National LP38690/LP38692 handbook
Contents
1. 2 AN x E 5 gt m 00 ViN AC 1V p p OUT 3 3V 10 100 1k 100k FREQUENCY Hz FREQUENCY Hz 20126637 20126618 Ripple Rejection Ripple Rejection ics CN m NL 5 il z M 4 gt 5 X N ul u Y 9 IN Y Vin AC 1V p p OUT 3 3V 10 100 1k 100k 10 100 1k 100k FREQUENCY Hz FREQUENCY Hz 20126620 20126622 www national com 8 Typical Performance Characteristics uniess otherwise specified T 25 Cn Cour 10 pF Line Transient Response Line Transient Response AVour mV AVour mV gt lt gt 200 us DIV 100 us DIV 20126624 Line Transient Response Load Transient Response gt E es N p Vour E 2 m 309 5 lt gt 2 gt 100 us DIV 200 us DIV 20126628 Load Transient Response Load Transient Response 20126626 20126640 40 us DIV 40 us DIV 20126641 20126642 www national com 6698 d 1 0698Ed 1 LP38690 LP38692 Typical Performance Characteristics uniess otherwise specified T 25 Cn Cour 10 pF enable pin is tied to Vi LP38692 only 1 8V Vin Vout 1V 10mA Continued Load Transient Response Load Transient Response AVour mV 10 us DIV 10 us DIV 20126643 20126644 Vour VS Temperature 5 0V Vour VS Temperature 3 3V z2. 1202 Ripple mA Tsp Thermal Shutdown Activation Tsp HYST Thermal Shutdown Hysteresis Junction Temp www national com 4 Electrical Characteristics Limits in standard typeface are for T 25 and limits in boldface type apply over the full operating temperature range Unless otherwise specified Vin Vour 1V Cin Court 10 pF 10mA Min Max limits are guaranteed through testing statistical correlation or design Continued TYP Symbol Parameter Conditions MAX Units Note 4 e Output Noise BW 10Hz to 10kHz T Vo LEAK Output Leakage Curent Vo VONOM ive ow 65 9 m 38 30 Note 1 Absolute maximum ratings indicate limits beyond which damage to the component may occur Operating ratings indicate conditions for which the device is intended to be functional but do not guarantee specific performance limits For guaranteed specifications see Electrical Characteristics Specifications do not apply when operating the device outside of its rated operating conditions Note 2 At elevated temperatures device power dissipation must be derated based on package thermal resistance and heatsink values if a heatsink is used The junction to ambient thermal resistance 65 4 for the TO 252 is approximately 90 C W for a PC board mounting with the device soldered down to minimum c
3. Vout LP38690 SNS 20126601 Vour Vout LP38692 Note Minimum value required for stability LLP package devices only 2005 National Semiconductor Corporation DS201266 1 uF 20126602 www national com 5707 ndino 2 e qe g 542319 69 1694 7 SOIND 1nodougq VI Z698Ed 1 0698Ed 1 LP38690 LP38692 Connection Diagrams GND VIN Tab is GND VoUT 20126603 TO 252 Top View LP38690DT X X Ven 20126604 SOT 223 Top View LP38692MP X X 20126605 20126606 6 Lead LLP Bottom View 6 Lead LLP Bottom View LP38690SD X X LP38692SD X X Pin Description DESCRIPTION MEE This is the input supply voltage to the regulator For LLP devices both Vi pins must be tied G ViN together for full current operation 500 maximum per pin ND Circuit ground for the regulator This is connected to the die through the lead frame and also functions as the heat sink when the large ground pad is soldered down to a copper plane S VEN NS Output sense pin allows remote sensing at the load which will eliminate the error in output voltage due to voltage drops caused by the resistance in the traces between the regulator and the load This pin must be tied to OO Vw The enable pin allows the part to be turned ON and OFF by pulling this pin high or low Regulated output voltage Ordering Information www national com 2 Ordering Infor
