The DS2438 allows interpreting its data according to several internal registers. Here are the main formulas:

🔹 Temperature

T(°C) = Raw Value / 16

Example:

Raw value = 0x0900 = 2304

T = 2304 / 16 = 144 °C

✅ Result: 144 °C (high temperature test example).

🔹 Voltage (VAD or VDD)

V = (ADC value / 1024) × 10 V

Example:

ADC Value = 0x190 = 400

V = 400 / 1024 × 10 = 3.91 V

✅ Result: 3.91 V measured on the analog input.

🔹 Current (VSENS)

With an external shunt resistor Rsh = 0.05 Ω :

I (A) = V_sense / R_sh I = 0.025 / 0.05 = 0.5 A

✅ Result: measured current = 0.5 A.

🔹 Practical notes:

The DS2438 can simultaneously measure the voltage of a battery (VDD), the internal temperature, and the current flowing through a sense resistor.

The conversion registers (Page 0 → 3) contain all the raw data accessible via the 1-Wire bus.

The DS2438 connects via a standard 1-Wire bus, while also having additional analog terminals to measure voltage and current.

🔹 Typical components

🔹 Functional diagram (ASCII)

         +3.3V / +5V
              │
             [4.7kΩ]
              │
DATA ─────────┼──────────────┐
              │              │
             GND           DS2438
                          ┌────────────┐
                          │ VDD  → Measure tension
                          │ VAD  → Analog input
                          │ VS+  → Current +
                          │ VS−  → Current −
                          │ GND  → Mass
                          └────────────┘

💡 The VS+ and VS− terminals frame the shunt resistor (0.05 Ω) used for current measurement.

🔹 Operating principle

1️⃣ The microcontroller queries the DS2438 via the 1-Wire bus.

2️⃣ The sensor sequentially performs:

• the internal temperature measurement,
• the reading of VDD/VAD,
• the differential measurement VS+ / VS−.

3️⃣ The data is then converted and can be stored in the internal EEPROM.