The YB1230 is a series of low noise, low loss (LDO) linear regulators with 2.0% output voltage accuracy. The YB1230 regulator can achieve a low voltage drop of 500mV at a load current of 600mA from a 3.1V output, with a voltage range from 1.8V to 3.1V, 0.1V per stage (custom voltages are considerable on request). The YB1230 regulator is optimized for use with low ESR and low cost ceramic capacitors, reducing critical board space in handheld devices. The yb1230 requires only a 2.2µf output capacitor for stable operation under any load and consumes less than 1µA in shutdown mode. Built-in thermal shutdown and short circuit protection provide safe fault operation protection. The YB1230 regulator is available in SOT-23 /SOT-25/SOT-89 packages.
Typical Application Circuit

Features 2.0% Accurate Output Voltage Output Voltage Range 1.8V~3.1V Low Noise Low Loss Stable, 2.2μF Ceramic Capacitor Suitable for Any Load Typical Output Current: 600mA Low Quiescent Current: About 90μA at 600mA Load (3.1V) 500mV loss; only input and output capacitors are needed for power saving shutdown mode (<1μA) thermal protection shutdown Built-in internal soft-start output short circuit current limit protection Green package (RoHS) available for applications PCMCIA card, PC camera USB-based portable device (MP3, PMP) GSM/GPRS/3G RF transceiver module Wireless LAN Bluetooth portable radio YB1230 is a low noise, low quiescent current, low loss linear regulator. It is available in SOT-23/SOT-25/SOT-89 packaging for different applications. These devices can provide loads of up to 600 mA. As shown in the functional block diagram, the YB1230 consists of a reference and noise bypass circuit, an error amplifier, an output drive transistor, an internal feedback voltage divider, a thermal sensor, and a short-circuit current limiter. The internal reference is connected to the inverting input of the error amplifier. The error amplifier compares this reference voltage to the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass transistor gate is pulled low. This allows more current to pass to the output and increases the output voltage. If the feedback voltage is too high, the pass transistor gate is pulled high, allowing less current to be passed to the output. The output voltage of these devices varies from 1.8v to 3.1v. Stability The yb1230 is a high performance ldo that emphasizes stability with low output capacitance. The output capacitance is as low as 2.2uf and can remain stable. The output capacitance can also be increased to optimize performance. Unlike many other voltage regulators, the YB1230 will maintain stable and no-load regulation. The internal p-channel pass transistor yb1230 has a low impedance p-channel mosfet pass transistor. This offers several advantages over similar designs using PNP transistors, including lower operating power and longer battery life. In most cases, the YB1230 consumes only 90 microamps of quiescent current. Output Short Circuit Current Limit The yb1230 includes a current limiter that monitors and controls the gate voltage across the transistor, limiting the output current to approximately 380ma, for example in a short circuit output condition. Shutdown The YB1230 also has a low-power active shutdown mode. It has a switch that turns off the device when disabled. This allows the output capacitor and load to discharge and power down the load. In shutdown mode, the internal functional blocks, such as the voltage reference and error amplifier, are completely shut down and the quiescent current is less than 1 µA. Thermal Shutdown The thermal shutdown function prevents the device from working in over-temperature conditions. When the junction temperature exceeds +160 °C, the thermal sensor sends a signal to the shutdown logic, which turns off the pass transistor, allowing the IC to cool. After the IC's junction temperature drops to +140°C, the thermal sensor turns on the pass-through again. Soft-start circuit YB1230 includes a soft-start circuit to limit the inrush current at turn-on. At power-up, the output capacitor and output load are charged with a reduced output current. Shortly after initial power-up, the soft-start function terminates and normal operation resumes. Application Information Enable/Disable The YB1230 has an active high enable pin that allows the regulator to be enabled. Forcing the enable pin low will disable the regulator and put it into shutdown mode. This pin cannot be left floating as it can lead to an undetermined state. Input/Output Capacitor It is recommended to use a 2.2μF capacitor at the YB1230 input and a 2.2μF capacitor at the output. For high regulation performance, larger input capacitor values and lower esr provide better noise rejection and line transient response. Using bulk output capacitors can improve system output noise, load transient response, stability, and power supply rejection. Low esr ceramic capacitors provide optimum performance and space savings.