MIC2571 Micrel MIC2571 Single-Cell Switching Regulator Final Information General Description Features Micrel's MIC2571 is a micropower boost switching regulator that operates from one alkaline, nickel-metal-hydride cell, or lithium cell. The MIC2571 accepts a positive input voltage between 0.9V and 15V. Its typical no-load supply current is 120A. * Operates from a single-cell supply 0.9V to 15V operation * 120A typical quiescent current * Complete regulator fits 0.3 in2 area * 2.85V/3.3V/5V selectable output voltage (MIC2571-1) * Adjustable output up to 36V (MIC2571-2) * 1A current limited pass element * Frequency synchronization input * 8-lead MSOP package The MIC2571 is available in selectable fixed output or adjustable output versions. The MIC2571-1 can be configured for 2.85V, 3.3V, or 5V by connecting one of three separate feedback pins to the output. The MIC2571-2 can be configured for an output voltage ranging between its input voltage and 36V, using an external resistor network. The MIC2571 has a fixed switching frequency of 20kHz. An external SYNC connection allows the switching frequency to be synchronized to an external signal. The MIC2571 requires only four components (diode, inductor, input capacitor and output capacitor) to implement a boost regulator. A complete regulator can be constructed in a 0.3 in2 area. Applications * * * * * * * Pagers LCD bias generator Battery-powered, hand-held instruments Palmtop computers Remote controls Detectors Battery Backup Supplies All versions are available in an 8-lead MSOP with an operating range from -40C to +85. Typical Applications D1 MBR0530 L1 150H D1 MBR0530 L1 150H 5V/5mA 3.3V/8mA 8 8 IN 1V to1.5V 1 Cell C1* 47F 16V MIC2571-1 SW 1 2.85V 6 3.3V 5 5V SYNC 7 4 GND 2 IN 1V to1.5V 1 Cell C1* 47F 16V MIC2571-1 SW 1 2.85V 6 3.3V 5 5V C2 47F 16V SYNC 7 * Needed if battery is 4" from MIC2571 Circuit size < 0.3 in2 excluding C1 4 GND 2 C2 47F 16V * Needed if battery is 4" from MIC2571 Circuit size < 0.3 in2 excluding C1 Single-Cell to 5V DC-to-DC Converter Single-Cell to 3.3V DC-to-DC Converter Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com 1997 1 MIC2571 MIC2571 Micrel Ordering Information Part Number Temperature Range Voltage Frequency Package MIC2571-1BMM -40C to +85C Selectable* 20kHz 8-lead MSOP MIC2571-2BMM -40C to +85C Adjustable 20kHz 8-lead MSOP * Externally selectable for 2.85V, 3.3V, or 5V Pin Configuration MIC2571-1 MIC2571-2 SW 1 8 IN SYNC GND 2 7 SYNC 6 2.85V NC 3 6 FB 5 3.3V NC 4 5 NC SW 1 8 IN GND 2 7 NC 3 5V 4 Adjustable Voltage 20kHz Frequency Selectable Voltage 20kHz Frequency 8-Lead MSOP (MM) Pin Description Pin No. (Version) Pin Name 1 SW 2 GND 3 NC Not internally connected. 4 (-1) 5V 5V Feedback (Input): Fixed 5V feedback to internal resistive divider. 4 (-2) NC Not internally connected. 5 (-1) 3.3V 5 (-2) NC 6 (-1) 2.85V 6 (-2) FB Feedback (Input): 0.22V feedback from external voltage divider network. 7 SYNC Synchronization (Input): Oscillator start timing. Oscillator synchronizes to falling edge of sync signal. 8 IN Pin Function Switch: NPN output switch transistor collector. Power Ground: NPN output switch transistor emitter. 3.3V Feedback (Input): Fixed 3.3V feedback to internal resistive divider. Not internally connected. 2.85V Feedback (Input): Fixed 2.85V feedback to internal resistive divider. Supply (Input): Positive supply voltage input. Example: (-1) indicates the pin description is applicable to the MIC2571-1 only. MIC2571 2 1997 MIC2571 Micrel Absolute Maximum Ratings Operating Ratings Supply Voltage (VIN) ..................................................... 18V Switch Voltage (VSW) .................................................... 36V Switch Current (ISW) ....................................................... 