LP38692

LP38690/LP38692 1A Low Dropout CMOS Linear Regulators Stable with Ceramic Output Capacitors January 2005 LP38690/LP38692 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, VOUT = 5V), and excellent 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 µA regardless of load current, input voltage, or operating temperature. Dropout Voltage: 450 mV (typ) @ 1A (typ. 5V out). Ground Pin Current: 55 µA (typ) at full load. Precision Output Voltage: 2.5% (25˚C) accuracy. Features n n n n n n n n n n 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 1µA off-state quiescent current Thermal overload protection Foldback current limiting T0-252, SOT-223 and 6-Lead LLP packages Enable pin (LP38692) Applications n n n n Hard Disk Drives Notebook Computers Battery Powered Devices Portable Instrumentation Typical Application Circuits 20126601 20126602 Note: * Minimum value required for stability. **LLP package devices only. © 2005 National Semiconductor Corporation DS201266 www.national.com LP38690/LP38692 Connection Diagrams 20126603 TO-252, Top View LP38690DT-X.X 20126604 SOT-223, Top View LP38692MP-X.X 20126605 6-Lead LLP, Bottom View LP38690SD-X.X 20126606 6-Lead LLP, Bottom View LP38692SD-X.X Pin Description PIN VIN GND SNS DESCRIPTION This is the input supply voltage to the regulator. For LLP devices, both VIN pins must be tied together for full current operation (500mA maximum per pin). 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. 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 VOUT. The enable pin allows the part to be turned ON and OFF by pulling this pin high or low. Regulated output voltage. VEN VOUT Ordering Information Order Number LP38690SD-1.8 LP38690SD-2.5 LP38690SD-3.3 LP38690SD-5.0 LP38690DT-1.8 LP38690DT-2.5 LP38690DT-3.3 LP38690DT-5.0 LP38692SD-1.8 LP38692SD-2.5 LP38692SD-3.3 LP38692SD-5.0 LP38692MP-1.8 www.national.com Package Marking L113B L114B L115B L116B LP38690DT-1.8 LP38690DT-2.5 LP38690DT-3.3 LP38690DT-5.0 L123B L124B L125B L126B LJPB Package Type 6-Lead LLP 6-Lead LLP 6-Lead LLP 6-Lead LLP TO-252 TO-252 TO-252 TO-252 6-Lead LLP 6-Lead LLP 6-Lead LLP 6-Lead LLP SOT-223 2 Package Drawing SDE06A SDE06A SDE06A SDE06A TD03B TD03B TD03B TD03B SDE06A SDE06A SDE06A SDE06A MP05A Supplied As 1000 Units Tape and Reel 1000 Units Tape and Reel 1000 Units Tape and Reel 1000 Units Tape and Reel Available Soon Available Soon Available Soon Available Soon 1000 Units Tape and Reel 1000 Units Tape and Reel 1000 Units Tape and Reel 1000 Units Tape and Reel 1000 Units Tape and Reel LP38690/LP38692 Ordering Information Order Number LP38692MP-2.5 LP38692MP-3.3 LP38692MP-5.0 LP38690SDX-1.8 LP38690SDX-2.5 LP38690SDX-3.3 LP38690SDX-5.0 LP38690DTX-1.8 LP38690DTX-2.5 LP38690DTX-3.3 LP38690DTX-5.0 LP38692SDX-1.8 LP38692SDX-2.5 LP38692SDX-3.3 LP38692SDX-5.0 LP38692MPX-1.8 LP38692MPX-2.5 LP38692MPX-3.3 LP38692MPX-5.0 LJRB LJSB LJTB L113B L114B L115B L116B (Continued) Package Type SOT-223 SOT-223 SOT-223 6-Lead LLP 6-Lead LLP 6-Lead LLP 6-Lead LLP TO-252 TO-252 TO-252 TO-252 6-Lead LLP 6-Lead LLP 6-Lead LLP 6-Lead LLP SOT-223 SOT-223 SOT-223 SOT-223 Package Drawing MP05A MP05A MP05A SDE06A SDE06A SDE06A SDE06A TD03B TD03B TD03B TD03B SDE06A SDE06A SDE06A SDE06A MP05A MP05A MP05A MP05A Supplied As 1000 Units Tape and Reel 1000 Units Tape and Reel 1000 Units Tape and Reel 4500 Units Tape and Reel 4500 Units Tape and Reel 4500 Units Tape and Reel 4500 Units Tape and Reel Available Soon Available Soon Available Soon Available Soon 4500 Units Tape and Reel 4500 Units Tape and Reel 4500 Units Tape and Reel 4500 Units Tape and Reel 2000 Units Tape and Reel 2000 Units Tape and Reel 2000 Units Tape and Reel 2000 Units Tape and Reel Package Marking LP38690DT-1.8 LP38690DT-2.5 LP38690DT-3.3 LP38690DT-5.0 L123B L124B L125B L126B LJPB LJRB LJSB LJTB 3 www.national.com LP38690/LP38692 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Storage Temperature Range Lead Temp. (Soldering, 5 seconds) ESD Rating (Note 3) Power Dissipation (Note 