Dual Input Dropout Regulators

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Dual Input Dropout Regulators Product Description The GS8 is a high performance positive voltage regulator is designed for use in applications requiring very low dropout voltage at amps.

v supplies are available, the superior dropout characteristics of the GS8 result in reduced heat dissipation compared to regular LDOs, thus allowing heat sink size reduction.

Outstanding features include very low dropout performance at rated current, fast transient response, remote sense, internal current limiting, thermal shutdown and safe operating area protection of

1 Dual Input Dropout Regulators Product Description The GS8 is a high performance positive voltage regulator is designed for use in applications requiring very low dropout voltage at amps. When supplying. on motherboards where both and.v supplies are available, the superior dropout characteristics of the GS8 result in reduced heat dissipation compared to regular LDOs, thus allowing heat sink size reduction. Additionally, the GS8 provides excellent regulation over variations in line, load and temperature. Remote sense operation allows compensating for trace, connector and other resistive losses. Outstanding features include very low dropout performance at rated current, fast transient response, remote sense, internal current limiting, thermal shutdown and safe operating area protection of the output device. The GS8 is a five terminal adjustable voltage regulator available in the TO-- and TO-6- packages. Features V OUT Range is. V POWER Dropout =.@A ( C) V CONTROL Dropout =.@A ( C) % Trimmed Reference Remote Voltage Sensing Thermal Shutdown Current Limit Short Circuit Protection Fast Transient Response Very Low Dropout Reduces Total Power Consumption Lead-Free Package is available Applications High Efficiency Linear Regulators Post Regulators for Switching Supplies Microprocessor Supply Adjustable Power Supply Block Diagram VCONTROL Vpower + - Thermal Limit ADJ Vout SENSE GND

2 Packages & Pin Assignments GS8M (TO-6-) GS8D (TO--) (TAB) GS8M-xxF GS8D-xxF Pin Description V SENSE V SENSE ADJ ADJ V OUT V OUT V CONTROL V CONTROL V POWER V POWER Pin # Pin Symbol Function This Pin is the positive side of the reference voltage for this device. With this pin it is V SENSE possible to Kelvin sense the output voltage at the load. Adjust This pin is the negative side of the reference voltage for the device. Transient response can be improved by adding a small bypass capacitor from the adjust pin to ground. V OUT This is the power output of the device, and is electrically connected to the tab. V CONTROL will be approximately % of the output current. For the device to regulate, the voltage at this pin must be between.9v and.v greater than the output voltage (see dropout This pin is the supply pin for the control circuitry for the device. The current flow into this pin specifications). V POWER supplied through this pin. For the device to regulate, the voltage on this pin must be This is the collector input to the power device of the GS8X. The output load current is between.v and.7 greater than the output voltage (see dropout specifications). Ordering Information GS Brand Name Package Code Voltage Code GS8 P xxf Pb Free Code *Adjustable Version does not need Voltage Code. **For other voltages, please contact factory. Part Number TO-- TO-6- Output GS8D GS8M ADJ GS8D GS8M. Marking Information GS P/N Package Code GS8 P VV F YWLG Voltage Code Lead Free Date Code GS Code

3 Absolute Maximum Ratings Parameter Symbol Maximum Rating Units V POWER 7 V Input Voltage V CONTROL V TO-. Power Dissipation (Internally Limited) P D W TO-6 SOT- Thermal Resistance Junction to Ambient θ JA SOT C/W Control Section to C Operating Junction Temperature Range T J Power Transistor to C Storage Temperature Range T STG -6 to C Lead Temperature (Soldering, Sec). T LEAD C Electrical Characteristics at I OUT=mA,and T J=+ C unless otherwise specified. Parameter Device Conditions MIN TYP MAX Unit V CONTROL=.7, V POWER=.7, I LOAD=mA.8..6 V Reference Voltage GS8 *V CONTROL=.7V to V, V POWER=.V to., I LOAD =ma to A...7 V Output Voltage GS8- V CONTROL=.V, V POWER=.V.7.. V *V CONTROL=.V, V POWER=.V, I LOAD=mA to A.6.. V Line Regulation All *I LOAD =ma, (.+V OUT) V CONTROL V,.8V V POWER - V OUT... % Load Regulation All *V CONTROL=V OUT+., V POWER=V OUT+.8V, I LOAD =ma to A.8. % Minimum Load Current (Note) GS8 * V CONTROL=, V POWER=.V, V ADJ=V.7 ma Control Pin Current (Note) All *V CONTROL=V OUT+., V POWER=V OUT+.8V, I LOAD =ma to A 8 ma Ground Pin Current GS8-XX *VCONTROL=VOUT+., V POWER=V OUT+.8V, I LOAD =ma to A ma Adjust Pin Current GS8 *V CONTROL=.7, V POWER=., I LOAD =ma μa Current Limit All *V IN- V OUT=V. 6.8 A Ripple Rejection All V CONTROL=V POWER=V OUT+., V RIPPLE=V P-P, I LOAD=.A 6 7 db Thermal Regulation GS8 T A= C, ms pulse. %/W Control Input (V CONTROL - V OUT) Power Input (V POWER - V OUT) All Dropout Voltage (Note ) *V POWER=V OUT+.8V, I LOAD =ma.. V *V POWER=V OUT+.8V, I LOAD =A.. V All *V CONTROL=V OUT+., I LOAD =A..7 V The * denotes the specifications which apply over the full temperature range. Note : Unless otherwise specified V OUT=V SENSE, For GS8 V ADJ=V. Note : For the adjustable device the minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor divider used to set the output voltage is select to meet the minimum load current requirement. Note : The control pin current is the drive current required for the output transistor. This current will track output current with a ratio of about :. Note : The dropout voltage for the GS8 is caused by either minimum control voltage or minimum power voltage. The specifications represent the minimum input/output voltage required to maintain % regulation.

