150mA Low-Noise LDO Regulator

Transcription

1 50mA Low-Noise LDO Regulator Product Description The GS265 is an efficient linear voltage regulator with ultra low-noise output, very low dropout voltage (typically 7mV at light loads and 65mV at 50mA), and very low ground current (600uA at 0mA output). The GS265 offers better than % initial accuracy. Designed especially for hand-held, battery-powered devices, the GS265 includes a CMOS or TTL compatible enable/shutdown control input. When shutdown, power consumption drops nearly to zero. Regulator ground current increases only slightly in dropout, further prolonging battery life. GS265 key features include a reference bypass pin to improve its already excellent low-noise performance, reversed-battery protection, current limiting, and over temperature shutdown. The GS265 is available in fixed and adjustable output voltage versions in a small SOT-25 package. GS265 series low-dropout regulators are stable with ceramic output capacitors. Features Ultra-low-noise output High output voltage accuracy Guaranteed 50mA output Low quiescent current Low dropout voltage Extremely tight load and line regulation Very low temperature coefficient Current and thermal limiting Reverse-battery protection Zero off-mode current Logic-controlled electronic enable Applications Cellular telephones Battery-powered equipment SMPS post-regulator/dc-to-dc modules High-efficiency linear power supplies Laptop and notebook computers Consumer/personal electronics Block Diagram IN OUT VOUT IN OUT VOUT BYP COUT COUT CBYP (optional) R EN Current Limit Thermal Shutdown GS265-x.x Bandgap Ref. GND EN Current Limit Thermal Shutdown GS265-ADJ Bandgap Ref. GND ADJ R2 CBYP (optional) VOUT=VREF(+R2/R) Ultra-Low-Noise Fixed Regulator Ultra-Low-Noise Adjustable Regulator

2 Packages & Pin Assignments GS265 (SOT-25) GS265-XX (FIX) Pin # GS265 (ADJ) Pin # Pin Name Pin Function IN Supply Input 2 2 GND Ground 3 3 EN 4 - BYP - 4 ADJ Enable/Shutdown: CMOS compatible input. Logic high = enable, logic low or open = shutdown. Reference Bypass: Connect external 470pF capacitor to GND to reduce output noise. May be left open. Adjustable regulator feedback input. Connect to resistor voltage divider. 5 5 OUT Regulator Output Ordering Information Package Code Voltage Code Pb Free Code *For other voltages, please contact factory. GS 265 L xx F GS Brand Name Part Number Marking Information Date Code GS Code BB 4 VYW G GS P/N Voltage Code Part Number Marking Output GS265L BBA WYG ADJ GS265L25 BBH WYG 2.5V GS265L30 BBQ WYG 3.0V GS265L33 BBR WYG 3.3V GS265L50 BBV WYG 5.0V 2

3 Absolute Maximum Ratings Parameter Symbol Ratings Units Supply Input Voltage V IN -20 to +20 V Enable Input Voltage V EN -20 to +20 V Power Dissipation (Internally Limited) P D SOT-25 5 W Thermal Resistance Junction to Ambient () θ JA SOT /W Junction Temperature T J -40 to +25 C Storage temperature T STG -65 to +50 C Lead Temperature (Soldering, Seconds) T LEAD 260 C Electrical Characteristics V IN =V OUT +V; I L =0uA; C L =.0uF; V EN 2.0V; T J =25 C, bold values indicate 40 C T J +25 C; unless noted. Symbol Parameter Condition Min Typ Max Unit V O Variation from specified - Output Voltage Accuracy (Note 9) V OUT -2 2 % V O / T Output Voltage Temperature Coefficient (Note 4) 40 ppm/ V O / V O Line Regulation VIN = VOUT + V to 6V % / V V O / V O Load Regulation IL = 0. to 50mA, (Note 5) 0.5 % IL = 0uA V IN - V O Dropout Voltage, (Note 6) IL = 50mA mv IL = 0mA IL = 50mA I GND Quiescent Current V EN 0.4V (shutdown) V EN 8V (shutdown) 5 ua VENV/ 2.0V, IL = 0uA I GND IL = 50mA Ground Pin Current, 800 ua (Note 7) IL = 0mA 500 IL = 50mA PSRR Ripple Rejection Frequency=0Hz IL = 0uA 75 db I LIMIT Current Limit V OUT = 0V ma V O / P D Thermal Regulation (Note 8) 0.05 %/W e NO Output Noise IL = 50mA, CL = 2.2uF, 470pF from BYP to GND

4 Electrical Characteristics (Continue) ENABLE Input Symbol Parameter Condition Min Typ Max Unit V IL V IH I IL I IH Enable Input Logic-Low Voltage Enable Input Logic-High Voltage Enable Input Current Regulator shutdown 0.4 V 8 V Regulator enabled 2.0 V VIL 0.4V - ua VIL 8V -2 ua VIH 2.0V ua VIH 2.0V 25 ua Note : Exceeding the absolute maximum rating may damage the device. Note 2: The device is not guaranteed to function outside its operating rating. Note 3: The maximum allowable power dissipation at any T A (ambient temperature) is P D (max) = (T J (max) T A ) θ JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The θ JA of the GS265LXX (all versions) is 220 /W mounted on a PC board (see Thermal considerations section for further details). Note 4: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 5: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 0. to 50mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. Note 6: Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at Vdifferential. Note 7: Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of the load current plus the ground pin current. Note 8: Thermal regulation is defined as the change in output voltage at a time t after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a 50mA load pulse at V IN =6V for t = ms. Note 9: The GS265-adj has V REF =.23V +/-%, but minimum output voltage for GS265-adj must be above V OUT (min)=2.0v. Typical Application GS265-x.x Enable Shutdown EN EN(pin3) may be connected directly to IN (pin ). Vout C OUT=2.2uF tantalum Low-Noise Operation: C BYP=470pF,COUT 2. 2uF Basic Operation: C BYP=not use,cout uf Ultra-Low-Noise Regulator Application 4

