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ISSUED DATE :2003/06/14 REVISED DATE :2006/03/29E
GU1084
5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
The GU1084 is a low dropout positive adjustable or fixed mode regulator with minimum of 5.0A output current capability .The product is specifically designed to provide well regulated supply for low voltage IC applications such as high speed bus termination and low current 3.3v logic supply. GU1084 is also well suited for other applications such as VGA cards. GU1084 is guaranteed to have lower than 1.5V dropout at full load current making it ideal to provide well regulated outputs of 1.25 to 3.3V with 4.7 to 12V input supply.
Description
Features & maximum dropout at full load current 1.5V
Package Dimensions
&Built-in thermal shutdown &Output current limiting &Adjustable output voltage or fixed 1.5V,1.8V,2.5V,3.3V,5.0V &Fast transient response &Good noise rejection
REF.
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A b L4 c L3 L1 E
Millimeter REF. Min. Max. 4.40 4.80 c2 0.76 1.00 b2 0.00 0.30 B D 0.36 0.5 e 1.50 REF. L 2.29 2.79 9.80 10.4 L2
Millimeter Min. Max. 1.25 1.45 1.17 1.47 8.6 9.0 2.54 REF. 14.6 15.8 0 8 1.27 REF.
Typical Circuit
Block Diagram
Pin Descriptions
Name Adj (GND) Vout O I/O PIN# 1 2 Adjustable (Ground only for fixed mode) The output of the regulator. A minimum of 10uF capacitor must be connected from this pin to ground to insure stability. The input pin of regulator .Typically a large storage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimum dropout voltage during the load transient response .This pin must always be 1.5V higher than Vout in order for the device to regulate properly. FUNCTION
Vin
I
3
GU1084
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ISSUED DATE :2003/06/14 REVISED DATE :2006/03/29E
Absolute Maximum Ratings
Symbol Vin PD TST TOP DC Supply Voltage Power Dissipation Storage Temperature Operating Junction Temperature Range Parameter Ratings -0.3 to 12 Internally Limited -65 ~ + 150 0 ~ + 150 : : Unit V
Electrical Characteristics
Symbol VREF Parameter GU1084ADJ GU1084-1.5 GU1084-1.8 Output Voltage GU1084-2.5 GU1084-3.3 GU1084-5.0 Line Regulation GU1084XXX GU1084ADJ GU1084-1.5 Load Regulation GU1084-1.8 GU1084-2.5 GU1084-3.3 GU1084-5.0 Vo ILIM IMIN IADJ IQ Dropout Voltage Current Limit Minimum Load Current Adjust Pin Current Quiescent Current Temperature Stability JA JC Thermal Resistance Junction-to-Ambient(No heat sink ;No air flow) Thermal Resistance Junction-to-Case Conditions(Notes) Io=10mA, Tj=25 : , (Vin-Vout )=1.5V Io=10mA, Tj=25 : , 3.0V Vin 12V Io=10mA, Tj=25 : , 3.3V Vin 12V Io=10mA, Tj=25 : , 4.0V Vin 12V Io=10mA, Tj=25 : , 4.8V Vin 12V Io=10mA, Tj=25 : , 6.5V Vin 12V Io=10mA, Vout+1.5VNote 1: See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured at a constant junction Temperature by low duty cycle pulse testing .Load regulation is measured at the output lead =1/18" from the package. Note 2: Line and load regulation are guaranteed up to the maximum power dissipation of 15W. Power dissipation is determined by the difference between input and output and the output current .Guaranteed maximum power dissipation will not be available over the full input/output range.
GU1084
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ISSUED DATE :2003/06/14 REVISED DATE :2006/03/29E
Functional Description
Introduction The GU1084 adjustable Low Dropout (LDO) regulator is a 3 terminal device that can easily be programmed with the addition of two external resistors to any voltages within the range of 1.25V to 2.5V. The GU1084 only needs 1.5V differential between Vin and Vout to maintain output regulation, the output voltage tolerances are also extremely tight and they include the transient response as port of the specification. For example, Intel VRE specification calls for a total of +/-100mV including initial tolerance, load regulation and 0 to 5.0A load step. The GU1084 is specifically designed to meet the fast current transient needs as well as providing an accurate initial voltage, reducing the overall system cost with the need for fewer output capacitors. Output Voltage Setting The GU1084 can be programmed to any voltages in the range of 1.25V to 5V with the addition of R1 and R2 external resistors According to the following formula:
The GU1084 keeps a constant 1.25V between the output pin and the adjust pin. By placing a resistor R1 across these two pins a constant current flows through R1, adding to the Iadj current requirement of the GU1084 is 10mA, R1 is typically selected to be 121 resistor so that It automatically satisfies the minimum current requirement .Notice that since Iadj is typically in the range of 55uA it only adds a small error to the output voltage and should only be considered when a very precise output voltage setting is required. For example, in a typical 3.3V application where R1=121 and R2=200 the error due to Iadj is only 0.3% of the nominal set point. Load Regulation Since the GU1084 is only a 3 terminal device, it is not possible to provide true remote sensing of the output voltage at the load. The best load Regulation is achieved when the bottom side of R2 is connected to the load and the top-side of R1 resistor is connected directly to the case or the Vout pin of the regulator and not to the load. It is important to note that for high current applications, this can re-present a significant percentage of the overall load regulation and one must keep the path from the regulator to the load as short as possible to minimize this effect. Stability The GU1084 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable .For most applications a minimum of 10uF aluminum electrolytic capacitor insures both stability and good transient response. Thermal Design The GU1084 incorporates an internal shutdown that protects the device when the junction temperature exceeds the maximum allowable junction temperatures. Although this device can operate with junction temperatures in the range of 150 : , it is recommended that the selected heat sink be chosen such that during maximum continuous load operation the junction temperature is kept below the temperature. Layout Consideration The output capacitors must be located as close to the Vout terminal of the device as possible .It is recommended to use a section of a layer of the PC board as a plane to connect the Vout pin to the output capacitors to prevent any high frequency oscillation that may result due to excessive trace inductance.
GU1084
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ISSUED DATE :2003/06/14 REVISED DATE :2006/03/29E
Performance Characteristics
Important Notice: All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM. GTM reserves the right to make changes to its products without notice. GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems. GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance. Head Office And Factory: Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C. TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785 China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165
GU1084
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