4 Typical Application Circuits Fixed Voltage Regulator Adjustable Voltage Regulator Control IN Power IN TAB VCONTROL VOUT GS8 VPOWER SENSE GND uf uf 68uF Vout.V uf VCONTROL TAB GS8 VPOWER SENSE ADJ uf V.uF VOUT R % R % LOAD. A uf 7V > VPOWER > (VOUT + dropout Voltage) VOUT =VREF x (+ R / R ) +IADJ x R Typical Performance Characteristics Dropt Voltage (V IN -V OUT ). Minimum Operating Current DROPOUT VOLTAGE(V) TJ= C TJ= C MINMUM OPERATING CURRENT(mA) TJ= C TJ= C TJ= C..... OUTPUT CURRENT(A). 6 7 INPUT/OUTPUT DIFFERENTIAL(V) Short-Circuit Current Load Regulation SHORT CIRCUIT CURRENT (A) TJ= C TJ= C 6 7 INPUT/OUTPUT DIFFERENTIAL(V) OUTPUT VOLTAGE DEVIATION (%).. ILOAD=A TEMPERATURE ( C)

5 Typical Performance Characteristics (Continue) RIPPLE REJECTION(dB) OUTPUT VOLTAGE CHANGE(%) VRIPPLE Ripple Rejection (VIN-VOUT) VP-P VRIPPLE VDROPOUT (VIN-VOUT).P-P V CADJ=uF at f<6hz CADJ=uF at f>6hz IOUT=.A K K K FREQUENCY(Hz) Dropt Voltage(V IN -V OUT ) 7 TEMPERATURE ( C) RIPPLE REJECTION(dB) ADJUST PIN CURRENT(uA) Ripple Rejection vs. Current fripple=hz VRIPPLE fripple=hz VRIPPLE VP-P.P-P VOUT= CADJ=uF COUT=uF OUTPUT CURRENT(A) Minimum Operating Current TEMPERATURE ( C) Application Information The GS8 series of adjustable and fixed regulators are designed to power the new generation of microprocessors. The GS8 is designed to make use of multiple power supplies, present in most systems, to reduce the dropout voltage. One of the advantages of the two supply approach is maximizing the efficiency. The second supply is at least V greater than output voltage and is providing the power for the control circuitry and supplies the drive current to the NPN output transistor. This allows the NPN output transistor to be driven into saturation. For the control voltage the current requirement is small equal to about % of the output current. This drive current becomes part of the output current. The maximum voltage on the Control pin is V. The maximum voltage at the Power pin is 7V. By tying the control and power inputs together the GS8 can also be operated as a single supply device. In single supply operation the dropout will be determined by the minimum control voltage. Both fixed and adjustable versions have remote sense pins, permitting very accurate regulation of output voltage. As a result, over an output current range of ma to A, the typical load regulation are less than mv. For the fixed voltages the adjust pin is brought out allowing the user to improve transient response by bypassing the internal resistor divider. Optimum transient response is provided using a capacitor in the range of.µf to µf for bypassing the Adjust pin. In addition to the enhancements mentioned, the reference accuracy has been improved by a factor of two with a guaranteed initial tolerance of ±% at ºC and.6% accuracy over the full temperature and load current range. Typical applications for the GS8 include.v to. conversion with a control supply, to.v conversion with a V control supply. The device is fully protected against over current and over temperature conditions.