2) V(max) All pins (with respect to GND) −65˚C to +150˚C 260˚C 2 kV Internally Limited -0.3V to 12V IOUT Junction Temperature Internally Limited −40˚C to +150˚C Operating Ratings VIN Supply Voltage Operating Junction Temperature Range 2.7V to 10V −40˚C to +125˚C Electrical Characteristics Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN = VOUT + 1V, CIN = COUT = 10 µF, ILOAD = 10mA. Min/Max limits are guaranteed through testing, statistical correlation, or design. Symbol Parameter Conditions MIN -2.5 VO ∆VO/∆VIN ∆VO/∆IL Output Voltage Tolerance Output Voltage Line Regulation (Note 6) Output Voltage Load Regulation (Note 7) 100 µA < IL < 1A VO + 1V ≤ VIN ≤ 10V VO + 0.5V ≤ VIN ≤ 10V IL = 25mA 1 mA < IL < 1A VIN = VO + 1V (VO = 1.8V) IL = 1A (VO = 2.5V) IL = 0.1A IL = 1A VIN - VOUT Dropout Voltage (Note 8) (VO = 3.3V) IL = 0.1A IL = 1A (VO = 5V) IL = 0.1A IL = 1A IQ IL(MIN) IFB PSRR TSD TSD (HYST) Quiescent Current Minimum Load Current Foldback Current Limit Ripple Rejection Thermal Shutdown Activation (Junction Temp) Thermal Shutdown Hysteresis (Junction Temp) VIN ≤ 10V, IL =100 µA - 1A VEN ≤ 0.4V, (LP38692 Only) VIN - VO ≤ 4V VIN - VO > 5V VIN - VO < 4V VIN = VO + 2V(DC), with 1V(p-p) / 120Hz Ripple 450 1500 55 160 ˚C 10 -5.0 0.03 1.8 950 80 800 65 650 45 450 55 0.001 TYP (Note 4) MAX 2.5 5.0 0.1 5 1600 145 1300 110 1000 100 800 100 1 100 mA dB µA mV %VOUT Units %/V %/A www.national.com 4 LP38690/LP38692 Electrical Characteristics Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN = VOUT + 1V, CIN = COUT = 10 µF, ILOAD = 10mA. Min/Max limits are guaranteed through testing, statistical correlation, or design. (Continued) Symbol en VO (LEAK) VEN Parameter Output Noise Output Leakage Current Enable Voltage (LP38692 Only) Conditions BW = 10Hz to 10kHz VO = 3.3V VO = VO(NOM) + 1V @ 10VIN Output = OFF Output = ON, VIN = 4V Output = ON, VIN = 6V Output = ON, VIN = 10V IEN Enable Pin Leakage VEN = 0V or 10V, VIN = 10V 1.8 3.0 4.0 -1 0.001 1 µA MIN TYP (Note 4) 0.7 0.5 12 0.4 V MAX Units µV/ µA 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 ( θJ-A) for the TO-252 is approximately 90˚C/W for a PC board mounting with the device soldered down to minimum copper area (less than 0.1 square inch). If one square inch of copper is used as a heat dissipator for the TO-252, the θJ-A drops to approximately 50˚C/W. The SOT-223 package has a θJ-A 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 θJ-A 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 LP38690/LP38692 Block Diagrams 20126607 FIGURE 1. LP38690 Functional Diagram (LLP) 20126608 FIGURE 2. LP38690 Functional Diagram (TO-252) www.national.com 6 LP38690/LP38692 Block Diagrams (Continued) 20126609 FIGURE 3. LP38692 Functional Diagram (LLP) 20126610 FIGURE 4. LP38692 Functional Diagram (SOT-223) 7 www.national.com LP38690/LP38692 Typical Performance Characteristics Unless otherwise specified: TJ = 25˚C, CIN = COUT = 10 µF, enable pin is tied to VIN (LP38692 only), VOUT = 1.8V, VIN = VOUT +1V, IL = 10mA. Noise vs Frequency Noise vs Frequency 20126635 20126636 Noise vs Frequency Ripple Rejection 20126637 20126618 Ripple Rejection Ripple Rejection 20126620 20126622 www.national.com 8 LP38690/LP38692 Typical Performance Characteristics Unless otherwise specified: TJ = 25˚C, CIN = COUT = 10 µF, enable pin is tied to VIN (LP38692 only), VOUT = 1.8V, VIN = VOUT +1V, IL = 10mA. (Continued) Line Transient Response Line Transient Response 20126624 20126626 Line Transient Response Load Transient Response 20126628 20126640 Load Transient Response Load Transient Response 20126641 20126642 9 www.national.com LP38690/LP38692 Typical Performance Characteristics Unless otherwise specified: TJ = 25˚C, CIN = COUT = 10 µF, enable pin is tied to VIN (LP38692 only), VOUT = 1.8V, VIN = VOUT +1V, IL = 10mA. (Continued) Load Transient Response Load Transient Response 20126643 20126644 VOUT vs Temperature (5.0V) VOUT vs Temperature (3.3V) 20126630 20126631 VOUT vs Temperature (2.5V) VOUT vs Temperature (1.8V) 20126632 