1A Sync Voltage (VSYNC) .................................... -0.3V to 15V Storage Temperature (TA) ....................... -65C to +150C MSOP Power Dissipation (PD) ................................ 250mW Supply Voltage (VIN) .................................... +0.9V to +15V Ambient Operating Temperature (TA) ........ -40C to +85C Junction Temperature (TJ) ....................... -40C to +125C MSOP Thermal Resistance (JA) .......................... 240C/W Electrical Characteristics VIN = 1.5V; TA = 25C, bold indicates -40C TA 85C; unless noted Parameter Condition Min Typ Input Voltage Startup guaranteed, ISW = 100mA Quiescent Current Output switch off Fixed Feedback Voltage MIC2571-1; V2.85V pin = VOUT, ISW = 100mA MIC2571-1; V3.3V pin = VOUT, ISW = 100mA MIC2571-1; V5V pin = VOUT, ISW = 100mA 2.7 3.14 4.75 2.85 3.30 5.00 3.0 3.47 5.25 V V V Reference Voltage MIC2571-2, [adj. voltage versions], ISW = 100mA, Note 1 208 220 232 mV Comparator Hysteresis MIC2571-2, [adj. voltage versions] Output Hysteresis 0.9 Max Units 15 V V A 120 6 mV MIC2571-1; V2.85V pin = VOUT, ISW = 100mA MIC2571-1; V3.3V pin = VOUT, ISW = 100mA MIC2571-1; V5V pin = VOUT, ISW = 100mA 65 75 120 mV mV mV Feedback Current MIC2571-1; V2.85V pin = VOUT MIC2571-1; V3.3V pin = VOUT MIC2571-1; V5V pin = VOUT MIC2571-2, [adj. voltage versions]; VFB = 0V 4.5 4.5 4.5 25 A A A nA Reference Line Regulation 1.0V VIN 12V 0.35 %/V Switch Saturation Voltage VIN = 1.0V, ISW = 200mA VIN = 1.2V, ISW = 600mA VIN = 1.5V, ISW = 800mA 200 400 500 mV mV mV Switch Leakage Current Output switch off, VSW = 36V 1 A Oscillator Frequency MIC2571-1, -2; ISW = 100mA 20 kHz Maximum Output Voltage 36 V Sync Threshold Voltage 0.7 V Switch On Time 35 s Currrent Limit 1.1 A 67 % Duty Cycle VFB < VREF, ISW = 100mA General Note: Devices are ESD protected; however, handling precautions are recommended. Note 1: 1997 Measured using comparator trip point. 3 MIC2571 MIC2571 Micrel Typical Characteristics Switch Saturation Voltage Switch Saturation Voltage 1.0 SWITCH CURRENT (A) SWITCH CURRENT (A) 0.8 1.4V 0.6 1.3V 0.4 1.2V 1.1V 0.2 Switch Saturation Voltage 1.0 1.4V TA = -40C 0.8 1.2V TA = 25C 0.6 1.1V 0.4 1.0V 0.2 VIN = 0.9V 1.3V 1.4V 1.3V SWITCH CURRENT (A) 1.0 1.2V TA = 85C 0.8 1.1V 0.6 1.0V 0.4 VIN = 0.9V 0.2 VIN = 1.0V 0 0.2 0.4 0.6 0.8 SWITCH VOLTAGE (V) 0 1.0 Oscillator Frequency vs. Temperature 0 1.0 0 25 20 70 0.2 0.4 0.6 0.8 SWITCH VOLTAGE (V) 1.0 Quiescent Current vs. Temperature 75 VIN = 1.5V ISW = 100mA DUTY CYCLE (%) 200 VIN = 1.5V ISW = 100mA 65 60 55 VIN = 1.5V 175 150 125 100 75 15 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) 50 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) 50 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) Feedback Current vs. Temperature Feedback Current vs. Temperature Quiescent Current vs. Supply Voltage VIN = 1.5V MIC2571-1 6 4 2 Output Current Limit vs. Temperature 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) MIC2571 VIN = 2.5V MIC2571-2 30 20 10 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) SWITCH LEAKAGE CURRENT (nA) 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) 40 200 QUIESCENT CURRENT (A) 8 50 FEEDBACK CURRENT (nA) FEEDBACK CURRENT (A) 10 -40C 175 +25C 150 125 +85C 100 75 50 25 0 Switch Leakage Current vs. Temperature 0 2 4 6 8 SUPPLY VOLTAGE (V) 10 Output Hysteresis vs. Temperature 1000 150 OUTPUT HYSTERESIS (mV) OSC. FREQUENCY (kHz) 0.2 0.4 0.6 0.8 SWITCH VOLTAGE (V) Oscillator Duty Cycle vs. Temperature 30 CURRENT LIMIT (A) 0 QUIESCENT CURRENT (A) 0 100 10 1 0.1 0.01 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) 4 125 5V 100 3.3V 75 50 VOUT = 2.85V 25 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) 1997 MIC2571 Micrel Block Diagrams VBATT