6 Application Information (Continue) GROUNDING AND OUTPUT SENSEING The GS8 allows true Kelvin sensing for both the high and low side of the load. As a result the voltage regulation at the load can be easily optimized. Voltage drops due to parasitic resistances between the regulator and the load can be placed inside the regulation loop. The advantages of the remote sensing are illustrated in Figures through. Figure shows the device connected as a conventional terminal regulator with the sense lead connected directly to the output of the device. Rp is the parasitic resistance of the connections between the device and the load. Trace A of Figure illustrates the effect of Rp..V GS8 RP LOAD R R RP Figure. Conventional load sensing Figure shows the device connected to take advantage of the remote sense feature. The Sense pin and the top of the resistor divider are connected to the top of the load..v GS8 RP LOAD R R RP Figure. Remote load sensing The bottom of the resistor divider is connected to the bottom of the load. The effect on output regulation can be seen in trace B of Figure. It is important to note that the voltage drops due to Rp are not eliminated; they will add to the dropout voltage of the regulator regardless. The GS8 can control the voltage at the load as long as the input-output voltage is greater than the total of the dropout voltage of the device plus the voltage drop across Rp. VOUT Figure IOUT x RP VOUT Figure IOUT Time Figure. Remote Sensing Improves Load Regulation 6

7 Application Information (Continue) STABILITY The circuit design used in the GS8 series requires the use of an output capacitor as part of the device frequency compensation. The addition of µf aluminum electrolytic or a µf solid tantalum on the output will ensure stability for all operating conditions. OUTPUT VOLTAGE The GS8 (adjustable version) develops a. reference voltage between the Sense pin and the Adjust pin (Figure ). Placing a resistor between these two terminals causes a constant current to flow through R and down though R to set the output voltage. In general R is chosen so that this current is the specified minimum load current of ma. The current out of the Adjust pin is small, typically µa and it adds to the current from R. For the best regulation the top of the resistor divider should be connected directly to the Sense pin. VCONTROL VPOWER GS8 IADJ uf VOUT =VREF x (+ R / R ) +IADJ x R VREF VOUT R R THERMAL CONSIDERATIONS Figure. Setting Output Voltage The GS8 series have internal power and thermal limiting circuitry designed to protect the device under overload conditions. However, maximum junction temperature ratings should not be exceeded under continuous normal load conditions. Careful consideration must be given to all sources of thermal resistance from junction ambient, including junction to case, case to-heat sink interface and heat sink resistance itself. Junction temperature of the control section can run up to ºC. Junction temperature of the Power section can run up to ºC. PROTECTION DIODES In normal operation GS8 family does not need any protection diodes between the adjustment pin and the output to the input to prevent die overstresses. Internal resistors are limiting the internal current paths on the ADJ pin. Therefore even with bypass capacitors on the adjust pin no protection diode is needed to ensure device safety under short-circuit conditions. The adjust pin can be driver on a transient basis ±7V with respect to the output with out any device degradation. A protection diode between the V OUT pin and V POWER pin is not usually needed. Microsecond surge currents of A to A can be handled by the internal diode between the Output pin and V POWER pin of the device. In normal operations it is difficult to get those values of surge currents even with the use of large output capacitance. Only with high value output capacitors, such as µf to µf and the V POWER pin are instantaneously shorted to ground, damage can occur. A diode from output to input is recommended (Figure). VCONTROL VPOWER GS8 VOUT R R Figure. Optional Clamp Diodes Protect Against Input Crowbar Circuits If GS8 is connected as a single supply device with the control and power input pins shorted together the internal diode between the output and the power input pin will protect the control input pin. 7

8 Package Dimension TO-6-L PLASTIC PACKAGE Globaltech Semiconductor D A c b A e c e Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A A....6 B b c.... c D E e.7typ.67typ e L L L V.6 REF. REF 8

9 TO--L PLASTIC PACKAGE Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A A..7.. b b b b C C C D D....7 E E e.7 BSC. BSC H L L.7 REF.8 REF L.8 REF. REF L. REF. REF θ 8 8 θ 7 REF 7 REF 9

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:7// Version_.)

800mA Low Dropout Voltage Regulator

800mA Low Dropout Voltage Regulator Product Description The series of adjustable and fixed voltage regulators are designed to provide 800mA output current and to operate down to 1V input-to-output differential.