5 Typical Characteristics 0.00 COUT=uF CBYP=nF 0 K K 0mA,Cout=uF Vout=5V 0K M M 0.00 Vout=5V COUT=uF electrolytic 0 K K 0mA 0K ma M M ma 0mA Vout=5V 0.00 COUT=22uF tantalum CBYP=nF 0 K K 0K M M 0mA Vout=5V ma 0.00 COUT=uF electrolytic CBYP=0pF 0 K K 0K M M 0mA 0.00 Vout=5V COUT=uF electrolytic ma CBYP=nF 0 K K 0K M M 0mA Vout=5V ma 0.00 COUT=uF electrolytic CBYP=nF 0 K K 0K M M 5

6 Application Notes Enable/Shutdown Forcing EN (enable/shutdown) high (>2V) enables the regulator. EN is compatible with CMOS logic gates. If the enable/shutdown feature is not required, connect EN (pin 3) to IN (supply input, pin ). See Figure. Input Capacitor A uf capacitor should be placed from IN to GND if there is more than inches of wire between the input and the ac filter capacitor or if a battery is used as the input. Reference Bypass Capacitor BYP (reference bypass) is connected to the internal voltage reference. A 470pF capacitor (C BYP ) connected from BYP to GND quiets this reference, providing a significant reduction in output noise. C BYP reduces the regulator phase margin; when using C BYP, output capacitors of 2.2uF or greater are generally required to maintain stability. The start-up speed of the GS265 is inversely proportional to the size of the reference bypass capacitor. Applications requiring a slow ramp-up of output voltage should consider larger values of C BYP. Likewise, if rapid turn-on is necessary, consider omitting C BYP. If output noise is not a major concern, omit C BYP and leave BYP open. Output Capacitor An output capacitor is required between OUT and GND to prevent oscillation. The minimum size of the output capacitor is dependent upon whether a reference bypass capacitor is used..0uf minimum is recommended when C BYP is not used (see Figure 2). 2.2uF minimum is recommended when C BYP is 470pF (see Figure ). Larger values improve the regulator s transient response. The output capacitor value may be increased without limit. The output capacitor should have an ESR (effective series resistance) of about 5Ωor less and a resonant frequency above MHz. Ultra-low-ESR capacitors can cause a low amplitude oscillation on the output and/or under damped transient response. Most tantalum or aluminum electrolytic capacitors are adequate; film types will work, but are more expensive. Since many aluminum electrolytic have electrolytes that freeze at about 30 C, solid tantalums are recommended for operation below 25 C. At lower values of output current, less output capacitance is required for output stability. The capacitor can be reduced to 0.47uF for current below ma or 0.33uF for currents below. No-Load Stability The GS265 will remain stable and in regulation with no load (other than the internal voltage divider) unlike many other voltage regulators. This is especially important in CMOS RAM keep-alive applications. Thermal Considerations The GS265 is designed to provide 50mA of continuous current in a very small package. Maximum power dissipation can be calculated based on the output current and the voltage drop across the part. To determine the maximum power dissipation of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation: TJ(max) - TA P D (max) = θja T J (max) is the maximum junction temperature of the die, 25 C, and TA is the ambient operating temperature. θ JA is layout dependent; Table shows examples of junction-to-ambient thermal resistance for the GS265. Package θ JA Recommended Minimum Footprint θ JA Square Copper Clad SOT C/W 70 C/W 30 C/W θ JC 6

7 Fixed Regulator Applications GS265-x.x Vout 2.2uF 470pF Figure. Ultra-Low-Noise Fixed Voltage Application Figure includes a 470pF capacitor for low-noise operation and shows EN (pin 3) connected to IN (pin ) for an application where enable/shutdown is not required. C OUT = 2.2uF minimum. GS265-x.x Vout Enable Shutdown EN.0uF Figure 2. Low-Noise Fixed Voltage Application Figure 2 is an example of a low-noise configuration where C BYP is not required. C OUT = uf minimum. Adjustable Regulator Applications The GS265 can be adjusted to a specific output voltage by using two external resistors (Figure 3). The resistors set the output voltage based on the following equation: R2 V OUT =.242V + R This equation is correct due to the configuration of the band gap reference. The band gap voltage is relative to the output, as seen in the block diagram. Traditional regulators normally have the reference voltage relative to ground and have a different VOUT equation. Resistor values are not critical because ADJ (adjust) has a high input impedance, but for best results use resistors of 470kΏ or less. A capacitor from ADJ to ground provides greatly improved noise performance. 7

8 GS265-ADJ Vout 2.2uF R 470pF R2 Figure 3. Ultra-Low-Noise Adjustable Voltage Application Figure 3 includes the optional 470pF noise bypass capacitor from ADJ to GND to reduce output noise. Dual-Supply Operation When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground. 8

9 Package Dimension SOT-25 PLASTIC PACKAGE D e E G E e b L (L) θ A A2 c A Dimensions SYMBOL Millimeters Inches MIN MAX MIN MAX A A A b c D E E e 0.95 (TYP).037 (TYP) e.90 (TYP).075 (TYP) L L 0.60 (TYP).024 (TYP) G 0.25 (TYP).0 (TYP) θ

10 NOTICE Information furnished is believed to be accurate and reliable. However Globaltech Semiconductor assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties, which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Globaltech Semiconductor. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information without express written approval of Globaltech Semiconductor. (Revise Date:2007//3 Version_.0)