4. sible and grounded through a separate path At MHz fre quencies ground planes begin to look inductive and RFI EMI can cause ground bounce across the ground plane In multi layer PCB applications care should be taken in layout so that noisy power and ground planes do not radiate directly into adjacent layers which carry analog power and ground Application Hints continued OUTPUT NOISE Noise is specified in two ways Spot Noise or Output Noise Density is the RMS sum of all noise sources measured at the regulator output at a specific frequency measured with a 1Hz bandwidth This type of noise is usually plotted on a curve as a function of frequency Total Output Noise or Broad Band Noise is the RMS sum of spot noise over a specified bandwidth usually several decades of frequencies 13 Attention should be paid to the units of measurement Spot noise is measured in units LI V root Hz or nV root Hz and total output noise is measured in p V rms The primary source of noise in low dropout regulators is the internal reference Noise can be reduced in two ways by increasing the transistor area or by increasing the current drawn by the internal reference Increasing the area will decrease the chance of fitting the die into a smaller package Increasing the current drawn by the internal reference in creases the total supply current ground pin current www national com 6698 d 1 0698Ed 1 LP38690 LP38692 Physical DIMEN
5. capacitance tolerance and varia tion with temperature must be taken into consideration when selecting a capacitor so that the minimum required amount of capacitance is provided over the full operating tempera ture range Capacitor Characteristics CERAMIC For values of capacitance in the 10 to 100 range ceramics are usually larger and more costly than tantalums but give superior AC performance for bypassing high frequency noise because of very low ESR typically less than 10 mQ However some dielectric types do not have good capacitance characteristics as a function of voltage and temperature Z5U and Y5V dielectric ceramics have capacitance that drops severely with applied voltage A typical Z5U or Y5V capacitor can lose 60 of its rated capacitance with half of the rated voltage applied to it The Z5U and Y5V also exhibit a severe temperature effect losing more than 50 of nomi nal capacitance at high and low limits of the temperature range X7R and 58 dielectric ceramic capacitors are strongly rec ommended if ceramics are used as they typically maintain a capacitance range within 20 of nominal over full operat ing ratings of temperature and voltage Of course they are typically larger and more costly than Z5U Y5U types for a given voltage and capacitance www national com TANTALUM Solid Tantalum capacitors have good tempera ture stability a high quality Tantalum will typically show a Capacitance value that vari
6. 698Ed 1 LP38690 LP38692 Block Diagrams IN N C O GND GND C www national com MOSFET gt DRIVER P FET ENABLE LOGIC THERMAL 1 mm SHUTDOWN FOLDBACK CURRENT O Vour LIMITING SSNS R1 20126607 FIGURE 1 LP38690 Functional Diagram LLP MOSFET gt FOLDBACK CURRENT OV LIMITING THERMAL w m 25 SHUTDOWN w m OUT 20126608 FIGURE 2 LP38690 Functional Diagram TO 252 Block Diagrams continued Vin MOSFET DRIVER LOGIC FOLDBACK Qv CURRENT OUT LIMITING O SNS THERMAL 1 25 SHUTDOWN REFERENCE GND C 20126609 FIGURE 3 LP38692 Functional Diagram LLP MOSFET DRIVER CET FOLDBACK CURRENT LIMITING V C ENABLE gt EN LOGIC THERMAL 27 SHUTDOWN REFERENCE OVouT GND Q 20126610 FIGURE 4 LP38692 Functional Diagram SOT 223 www national com 69 85 41 0698541 LP38690 LP38692 Typical Performance Characteristics Unless otherwise specified T 25 Cin Cour 10 pF enable pin is tied to Vi LP38692 only 1 8V Vin Vout 41V 10mA Noise vs Frequency Noise vs Frequency Coy 1 HF Cour 10 pF TT TITI UNL 111 m Oe on AA I z NN z gt 3 m V IN 10 100 1k 10k 100k FREQUENCY Hz FREQUENCY Hz 20126635 Noise vs Frequency Ripple Rejection MEM our 100
