LM9036DTX-3.3

LM9036DTX-3.3 application field and working principle

The LM9036DTX-3.3 is a three-terminal low dropout (LDO) voltage regulator from Linear’s family of Primarily Monitored Integrated Circuit (PMIC) – Voltage Regulators - Linear. This device is designed to provide a regulated output voltage up to 3.3V with low noise, low drop-out voltage, and fast transient response which is suitable for demanding applications such as portable communication devices. Its internal circuitry is made up of a precision band gap reference, metal-oxide field-effect transistor (MOSFET) pass element, current limiting, thermal shutdown and output ESD protection, which will be discussed below.

Application Field

The primary application field for the LM9036DTX-3.3 is low voltage systems such as portable communication devices like mobile phones and digital cameras. It is also suitable for power supply and battery powered systems such as point-of-load (POL) converters, microprocessor (MPU) core power regulators, and microsubsystems.

Features

The LM9036DTX-3.3 comes with a host of features to meet the demands of low noise and fast transient response that are typically required for such applications. These features include:

• A wide operating input range of 3V to 5.5V
• An output range of 1.8V to 3.3V with an output voltage range of typically 4.s%
• High power supply rejection of typically 50dB at 10Hz
• Low dropout voltage of typically 0.3V at full load
• Low quiescent current of typically 80uA
• Fast transient response of typically 1ms
• Thermal protection with a maximum junction temperature of 125°C
• Tight line regulation of typically 0.2%
• Precision band-gap reference with an output current of 2mA

Working Principle

The LM9036DTX-3.3 operates on the basic principles of voltage regulation. It achieves this stabilization by using a feedback loop and a reference voltage, generated internally with its precision band-gap reference. This loop works to sense any changes in output voltage and to adjust the current through the pass element accordingly.

The output voltage of the LM9036DTX-3.3 is set by the external resistors, which must be connected in series between the voltage divider pins provided. A change in the resistors’ value will result in a variation in the applied voltage on the output pins. When the voltage at the output pins is lower than the reference voltage, the pass element becomes more conductive allowing an increased current flow which increases the output voltage. On the other hand, when the voltage at the output pins is higher than the reference voltage, the pass element becomes less conductive restricting the current flow which reduces the output voltage.

The device also features current limiting and thermal protection. The current limiting protects both the device and the circuit in case of too high load demands. The device has an internal protect circuit, which senses any over current conditions, and shuts the device off when it is detected. The thermal protection prevents the device from overheating by monitoring the junction temperature. When the temperature reaches the maximum limit of the junction, the device will automatically shutdown.

Conclusion

The LM9036DTX-3.3 is an ideal voltage regulator for low voltage applications such as portable communication devices. It features a wide input voltage range, low drop-out voltage, low quiescent current, fast transient response, and thermal protection. The device is also protected against over current and output ESD. Its output voltage is set with external resistors, and stabilized by its precision band-gap reference and a feedback loop.