VOUT IN SYNC MIC2571-1 Oscillator 0.22V Reference 5V 3.3V Driver SW 2.85V GND Selectable Voltage Version with External Components VBATT VOUT IN SYNC MIC2571-2 Oscillator 0.22V Reference Driver FB SW GND Adjustable Voltage Version with External Components 1997 5 MIC2571 MIC2571 Micrel Supply Voltage 5V IPEAK Output Voltage The MIC2571 switch-mode power supply (SMPS) is a gated oscillator architecture designed to operate from an input voltage as low as 0.9V and provide a high-efficiency fixed or adjustable regulated output voltage. One advantage of this architecture is that the output switch is disabled whenever the output voltage is above the feedback comparator threshold thereby greatly reducing quiescent current and improving efficiency, especially at low output currents. Refer to the Block Diagrams for the following discription of typical gated oscillator boost regulator function. Peak Current Functional Description VIN 0V 0mA 5V Time The bandgap reference provides a constant 0.22V over a wide range of input voltage and junction temperature. The comparator senses the output voltage through an internal or external resistor divider and compares it to the bandgap reference voltage. When the voltage at the inverting input of the comparator is below 0.22V, the comparator output is high and the output of the oscillator is allowed to pass through the AND gate to the output driver and output switch. The output switch then turns on and off storing energy in the inductor. When the output switch is on (low) energy is stored in the inductor; when the switch is off (high) the stored energy is dumped into the output capacitor which causes the output voltage to rise. When the output voltage is high enough to cause the comparator output to be low (inverting input voltage is above 0.22V) the AND gate is disabled and the output switch remains off (high). The output switch remains disabled until the output voltage falls low enough to cause the comparator output to go high. Figure 1. Typical Boost Regulator Waveforms Synchronization The SYNC pin is used to synchronize the MIC2571 to an external oscillator or clock signal. This can reduce system noise by correlating switching noise with a known system frequency. When not in use, the SYNC pin should be grounded to prevent spurious circuit operation. A falling edge at the SYNC input triggers a one-shot pulse which resets the oscillator. It is possible to use the SYNC pin to generate oscillator duty cycles from approximately 20% up to the nominal duty cycle. Current Limit Current limit for the MIC2571 is internally set with a resistor. It functions by modifying the oscillator duty cycle and frequency. When current exceeds 1.2A, the duty cycle is reduced (switch on-time is reduced, off-time is unaffected) and the corresponding frequency is increased. In this way less time is available for the inductor current to build up while maintaining the same discharge time. The onset of current limit is soft rather than abrupt but sufficient to protect the inductor and output switch from damage. Certain combinations of input voltage, output voltage and load current can cause the inductor to go into a continuous mode of operation. This is what happens when the inductor current can not fall to zero and occurs when: There is about 6mV of hysteresis built into the comparator to prevent jitter about the switch point. Due to the gain of the feedback resistor divider the voltage at VOUT experiences about 120mV of hysteresis for a 5V output. Appications Information Oscillator Duty Cycle and Frequency The oscillator duty cycle is set to 67% which is optimized to provide maximum load current for output voltages approximately 3x larger than the input voltage. Other output voltages are also