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| YB1211 300mA External Adjustable LDO Regulator Description The YB1211 is a low-noise, low dropout (LDO) linear regulator with enable function and external adjustable output voltage. It operates at an input supply of 2.0~6.0V and is able to output voltages ranging from 1.23V (The YB1211 internal reference voltage) to 5V by a feedback from a pair of resistor divider. The YB1211 regulators are optimized to work with low-ESR and low cost ceramic capacitors, reducing the amount of board space critical in portable devices. The YB1211 requires only 1.0F output capacitor for stability with a load up to 300mA and consumes less than 1A in shutdown mode. Built-in thermal shutdown and short-circuit protect offer secure protection against fault operation. The YB1211 regulators are available in a small SOT-25 package. 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: ~60A 320mV Dropout at 300mA 3.3V Output Stable with 1.0F 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 Typical Application Circuitry YB1211 MRev. 1.0 www.yobon.com.tw 1 YB1211 300mA External Adjustable LDO Regulator Pin Configuration Pin Description Table 1 Pin Name VIN GND EN Pin Function Unregulated Input Supply. Bypass with a capacitor to GND. Ground pin. Chip enable, pull high to enable the regulator. 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 Regulated Output Voltage. Bypass with a capacitor to GND. ADJ VOUT YB1211 MRev. 1.0 www.yobon.com.tw 2 YB1211 300mA External Adjustable LDO Regulator Ordering Information Marking Information Absolute Maximum Ratings Supply Voltage ................................................ -0.3V to 7.0V Output Voltage ....................................... -0.3V to (VIN+0.3V) Output Short-Circuit Duration.....................................Infinite Junction Temperature Range ...................................+150 Storage Temperature Range..................... -65 to +150 Lead Temperature ....................................................+250 Recommended Operating Conditions Input Supply Voltage.........................................2V to 6.0V Operating Temperature............................ -40 to +85 ESD Susceptibility (HBM)...........................................2KV ESD Susceptibility (MM)........................................... 200V Thermal Information Thermal Resistance of Junction to Case (SOT-25, JC) ...........................................................................140 C/W Thermal Resistance of Junction to Ambient (SOT-25, JA) .......................................................................280 C/W Internal Power Dissipation (SOT-25, PD) ..................................................................................................... 400mW YB1211 MRev. 1.0 www.yobon.com.tw 3 YB1211 300mA External Adjustable LDO Regulator Electrical Characteristics Table 2 Function Parameter Input Voltage Range Output Voltage Internal Reference Voltage Output Current Limit External adjustable IOUT = 10mA Short-circuit output Vout = 5.0V, Iout = 300 mA Vout = 3.0V, Iout = 300 mA Dropout Voltage (Note 1) Vout = 2.0V, Iout = 300 mA Vout = 1.5V, Iout = 300 mA Vout = 1.2V, Iout = 300 mA Ground Current Line Regulation Load Regulation Shutdown Supply Current Iground = Iin - Iout Vin = (Vout + 1V) to 6V, Iout = 10 mA Iout = 1mA to 300 mA EN = 0.4V f = 1KHz, Iout = 1 mA Ripple Rejection (PSRR) f = 10KHz, Iout = 1 mA f = 100 KHz, Iout = 1 mA Start Up Delay (Note 2) EN Logic Low Level EN Logic High Level EN Input Bias Current Thermal Shutdown Thermal Hysteresis Rload=100ohm Vin = 2.0V to 6.0V Vin = 2.0V to 6.0 V Vin = EN = Vout + 1V Shutdown Temperature 1.2 0.01 160 20 TA = 25, VIN = ( VOUT + 1 V ), CIN = COU T = 1.0F, VEN = VIN, unless otherwise noted Conditions Min 2.0 1.235 1.210 Typ Max 6.0 5.0 Units V V V mA 1.235 300 250 350 480 700 850 60 0.42 1.0 0.01 50 45 27 20 1.260 mV A %/V % A dB 50 0.4 Vin S V V A C C 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. YB1211 MRev. 1.0 www.yobon.com.tw 4 YB1211 300mA External Adjustable LDO Regulator Typical Characteristics At TA=25, VIN=(VOUT+1V), CIN=COUT=1.0F, VEN=VIN, unless otherwise noted. YB1211 MRev. 1.0 www.yobon.com.tw 5 YB1211 300mA External Adjustable LDO Regulator YB1211 MRev. 1.0 www.yobon.com.tw 6 YB1211 300mA External Adjustable LDO Regulator Functional Block Diagram Functional Description The YB1211 is an low-noise, low-quiescent current, low-dropout linear 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 external 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 YB1211 MRev. 1.0 difference. If the feedback 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 www.yobon.com.tw 7 YB1211 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 60A 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 internal functional blocks, such as voltage reference and the error amplifier, are turned off completely, and the quiescent current is less than 1A. Thermal Protection Shutdown The thermal protection shutdown function protects the device from operating in over temperature condition. When the junction temperature exceeds +160C, 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 +140C. 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 Enable/Shutdown 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 1.0F capacitor on the YB1211 input and a 1.0F 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 : YB1211 MRev. 1.0 www.yobon.com.tw 8 YB1211 300mA External Adjustable LDO Regulator SOT-25 Package Information YB1211 MRev. 1.0 www.yobon.com.tw 9 |
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