7. National Semiconductor National Semiconductor Americas Customer Europe Customer Support Center Support Center Fax 49 0 180 530 85 86 Email new feedback nsc com Email europe support 9 nsc com Tel 1 800 272 9959 Deutsch Tel 49 0 69 9508 6208 English Tel 44 870 24 0 2171 Frangais Tel 33 0 1 41 91 8790 National Semiconductor National Semiconductor Asia Pacific Customer Support Center Email ap support 9 nsc com Fax 81 3 5639 7507 Email jpn feedback 9 nsc com Tel 81 3 5639 7560 Japan Customer Support Center
8. O O LP38690 O National Semiconductor LP38690 LP38692 January 2005 1A Low Dropout CMOS Linear Regulators Stable with Ceramic Output Capacitors General Description The LP38690 2 low dropout CMOS linear regulators provide tight output tolerance 2 5 typical extremely low dropout voltage 450mV 1A load current 5V and excel lent AC performance utilizing ultra low ESR ceramic output capacitors The low thermal resistance of the LLP SOT 223 and T0 252 packages allow the full operating current to be used even in high ambient temperature environments The use of a PMOS power transistor means that no DC base drive current is required to bias it allowing ground pin current to remain below 100 UA regardless of load current input voltage or operating temperature Dropout Voltage 450 mV typ 1A typ 5V out Ground Pin Current 55 pA typ at full load Precision Output Voltage 2 5 25 accuracy Typical Application Circuits Features 2 5 output accuracy 25 C Low dropout voltage 450mV 1A typ 5V out Wide input voltage range 2 7V to 10V Precision trimmed bandgap reference Guaranteed specs for 40 C to 125 C 1114 off state quiescent current Thermal overload protection Foldback current limiting T0 252 SOT 223 and 6 Lead LLP packages Enable pin LP38692 Applications Hard Disk Drives Notebook Computers Battery Powered Devices Portable Instrumentation
9. SIONS inches millimeters unless otherwise noted 2 1 DIMENSIONS ARE IN MILLIMETERS DIMENSION IN FOR REFERENCE ONLY 6X L 0742 l t4X 0 95 RECOMMENDED LAND PATTERN PIN 1 INDEX AREA 0 8 MAX PIN 1 ID 45 X 0 25 6X 0 40 1 4 6x 0 352005 4 45 o 1 c bO 4x 0 95 2x 1 9 SDEO6A Rev 6 lead LLP Package NS Package Number SDEO6A Ba 11 1 1 7 1 e 2 2 285 2 1 3 1 1 4 57 be LAND PATTERN RECOMMENDATION DIMENSIONS ARE IN MILLIMETERS 6 5820 14 2 3 0 08 8 SEATING PLANE T 47 o 0 83 0 1 5 ms 3X o 1520 1 ih Los MIN 12285 Tr 2091 0 52 0 05 150 1 0038 Rev C TO 252 Package NS Package Number TD03B www national com 14 51 81 Dimensions inches millimeters unless otherwise noted Continued 3 020 1 SYMM m 3 3 1 5 6 3 0 33 6 96 0 55 SYMM SEES k a s LAND PATTERN RECOMMENDATION R0 15 0 05 TYP R0 15 0 05 TYP 0 03 1 55 1 80 1 6 GAGE PLANE 0 025 0 100 0 05 TYP 0 74 0 08 TYP 0 9 MIN TYP SEATING PLANE DIMENSIONS ARE IN MILLIMETERS MPOSA Rev A SOT 223 Package NS Package Number MP05A National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied an
10. and returned to a clean analog ground OUTPUT CAPACITOR An output capacitor is required for loop stability It must be located less than 1 centimeter from the device and connected directly to the output and ground pins using traces which have no other currents flowing through them The minimum amount of output capacitance that can be used for stable operation is 1uF Ceramic capacitors are recommended the LP38690 2 was designed for use with ultra low ESR capacitors The LP38690 2 is stable with any output capacitor ESR between zero and 100 Ohms ENABLE PIN LP38692 only The LP38692 has an enable pin which turns the regulator output on and off Pulling the enable pin down to a logic low will turn the part off The voltage the pin has to be pulled up to in order to assure the part is on depends on input voltage refer to Electrical Char acteristics section This pin should be tied to Vj if the enable function is not used Foldback Current Limiting Foldback current limiting is built into the LP38690 2 which reduces the amount of output current the part can deliver as the output voltage is reduced The amount of load current is dependent on the differential voltage between Vin and Typically when this differen tial voltage exceeds 5V the load current will limit at about 450 mA When the Vin differential is reduced below 4V load current is limited to about 1500 mA SELECTING A CAPACITOR It is important to note that
