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| US1205 300 mA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR PRELIMINARY DATASHEET FEATURES SOT23 package Stable with 2.2uF ceramic capacitor 1% Voltage Reference Accuracy Only 270mV Dropout at 300 mA 170mV Dropout at 150mA 10nA Quiescent Current in Shutdown Current Limit and Thermal Shutdown Logic input Enable pin DESCRIPTION The US1205 device is an efficient linear voltage regulator with better than 1% initial voltage accuracy, very low dropout voltage and very low ground current designed especially for hand held, battery powered applications. Other features of the device are; TTL compatible enable/ shutdown control input, current limiting and thermal shutdown. The US1205 is available in fixed and adjustable output voltage versions in a small SOT23-5 package. APPLICATIONS Laptop, Notebook & Palmtop computers Battery powered Equipments PCMCIA Vcc & Vpp regulator Concumer Electronics High Efficiency Linear Power Supplies TYPICAL APPLICATION Vin C1 2.2uF 1 2 3 Vin Vout 5 R1 C2 2.2uF Vout Gnd R2 Vo=1.242 X (1+R1/R2) S.D. Enable En Adj 4 1205app1-1.1 Typical application of the US1205 ajustable. 3.3V C1 2.2uF 1 2 3 Vin Vout 5 C2 2.2uF 2.5V Gnd S.D. Enable En Byp 4 C3 1000pF 1205app2-1.2 Typical application of the US1205 Fixed voltage. PACKAGE ORDER INFORMATION Tj (C) 0 TO 125 0 TO 125 0 TO 125 0 TO 125 0 TO 125 Rev. 1.4 9/25/00 5 LEAD SOT 23 US1205CL US1205-25CL US1205-30CL US1205-33CL US1205-36CL SOT23 Marking AT00 AT25 AT30 AT33 AT36 Output Voltage Adj 2.5 V 3.0 V 3.3 V 3.6 V 2-1 US1205 ABSOLUTE MAXIMUM RATINGS Input Voltage (Vin) ............................................................. 10V Enable Input Voltage ........................................................... 10V Storage Temperature Range ................................ -65C TO 150C Operating Junction Temperature Range ...................... 0C TO 150C PACKAGE INFORMATION 5 PIN SOT23 ( L ) Adjustable En Gnd Vin 3 2 1 5 PIN SOT23 ( L ) Fixed En Gnd Vin 3 2 1 AT00 4 5 JA=220C/W 4 ATxx 5 JA=220C/W Adj Vout Byp Vout ELECTRICAL SPECIFICATIONS Unless otherwise specified ,these specifications apply over ,Cin=Co=22uF, Io=100uA, Vinmin=2.5V(Adjustable devices) Vin=Vo+1V(for fixed voltage devices), Vout=Vfb (for adjustable version only), Cbyp=470pF(for fixed output versions only), Venb=2V and Ta=25C. Typical values refer to Ta=25 C.Low duty cycle pulse testing are used which keeps junction and case temperatures equal to the ambient temperature. PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS Reference Voltage Vo -1 1 % See Table 1 for typical values (Note 4) -2 2 Line Regulation dVi Vo+1V Rev. 1.4 9/25/00 US1205 Note 1 : Low duty cycle pulse testing with Kelvin connections are required in order to maintain accurate data. Note 2 : Drop-out voltage is defined as the minimum differential voltage between Vin and Vout required to maintain regulation at Vout. It is measured when the output voltage drops 1% below its nominal value. Note 3 : Ground current is the the regulator quiescent current plus the pass transistor current. The total current from the supply is the sum of the load current plus the ground pin current. Note 4 : The specification applies for the junction temperature of 0 to +125C. Pin DescRIPTIONS PIN # 4 4 5 PIN SYMBOL Adj (Adjustable only) Byp (Fixed output only) Vout PIN DESCRIPTION A resistor divider from this pin to the Vout pin and ground sets the output voltage. A 470 to 1000pF bypass capacitor connected to this pin reduces the output noise. The output of the regulator .A minimum of 2.2uF with max ESR of 1 ohm capacitor must be connected from this pin to ground to insure stability. Ground pin. This pin must be connected to the lowest potential in the system & all other pins must be at higher potential with respect to this pin. Enable pin. A low signal or left open on this pin shuts down the output.This pin must be tied HI or to Vin for normal operation. The input pin of the regulator. Typically a large storage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimumdrop out voltage during the load transient response. This pin must always be higher than Vout by at least the amount of the dropout voltage and some margin in order for the device to regulate properly. 2 GND 3 1 En Vin 5 LEAD SOT 23 US1205 US1205-25 US1205-30 US1205-33 US1205-36 Output Voltage 1.242V 2.5 V 3.0 V 3.3 V 3.6 V The output voltage of the adjustable device can be set using: Vo=1.242 X (1+R1/R2) Where; R1=Resistor connected from output to the Adj pin R2=Resistor connected from Adj pin to GND Table 1- Nominal output voltage v.s. part number BLOCK DIAGRAM Vin Vout Vin Vout Adj THERMAL SHUTDOWN Byp 1.242V + 1.242V + THERMAL SHUTDOWN Gnd 1205blk1-1.1 En Gnd 1205blk2-1.0 En Figure 1- US1205 Adjustable block diagram Rev. 1.4 9/25/00 Figure 2- US1205 Fixed output block diagram 2-3 |
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