YB1211 YOBON | Alldatasheet

Document overview

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Technical content

Features

  • 1.235V Internal Reference Voltage
  • Adjustable Output Voltage : 1.22~5.0V
  • Low-Noise and Low-Drop-Out
  • Typical Output Current : 300mA
  • Low Quiescent Current: ~60μA
  • 320mV Dropout at 300mA 3.3V Output
  • Stable with 1.0μF Ceramic Capacitor
  • Only Need Input and Output Capacitors
  • Thermal Protection Shutdown
  • Output Short-Circuit Current Limit
  • Built-In Internal Soft-Start
  • Green Package (RoHS) Available

Applications

  • PDA, Notebook, PC Computers
  • DSC, Handset Camera Modules
  • PCMCIA Cards, PC Cameras
  • USB Based Portable Devices
  • GSM/GPRS/3G RF Transceiver
  • Wireless LANs
  • Bluetooth Portable Radios
  • Battery-Powered Devices

300mA External Adjustable LDO Regulator Pin Name Pin Function VIN Unregulated Input Supply. Bypass with a capacitor to GND. GND Ground pin. EN Chip enable, pull hi gh to enable the regulator. ADJ Adjustable feedback voltage. The output voltage is set by the external pair of resistors R1 and R2 and the output voltage is calculated by : VOUT = 1.235 * (1 + R1/R2) Volts VOUT Regulated Output Voltage. By pass with a capacitor to GND. Pin Configuration Pin Description Table 1

300mA External Adjustable LDO Regulator

Ordering Information

Recommended Operating Conditions

300mA External Adjustable LDO Regulator

Electrical Characteristics

Function Parameter Conditions Min Typ Max Units Input Voltage Range 2.0 6.0 V Output Voltage External adjustable 1.235 5.0 V Internal Reference Voltage IOUT = 10mA 1.210 1.235 1.260 V Output Current Limit Short-circuit output 300 mA Vout = 5.0V, Iout = 300 mA 250 Vout = 3.0V, Iout = 300 mA 350 Vout = 2.0V, Iout = 300 mA 480 Vout = 1.5V, Iout = 300 mA 700 Dropout Voltage (Note 1) Vout = 1.2V, Iout = 300 mA 850 mV Ground Current Iground = Iin - Iout 60 μA Line Regulation Vin = (Vout + 1V) to 6V, Iout = 10 mA 0.42 %/V Load Regulation Iout = 1mA to 300 mA 1.0 % Shutdown Supply Current EN = 0.4V 0.01 μA f = 1KHz, Iout = 1 mA 50 f = 10KHz, Iout = 1 mA 45 Ripple Rejection (PSRR) f = 100 KHz, Iout = 1 mA 27 dB Start Up Delay (Note 2) Rload=100ohm 20 50 μS EN Logic Low Level Vin = 2.0V to 6.0V 0.4 V EN Logic High Level Vin = 2.0V to 6.0 V 1.2 Vin V EN Input Bias Current Vin = EN = Vout + 1V 0.01 μA Thermal Shutdown Shutdown Temperature 160 °C Thermal Hysteresis 20 °C TA = 25℃, VIN = ( VOUT + 1 V ), CIN = COU T = 1.0μF, VEN = VIN, unless otherwise noted Note1 : The drop out voltage varies depending on output voltage selection. Dropout is defined as VIN–VOUT when VOUT is 100mV below VOUT where Vin=Vout + 1V for nominal VOUT. Note 2: Time needed for VOUT to reach 90% of final value.

300mA External Adjustable LDO Regulator Typical Characteristics At TA=25℃, VIN=(VOUT+1V), CIN=COUT=1.0μF, VEN=VIN, unless otherwise noted.

300mA External Adjustable LDO Regulator

300mA External Adjustable LDO Regulator Functional Block Diagram Functional Description The YB1211 is an low-noise, low-quiescent current, low-dropout linea r regulator. It is supplied in a small SOT-25 package for different applications. YB1211 can supply loads up to 300mA (typical operation, not maximum) and the output voltage are adjustable by a pair of resistor net (R1 and R2 in Figure 3), ranging from 1.22V to 5.0V. As shown in the Functional Block Diagram, the YB1211 consists of a reference and an error amplifier, a big output drive transistor, thermal sensor, and short circuit current limiter. The feedback voltage is acquired from the exte rnal voltage divider through pin ADJ. The internal reference is connected to the error amplifier’s inverting input. The error amplifier compares this reference with the feedback voltage and amplifies the difference. If the feedba ck voltage is lower than the reference voltage, the gate of the pass-transistor 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 gate of the pass transistor is pulled high, allowing less current to pass to the output. Stability The YB1211 is a high performance LDO emphasizing stability with low output capacitance. It is able to maintain stability with an output capacitor as low as 1.0 uF. The output capacitor can also be increased to optimize performance. The YB1211 will remain stable and in regulation with no load, unlike many other voltage regulators. Internal P-Channel Pass Transistor

300mA External Adjustable LDO Regulator The YB1211 features a low impedance P-channel MOSFET pass transistor. This provides several advantages over similar designs using a PNP pass transistor, including low operating power and longer battery life. The YB1211 consumes only 60µA of quiescent current under most conditions. Output Short-Circuit Current Limit The YB1211 includes a current limiter, which monitors and controls the pass transistor’s gate voltage, limiting the output current to about 200mA, for example, in a short-circuit output situation. Shutdown The YB1211 also features 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 de-energize the load. In the shutdown mode, the in ternal functional blocks, such as voltage reference and the error amplifier, are turned off completely, and the quiescent current is less than 1µA. Thermal Protection Shutdown The thermal protecti on shutdown function protects the device from operating in over temperature condition. When the junction temperature exceeds +160°C, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the IC to cool down. The thermal sensor turns the pass transistor on again after the IC’s junction temperature drops to +140°C. Soft-Start Circuitry The YB1211 includes a soft-start circuitry to limit inrush current at turn-on. During power up, the output capacitor and output load are charged with a reduced output current. Shortly after the initial power up, the soft-start feature is terminated and normal operation is resumed.

Application Information

The YB1211 comes with an active-high enable pin that allows the regulator to be enabled. Forcing the enable pin low disables the regulator and puts it into the shutdown mode. This pin cannot be left floating as it may cause an undetermined state. Input/Output Capacitor It is recommended to use a 1.0µF capacitor on the YB1211 input and a 1.0µF capacitor on the output. For high regulation performance, larger input capacitor values and lower ESRs provide better noise rejection and line-transient response. The output noise, load-transient response, stability, and power-supply rejection can be improved by using large output capacitors. Low ESR ceramic capacitors provide optimal performance and save space. Low Output Voltage Application For low output voltage of 1.5V below, YB1211 might show slight oscillation under 50mA loading. In order to stabilize YB1211 output voltage, it is recommended to add a 0.1uF capacitor between VOUT pin and ADJ pin as demonstrated as below :

300mA External Adjustable LDO Regulator