11. any integrated circuits perfor mance because of the small dimensions of the geometries inside the device In applications where circuit sources are present which generate signals with significant high fre quency energy content gt 1 MHz care must be taken to ensure that this does not affect the IC regulator If RFI EMI noise is present on the input side of the regulator such as applications where the input source comes from the output of a switching regulator good ceramic bypass ca pacitors must be used at the input pin of the IC If a load is connected to the IC output which switches at high speed such as a clock the high frequency current pulses required by the load must be supplied by the capacitors on the IC output Since the bandwidth of the regulator loop is less than 100 kHz the control circuitry cannot respond to load changes above that frequency This means the effective output impedance of the IC at frequencies above 100 kHz is determined only by the output capacitor s In applications where the load is switching at high speed the output of the IC may need HF isolation from the load It is recommended that some inductance be placed between the output capacitor and the load and good HF bypass capaci tors be placed directly across the load PCB layout is also critical in high noise environments since RFI EMI is easily radiated directly into PC traces Noisy circuitry should be isolated from clean circuits where pos
12. d National reserves the right at any time without notice to change said circuitry and specifications For the most current product information visit us at www national com LIFE SUPPORT POLICY NATIONAL S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION As used herein ssoyigedey ndino 2 e qe g sJojejnDou 1694 7 SOIND 1nodouq VI Z698Ed 1 0698Ed 1 Life support devices or systems are devices or systems which a are intended for surgical implant into the body or b support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user BANNED SUBSTANCE COMPLIANCE 2 A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification CSP 9 111C2 and the Banned Substances and Materials of Interest Specification CSP 9 111S2 and contain no Banned Substances as defined in CSP 9 111S2 www national com
13. es less than 10 15 across the full temperature range of 40 C to 125 C ESR will vary only about 2X going from the high to low temperature limits PCB LAYOUT Good PC layout practices must be used or instability can be induced because of ground loops and voltage drops The input and output capacitors must be directly connected to the input output and ground pins of the regulator using traces which do not have other currents flowing in them Kelvin connect The best way to do this is to lay out CiN and Cour near the device with short traces to the Vin and ground pins The regulator ground pin should be connected to the exter nal circuit ground so that the regulator and its capacitors have a single point ground It should be noted that stability problems have been seen in applications where vias to an internal ground plane were used at the ground points of the IC and the input and output capacitors This was caused by varying ground potentials at these nodes resulting from current flowing through the ground plane Using a single point ground technique for the regulator and it s capacitors fixed the problem Since high current flows through the traces going into Vin and coming from Kelvin connect the capacitor leads to these pins so there is no voltage drop in series with the input and output capacitors RFI EMI SUSCEPTIBILITY RFI radio frequency interference and EMI electromagnetic interference can degrade
