P9242-R Datasheet

© 2016 Integrated Device Technology, Inc

17

December 16, 2016

7.10 Step-Down Regulator

The input capacitors (C14 and C15 in Figure 24) must be connected as close as possible between the VIN pin and GND pin. Similarly, the

output capacitor (C4 and C5 in Figure 24) must be placed close to the inductor and GND. The output voltage is sensed by the VIN_LDO pin;

therefore, the connection from the step-down output (VCC_5V; see Figure 24) to the VIN_LDO pin should be made as wide and short as

possible to minimize output voltage errors. The step-down regulator is the input voltage to the LDO18 and LDO33 linear regulators and is not

recommended for powering an external load.

The P9242 has three low-dropout (LDO) regulators used to bias the internal circuitry. The 5V pre-regulator (PREG) provides bias for the

entire internal power management. The PREG requires a 1μF ceramic bypass capacitor connected from the PREG pin to GND. This

capacitor must be placed very close to the PREG pin. The voltage regulator must not be externally loaded.

The LDO33 and LDO18 are used to bias the internal digital circuit. The regulator’s input voltage is supplied through the VIN_LDO pin. Both

regulators require a 1μF ceramic capacitor from the pin to GND. The voltage regulators must not be externally loaded.

7.12 Under-Voltage Lock-Out (UVLO) Protection

The P9242-R has 4V (typical, rising) under-voltage lockout circuit on the VIN pin. To guarantee proper functionality, the voltage on the VIN pin

must rise above the UVLO threshold. If the input voltage stays below the UVLO threshold, the P9242-R is in Shut Down Mode.

Figure 17. UVLO Threshold Definition

Shut

Down

Mode

Shut

Down

Mode

Normal

Operating

Mode

Time

specific, and it must comply with the WPC recommendation. The WPC recommendations include the self-inductance value, DC resistance

(DCR), Q-factor, size, and number of turns.

are highly recommended for their AC and DC characteristics and temperature stability. The recommended parts are listed on the bill of

materials (BOM) in Table 15.