DESCRIPTION The YB1210 series consists of a series of 300mA ultra-low noise, low loss (LDO) linear regulators designed specifically for battery powered RF and wireless applications. The YB1210 regulator achieves a low voltage drop of 450mV at 250MA load current at 3.3V output, ultra-low output voltage noise of 15μVRMS and PSRR of 57dB at 1KHz.
The YB1210 regulator is also optimized for use with low ESR and low cost ceramic capacitors, reducing critical board space in handheld devices. YB1210 only needs 0.47μF output capacitor to work stably under any load. The YB1210 consumes less than 1µA in shutdown mode. Other features include high output voltage accuracy and current limit protection. The YB1210 regulator is available in SOT-23 /SOT-25/SOT-89 packages.
Typical Application Circuit

Features High precision +-2% output voltage, ultra-low noise and low loss regulator, with 1.8/2.5/2.6/2.8/3.0V/3.3V preset output stability, with 0.47μF ceramic capacitor, suitable for any load allowable output current : 300mA Low Quiescent Current: About 90μA at 250mA (3.3V) 450mV Loss Only Input and Output Capacitors Power Saving Shutdown Mode (<1μA) Thermal Shutdown Built-in Soft Start Output Short Circuit Current Limit Protection Green Package (RoHS) Available Applications PDA, Pocket PC and Notebook Digital Cameras, Cell Phone Camera Modules PCMCIA Cards, PC Cameras USB-based Portable Devices (MP3, PMP) GSM/GPRS/3G RF Transceiver Modules Wireless LAN Bluetooth Portable Radio YB1210 is a An ultra-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 250mA. As shown in the functional block diagram, the YB1210 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 flow through the output. The device has preset output voltages from 1.8v to 3.3v. Stability The yb1210 is a high performance ldo that emphasizes stability with low output capacitance. The output capacitance is as low as 0.47uf and remains stable. The output capacitance can also be increased to optimize performance. Unlike many other voltage regulators, the YB1210 will remain stable and regulate with no load. Internal p-channel pass transistor yb1210 has a low impedance p-channel mosfet pass transistor. This offers several advantages over designs using PNP transistors, including low operating power and longer battery life.

In most cases, the YB1210 consumes only 90 microamps of quiescent current. The output short circuit current limit yb1210 includes a current limiter that monitors and controls the gate voltage of the pass transistor, for example limiting the output current to about 200ma in the case of a short circuit output. Shutdown YB1210 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, 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 feature protects the device from over-temperature conditions. When the junction temperature exceeds +160°C, the thermal sensor signals the shutdown logic to turn off the pass transistor and allow the IC to cool. When the junction temperature of the IC drops to +140°C, the thermal sensor turns on the pass tube again. Soft-Start Circuit The YB1210 includes a soft-start circuit to limit the inrush current at turn-on. When the weight period is 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 YB1210 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 0.47μF capacitor at the YB1210 input and a 0.47μF 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. Power Supply Rejection and Transient Response The psrr and transient response can be improved by increasing the value of the input and output bypass capacitors, as well as through passive filtering techniques.