easily generated but at a small cost in efficiency. The fixed oscillator frequency (options -1 and -2) is set to 20kHz. duty cycle Output Waveforms The voltage waveform seen at the collector of the output switch (SW pin) is either a continuous value equal to VIN or a switching waveform running at a frequency and duty cycle set by the oscillator. The continuous voltage equal to VIN happens when the voltage at the output (VOUT) is high enough to cause the comparator to disable the AND gate. In this state the output switch is off and no switching of the inductor occurs. When VOUT drops low enough to cause the comparator output to change to the high state the output switch is driven by the oscillator. See Figure 1 for typical voltage waveforms in a boost application. VOUT + VDIODE - VIN VOUT + VDIODE - VSAT Inductor Current Current "ratchet" without current limit Current limit threshold Continuous current Discontinuous current Time Figure 2. Current Limit Behavior MIC2571 6 1997 MIC2571 Micrel Capacitors It is important to select high-quality, low ESR, filter capacitors for the output of the regulator circuit. High ESR in the output capacitor causes excessive ripple due to the voltage drop across the ESR. A triangular current pulse with a peak of 500mA into a 200m ESR can cause 100mV of ripple at the output due the capacitor only. Acceptable values of ESR are typically in the 50m range. Inexpensive aluminum electrolytic capacitors usually are the worst choice while tantalum capacitors are typically better. Figure 4 demonstrates the effect of capacitor ESR on output ripple voltage. Figure 2 shows an example of inductor current in the continuous mode with its associated change in oscillator frequency and duty cycle. This situation is most likely to occur with relatively small inductor values, large input voltage variations and output voltages which are less than ~3x the input voltage. Selection of an inductor with a saturation threshold above 1.2A will insure that the system can withstand these conditions. Inductors, Capacitors and Diodes The importance of choosing correct inductors, capacitors and diodes can not be ignored. Poor choices for these components can cause problems as severe as circuit failure or as subtle as poorer than expected efficiency. OUTPUT VOLTAGE (V) 5.25 Inductor Current a. b. 5.00 c. 4.75 Time Figure 3. Inductor Current: a. Normal, b. Saturating and c. Excessive ESR 0 500 1000 TIME (s) 1500 Figure 4. Output Ripple Output Diode Finally, the output diode must be selected to have adequate reverse breakdown voltage and low forward voltage at the application current. Schottky diodes typically meet these requirements. Standard silicon diodes have forward voltages which are too large except in extremely low power applications. They can also be very slow, especially those suited to power rectification such as the 1N400x series, which affects efficiency. Inductor Behavior The inductor is an energy storage and transfer device. Its behavior (neglecting series resistance) is described by the following equation: Inductors Inductors must be selected such that they do not saturate under maximum current conditions. When an inductor saturates, its effective inductance drops rapidly and the current can suddenly jump to very high and destructive values. Figure 3 compares inductors with currents that are correct and unacceptable due to core saturation. The inductors have the same nominal inductance but Figure 3b has a lower saturation threshold. Another consideration in the selection of inductors is the radiated energy. In general, toroids have the best radiation characteristics while bobbins have the worst. Some bobbins have caps or enclosures which significantly reduce stray radiation. The last