> |
| 0x09 | TEMP_MSB | R | Temp out<15:8> |
| 0x0A | TEMP_LSB | R | Temp out<7:0> |
| 0x30 | CMD | RW | Sleep_time<3:0> / Sco / Measurement<2:0> |

## 5. SPI interface (timing + instruction format)

### SPI timing parameters

| Symbol | Parameter | Condition | Min | Max | Unit |
|---|---|---|---:|---:|---|
| f_sclk | Clock frequency | max load on SDA/SDO = 25 pF | — | 10 | MHz |
| t_sclk_l | SCLK low pulse | — | 20 | — | ns |
| t_sclk_h | SCLK high pulse | — | 20 | — | ns |
| t_sdi_setup | SDI setup time | — | 20 | — | ns |
| t_sdi_hold | SDI hold time | — | 20 | — | ns |
| t_sdo_od | SDO/SDI output delay | load = 25 pF | — | 30 | ns |
| t_sdo_od | SDO/SDI output delay | load = 250 pF | — | 40 | ns |
| t_csb_setup | CSB setup time | — | 20 | — | ns |
| t_csb_hold | CSB hold time | — | 40 | — | ns |

### Instruction header

The instruction header is 16 bits. It includes:
- R/W bit (read or write)
- W1:W0 bits (data byte count selection)
- register address field (13 bits)

W1:W0 selection:

| W1:W0 | Action |
|---|---|
| 00 | 1 byte |
| 01 | 2 bytes |
| 10 | 3 bytes |
| 11 | 4 bytes (CSB stalling not allowed) |

## 6. I2C interface

The I2C bus uses SCL and SDA as signal lines. Both lines are connected to VDDIO externally via pull-up resistors.

### I2C device address

A7 A6 A5 A4 A3 A2 A1 W/R  
1  1  0  1  1  0  SDO/ADDR  0/1

The LSB bit of the 7-bit device address is configured via the SDO/ADDR pin.

### Electrical specifications of the I2C interface

| Symbol | Parameter | Min | Max | Unit |
|---|---|---:|---:|---|
| f_scl | Clock frequency | — | 400 | kHz |
| t_LOW | SCL low pulse | 1.3 | — | us |
| t_HIGH | SCL high pulse | 0.6 | — | us |
| t_SUDAT | SDA setup time | 0.1 | — | us |
| t_HDDAT | SDA hold time | 0.0 | — | us |
| t_SUSTA | Setup time for a repeated start condition | 0.6 | — | us |
| t_HDSTA | Hold time for a start condition | 0.6 | — | us |
| t_SUSTO | Setup time for a stop condition | 0.6 | — | us |
| t_BUF | Time before a new transmission can start | 1.3 | — | us |

Start condition: SCL is high and SDA has a falling edge. Then the slave address is sent. After the 7 address bits, the direction control bit R/W selects the read or write direction.

## 7. Package / pin configuration

(8-pin metal-lid LGA package; footprint 6.2 × 6.8 mm²; height 3.3 mm)

| Pin | Name | Function |
|---:|---|---|
| 1 | SCLK | Serial data clock |
| 2 | GND | Ground |
| 3 | CSB | Chip select |
| 4 | NC | Not connected |
| 5 | VDD | Positive supply voltage |
| 6 | NC | Not connected |
| 7 | SDA | Serial data (I2C SDA / SPI SDA) |
| 8 | SDO | SDO/ADDR |

## 8. Soldering recommendation (Pb-free)

| Profile feature | Pb-free |
|---|---|
| Average ramp-up rate (TsMax to TP) | 3 °C/s max |
| Preheat: Temperature Min (TsMin) | 150 °C |
| Preheat: Temperature Max (TsMax) | 200 °C |
| Preheat: Time (TsMin to TsMax) | 60 s to 180 s |
| Time maintained above: Temperature (TL) | 217 °C |
| Time maintained above: Time (tL) | 60 s to 150 s |
| Peak temperature (TP) | 260 °C |
| Time within 5 °C of actual peak temperature (TP) | 20 s to 40 s |
| Ramp-down rate | 4 °C/s max |
| Time 25 °C to peak temperature | 8 minutes max |