14. mation continued 3 www national com 6698 d 1 0698Ed 1 LP38690 LP38692 Absolute Maximum Ratings Note 1 oos Internally Limited If Military Aerospace specified devices are required Junction Temperature 40 to 150 C please contact the National Semiconductor Sales Office Distributors for availability and specifications Operating Ratings Storage Temperature Range 65 C to 150 C 260 C Vin Supply Voltage 2 7V to 10V 40 C to 125 Lead Temp Soldering 5 seconds ESD Rating Note 3 2 kV Operating Junction Power Dissipation Note 2 Internally Limited temperature Pange V max All pins with respect to GND 0 3V to 12V Electrical Characteristics Limits in standard typeface are for T 25 C and limits in boldface type apply over the full operating temperature range Unless otherwise specified Vin Vour 1V Cin 10 pF 10 Min Max limits are guaranteed through testing statistical correlation or design TYP Symbol Parameter Conditions MAX Units Note 4 es J 2 Output Voltage Tolerance 100 1A fo Vour Vo 1V Vi lt 10V Note 6 25 Note 7 Vin Vo 1V Vin Vout Dropout Voltage Note 8 3 65 110 mV 650 1000 la Quiescent Current Vin 10V 100 pA 1A 55 10 Ven lt 0 4V LP38692 Only 0 001 pA MIN Minimum Load Current Vis ies Foldback Current Limit Vin Vo gt 5V
15. opper area less than 0 1 square inch If one square inch of copper is used as a heat dissipator for the TO 252 the 0 4 drops to approximately 50 C W The SOT 223 package has a 0 of approximately 125 C W when soldered down to a minimum sized pattern less than 0 1 square inch and approximately 70 C W when soldered to a copper area of one square inch The values for the LLP package are also dependent on trace area copper thickness and the number of thermal vias used refer to application note AN 1187 If power disspation causes the junction temperature to exceed specified limits the device will go into thermal shutdown Note 3 ESD is tested using the human body model which is a 100pF capacitor discharged through a 1 5k resistor into each pin Note 4 Typical numbers represent the most likely parametric norm for 25 C operation Note 5 If used in a dual supply system where the regulator load is returned to a negative supply the output pin must be diode clamped to ground Note 6 Output voltage line regulation is defined as the change in output voltage from nominal value resulting from a change in input voltage Note 7 Output voltage load regulation is defined as the change in output voltage from nominal value as the load current increases from 1mA to full load Note 8 Dropout voltage is defined as the minimum input to output differential required to maintain the output within 100mV of nominal value 5 www national com 6698 d 1 0
16. z lt lt gt gt LLI LLI as as 50 25 0 25 50 75 100 125 TEMPERATURE C TEMPERATURE C 20126630 20126631 Vout VS Temperature 2 5V Vout VS Temperature 1 8V z gt lt lt lt gt LLI a 5 50 25 0 25 50 75 100 125 50 25 0 25 50 75 100 125 TEMPERATURE C TEMPERATURE C 20126632 20126633 www national com 10 Typical Performance Characteristics uniess otherwise specified 25 Cn Cour 10 pF enable pin is tied to Vi LP38692 only 1 8V Vin Vout 1V 10mA Continued Dropout Voltage vs lour Dropout Voltage vs lout I V Vpropout MV 20126650 20126651 Enable Voltage vs Temperature Load Regulation vs Temperature 1 0 1 5 lt n 20 gt 5 Z gt lt E 2 5 gt lt 3 0 3 5 50 TEMPERATURE C TEMPERATURE C 20126652 20126653 Line Regulation vs Temperature 0 034 AVourTlAV N 50 25 0 25 50 75 100 125 TEMPERATURE C 20126654 11 www national com 6698 d 1 0698Ed 1 LP38690 LP38692 Application Hints EXTERNAL CAPACITORS Like any low dropout regulator external capacitors are re quired to assure stability These capacitors must be correctly selected for proper performance INPUT CAPACITOR An input capacitor of at least 1pF is required ceramic recommended The capacitor must be located not more than one centimeter from the input pin
Download Pdf Manuals
Related Search
National LP38690/LP38692 handbook