electrical characteristic of the inductor that must be considered is ESR (equivalent series resistance). Figure 3c shows the current waveform when ESR is excessive. The normal symptom of excessive ESR is reduced power transfer efficiency. Note that inductor ESR can be used to the designers advantage as reverse battery protection (current limit) for the case of relatively low output power one-cell designs. The potential for very large and destructive currents exits if a battery in a one-cell application is inserted backwards into the circuit. In some applications it is possible to limit the current to a nondestructive (but still battery draining) level by choosing a relatively high inductor ESR value which does not affect normal circuit performance. I = V x t L where: V = inductor voltage (V) L = inductor value (H) t = time (s) I = inductor current (A) If a voltage is applied across an inductor (initial current is zero) for a known time, the current flowing through the inductor is a linear ramp starting at zero, reaching a maximum value at the end of the period. When the output switch is on, the voltage across the inductor is: V1 = VIN - VSAT 1997 7 MIC2571 MIC2571 Micrel When the output switch turns off, the voltage across the inductor changes sign and flies high in an attempt to maintain a constant current. The inductor voltage will eventually be clamped to a diode drop above VOUT. Therefore, when the output switch is off, the voltage across the inductor is: Referring to Figure 1, it can be seen the peak input current will be twice the average input current. Rearranging the inductor equation to solve for L: L = V x t1 I V2 = VOUT + VDIODE - VIN For normal operation the inductor current is a triangular waveform which returns to zero current (discontinuous mode) at each cycle. At the threshold between continuous and discontinuous operation we can use the fact that I1 = I2 to get: L = x t1 duty cycle fOSC To illustrate the use of these equations a design example will be given: V1 t = 2 V2 t1 Assume: MIC2571-1 (fixed oscillator) VOUT = 5V This relationship is useful for finding the desired oscillator duty cycle based on input and output voltages. Since input voltages typically vary widely over the life of the battery, care must be taken to consider the worst case voltage for each parameter. For example, the worst case for t1 is when VIN is at its minimum value and the worst case for t2 is when VIN is at its maximum value (assuming that VOUT, VDIODE and VSAT do not change much). To select an inductor for a particular application, the worst case input and output conditions must be determined. Based on the worst case output current we can estimate efficiency and therefore the required input current. Remember that this is power conversion, so the worst case average input current will occur at maximum output current and minimum input voltage. MIC2571 2 x Average IIN(max) where t1 = V1 x t1 = V2 x t 2 Average IIN(max) = VIN(min) IOUT(max) =5mA VIN(min) = 1.0V efficiency = 75%. Average IIN(max) = 5V x 5mA = 33.3mA 1.0V x 0.75 1.0V x 0.7 2 x 33.3mA x 20kHz L = 525H Use the next lowest standard value of inductor and verify that it does not saturate at a current below about 75mA (< 2 x 33.3mA). L = VOUT x IOUT(max) VIN(min) x Efficiency 8 1997 MIC2571 Micrel Application Examples L1 D1 150H MBR0530 VOUT 5V/5mA 8 IN C1* 47F 16V 1V to 1.5V 1 Cell 1 SW MIC2571 5V 4 SYNC GND 7 C2 47F 16V 2 * Needed if battery is more than 4" away from MIC2571 U1 C1 C2 D1 L1 Micrel Sprague Sprague Motorola Coilcraft MIC2571-1BMM 594D476X0016C2T Tantalum ESR = 0.11 594D476X0016C2T Tantalum ESR = 0.11 MBR0530T1 DO1608C-154 DCR = 1.7 Example 1. 