20126633 www.national.com 10 LP38690/LP38692 Typical Performance Characteristics Unless otherwise specified: TJ = 25˚C, CIN = COUT = 10 µF, enable pin is tied to VIN (LP38692 only), VOUT = 1.8V, VIN = VOUT +1V, IL = 10mA. (Continued) Dropout Voltage vs IOUT Dropout Voltage vs IOUT 20126650 20126651 Enable Voltage vs Temperature Load Regulation vs Temperature 20126652 20126653 Line Regulation vs Temperature 20126654 11 www.national.com LP38690/LP38692 Application Hints EXTERNAL CAPACITORS Like any low-dropout regulator, external capacitors are required to assure stability. These capacitors must be correctly selected for proper performance. INPUT CAPACITOR: An input capacitor of at least 1µF is required (ceramic recommended). The capacitor must be located not more than one centimeter from the input pin 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 1µF. 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 Characteristics section). This pin should be tied to VIN 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 VOUT. Typically, when this differential voltage exceeds 5V, the load current will limit at about 450 mA. When the VIN - VOUT differential is reduced below 4V, load current is limited to about 1500 mA. SELECTING A CAPACITOR It is important to note that capacitance tolerance and variation 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 temperature range. Capacitor Characteristics CERAMIC: For values of capacitance in the 10 to 100 µF 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 mΩ). 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 nominal capacitance at high and low limits of the temperature range. X7R and X5R dielectric ceramic capacitors are strongly recommended if ceramics are used, as they typically maintain a capacitance range within ± 20% of nominal over full operating ratings of temperature and voltage. Of course, they are typically larger and more costly than Z5U/Y5U types for a given voltage and capacitance. TANTALUM: Solid Tantalum capacitors have good temperature stability: a high quality Tantalum will typically show a capacitance value that varies 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 COUT near the device with short traces to the VIN, VOUT, and ground pins. The regulator ground pin should be connected to the external 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 VOUT, 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 any integrated circuit’s performance because of the small dimensions of the geometries inside the device. In applications where circuit sources are present which generate signals with significant high frequency energy content ( > 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 capacitors 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 RF isolation from the load. It is recommended that some inductance be placed between the output capacitor and the load, and good RF bypass capacitors 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 possible, and grounded through a separate path. At MHz frequencies, 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. www.national.com 12 LP38690/LP38692 Application Hints OUTPUT NOISE (Continued) Attention should be paid to the units of measurement. Spot noise is measured in units µV/root-Hz or nV/root-Hz and total output noise is measured in µV(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 increases the total supply current (ground pin current). 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 www.national.com LP38690/LP38692 Physical Dimensions inches (millimeters) unless otherwise noted 6-lead, LLP Package NS Package Number SDE06A TO-252 Package NS Package Number TD03B www.national.com 14 LP38690/LP38692 1A Low Dropout CMOS Linear Regulators Stable with Ceramic Output Capacitors Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 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 and 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. 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