5V/5mA Regulator L1 D1 150H MBR0530 VOUT 3.3V/8mA 8 1 IN C1* 47F 16V 1V to 1.5V 1 Cell SW MIC2571 3.3V SYNC GND 7 5 C2 47F 16V 2 * Needed if battery is more than 4" away from MIC2571 U1 C1 C2 D1 L1 Micrel Sprague Sprague Motorola Coilcraft MIC2571-1BMM 594D476X0016C2T Tantalum ESR = 0.11 594D476X0016C2T Tantalum ESR = 0.11 MBR0530T1 DO1608C-154 DCR = 1.7 Example 2. 3.3V/8mA Regulator L1 D1 150H MBR0530 VOUT 12V/2mA 8 IN 1.0V to 1.5V 1 Cell C1* 47F 16V SW 1 R2 1M 1% MIC2571 FB 6 SYNC GND 7 2 C2 15F 25V R1 20k 1% * Needed if battery is more than 4" away from MIC2571 VOUT = 0.22V U1 C1 C2 D1 L1 Micrel Sprague Sprague Motorola Coilcraft (1 + R2/R1) MIC2570-2BMM 594D476X0016C2T Tantalum ESR = 0.11 594D156X0025C2T Tantalum ESR = 0.22 MBRA0530T1 DO1608C-154 DCR = 1.7 Example 3. 12V/40mA Regulator 1997 9 MIC2571 MIC2571 Micrel L1 D1 150H C3 47F 16V 8 IN C1* 47F 16V 1V to 1.5V 1 Cell SW 1 MIC2571 5V SYNC GND 7 2 C2 47F 16V 4 D2 MBR0530 * Needed if battery is more than 4" away from MIC2571 D3 MBR0530 U1 C1 C2 C3 C4 D1 D2 D3 L1 Micrel Sprague Sprague Sprague Sprague Motorola Motorola Motorola Coilcraft VOUT/+IOUT 5V/2mA MBR0530 C4 47F 16V R1 220k MIC2571-1BMM 594D476X0016C2T Tantalum ESR = 0.11 594D476X0016C2T Tantalum ESR = 0.11 594D476X0016C2T Tantalum ESR = 0.11 594D476X0016C2T Tantalum ESR = 0.11 MBR0530T1 MBR0530T1 MBR0530T1 DO1608C-154 DCR = 1.7 -VOUT/-IOUT -5V/2mA -IOUT +IOUT Example 4. 5V/2mA Regulator L1 D1 47H 1V to 1.5V 1 Cell MBRA140 Q1 2N3906 C1 100F 10V VOUT 5V/15mA 8 R1 51k IN 1 SW MIC2571 5V 4 SYNC GND 7 C2 100F 10V 2 Minimum Start-Up Supply Voltage VIN = 1V, ILOAD = 0A VIN = 1.2V, ILOAD = 15mA U1 Micrel MIC2571-1BMM C1 AVX TPSD107M010R0100 Tantalum ESR = 0.1 C2 AVX TPSD107M010R0100 Tantalum ESR = 0.1 D1 Motorola MBRA140T3 L1 Coilcraft DO3308P-473 DCR = 0.32 Example 5. 5V/15mA Regulator L1 1V to 1.5V 1 Cell D3 150H 1N4148 8 IN C1 47F 16V SW C1 15F 25V 1 R2 1.1M 1.1% MIC2571 FB 6 C2 0.1F SYNC GND 7 R1 20k 1% 2 D1 MBR0530 -VOUT = - 0.22V U1 C1 C2 C3 D1 D2 L1 Micrel Sprague Sprague Sprague Motorola Motorola Coilcraft (1+R2/R1) + 0.6V D2 MBR0530 MIC2571-2BM 594D476X0016C2T Tantalum ESR = 0.11 594D156X0025C2T Tantalum ESR = 0.22 594D156X0025C2T Tantalum ESR = 0.22 MBR0530T1 MBR0530T1 DO1608C-154 DCR = 1.7 R3 220k C2 15F 25V -VOUT -12V/2mA Example 6. -12V/2mA Regulator MIC2571 10 1997 MIC2571 Micrel Suggested Manufacturers List Inductors Capacitors Diodes Coilcraft 1102 Silver Lake Rd. Cary, IL 60013 PH (708) 639-2361 FX (708) 639-1469 AVX Corp. 801 17th Ave. South Myrtle Beach, SC 29577 PH (803) 448-9411 FX (803) 448-1943 General Instruments (GI) 10 Melville Park Rd. Melville, NY 11747 PH (516) 847-3222 FX (516) 847-3150 Coiltronics 6000 Park of Commerce Blvd. Boca Raton, FL 33487 PH (407) 241-7876 FX (407) 241-9339 Sanyo Video Components Corp. 2001 Sanyo Ave. San Diego, CA 92173 PH (619) 661-6835 FX (619) 661-1055 International Rectifier Corp. 233 Kansas St. El Segundo, CA 90245 PH (310) 322-3331 FX (310) 322-3332 Sprague Electric Motorola Inc. 3102 North 56th St. MS 56-126 Phoenix, AZ 85018 PH (602) 244-3576 FX (602) 244-4015 Sumida 637 E. Golf Road, Suite 209 Arlington Heights, IL PH (708) 956-0666 FX (708) 956-0702 Lower Main Street 60005Sanford, ME 04073 PH (207) 324-4140 Evaluation Board Layout Component Side and Silk Screen (Not Actual Size) Solder Side and Silk Screen (Not Actual Size) 1997 11 MIC2571 MIC2571 Micrel Package Information 0.199 (5.05) 0.187 (4.74) 0.122 (3.10) 0.112 (2.84) DIMENSIONS: INCH (MM) 0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.032 (0.81) 0.043 (1.09) 0.038 (0.97) 0.012 (0.30) R 0.012 (0.03) 0.0256 (0.65) TYP 0.008 (0.20) 0.004 (0.10) 5 MAX 0 MIN 0.007 (0.18) 0.005 (0.13) 0.012 (0.03) R 0.039 (0.99) 0.035 (0.89) 0.021 (0.53) 8-Pin MSOP (MM) MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. (c) 1997 Micrel Incorporated MIC2571 12 1997