Order this document by MC33468/D The MC33468 is a micropower step–up switching voltage regulator, specifically designed for handheld and pager applications, to provide a regulated output voltage using a minimum of external parts. This device features a quiescent bias current of 3.0 µA typical. The MC33468 features a highly accurate voltage reference, an error amplifier, an oscillator, a variable frequency modulation (VFM) controller, a drive pin (EXT) for an external transistor, and feedback resistors. The Vout pin is fixed at 2V in the IC. The output of the converter with an inductor, a diode, a capacitor, a drive transistor, and feed–back resistors can have an output of 30V. VARIABLE FREQUENCY MICROPOWER DC–to–DC CONVERTER SEMICONDUCTOR TECHNICAL DATA MC33468 Features: • Low Quiescent Bias Current of 3.0 µA • • • • • High Output Voltage Accuracy of ±2.5% 5 Low Startup Voltage of 0.8 V at No Load Output Voltage Set With External Resistors 1 Operating Temperature Range: –40°C to +85°C Surface Mount Package N SUFFIX PLASTIC PACKAGE CASE 1212 (SOT–23–5) ORDERING INFORMATION Device Output Voltage Marking Reel Size Tape Width Quantity MC33468SN–20ATR 2.0 0KXX* 7” 8 mm 3000 * “XX” denotes the lot number. PIN DESCRIPTION ÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Pin No. Symbol 1 GND Ground 2 VDD Input 3 EXT External Transistor Drive 4 NC No Connection 5 VOUT PIN CONNECTIONS Description Voltage Output Pin (Fixed at 2V) Ground 1 Vdd 2 EXT 3 5 VOUT 4 N/C (Top View) Representative Block Diagram 2 5 VDD 3 VOUT Drive EXT Oscillator Vref 1 MOTOROLA ANALOG IC DEVICE DATA Gnd 1 MC33468 MAXIMUM RATINGS (TC = 25°C, unless otherwise noted.) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ Symbol Value Unit Power Supply Voltage (Transient) VDD 12 V Power Supply Voltage (Operating) VDD 10 V External Pin Voltage VEXT –0.3 to VDD + 0.3 V EXT Pin Source/Sink Current IEXT 50/50 mA 150 667 mW °C/W Operating Junction Temperature PD RθJA TJ 125 °C Operating Ambient Temperature TA –40 to +85 °C Tstg –55 to +125 °C Rating Power Dissipation and Thermal Characteristics N Suffix, Plastic Package Case 1212 (SOT–23–5) Maximum Power Dissipation @ TA = 250°C Thermal Resistance, Junction–to–Air Storage Temperature Range ELECTRICAL CHARACTERISTICS (VDD = 1.9 V, TA = 25°C, unless otherwise noted.) Characteristic Symbol Min Typ Max Note1 Unit ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ OSCILLATOR Frequency fosc – 180 – kHz B Oscillator Minimum Supply Voltage (IO = 0 mA) VDD – 0.7 0.8 V B D 65 75 – % B Isource Isink 1.5 – – mA C 1.5 – – mA D VOUT IQ 1.950 2.000 2.050 V – 15 25 µA A A Oscillator Duty Cycle EXT OUTPUT ON State Source Current (VEXT = GND) OFF State Sink Current (VEXT = 1.9 V) TOTAL DEVICE Output Voltage Quiescent Bias Current (VOUT = 1.9 V, IO = 0 mA) Quiescent Bias Current (VOUT = 2.1 V, IO = 0 mA) IQ RVout Internal Resistor (VOUT to GND) DVOUT DTA Output Voltage Temperature Coefficient IOUT = 10 mA, –40°C ≤ TA ≤ 85°C – 3.0 5.0 µA 2.0 – – MW – ±50 – ppm/oc E 1. Indicates test circuits shown on next page. Figure 1. Output Voltage versus Output Current Figure 2. Efficiency versus Output Current 80 Vin = 3.6 V 70 35 EFFICIENCY VOUT , OUTPUT VOLTAGE (V) 40 30 60 50 40 25 30 20 0 20 40 IOUT, OUTPUT CURRENT (mA) 60 20 Vin = 3.6 V 0 20 Motorola, Inc. 1999 2 40 60 IOUT, OUTPUT CURRENT (mA) Rev 1, 09/1999 MOTOROLA ANALOG IC DEVICE DATA MC33468 A B VDD VDD VOUT A VOUT A EXT EXT GND GND Oscilloscope C D VDD VDD VOUT VOUT EXT EXT GND GND E VDD VOUT A EXT GND Figure 3. Test Circuit Schematics MOTOROLA ANALOG IC DEVICE DATA 3 MC33468 DEFINITIONS on–time of the transistor switch. During the off–time of the transistor switch, the inductor current ramps down to zero and remains at zero until another switching cycle begins. Since the VDD pin is connected to the input no external startup circuit is needed. Quiescent Bias Current – Current which is used to operate the switching regulator chip and is not delivered to the load. Leakage Current – Current drawn through a transistor junction, under a specified collector voltage, when the transistor is off. Oscillator The oscillator frequency, is internally programmed to 180 kHz. The duty ratio of the oscillator is designed for a constant value of 0.75 nominal. Hence the nominal on–time of the power switch is: 0.75 D ton 4.16 µs f osc (180 kHz) FUNCTIONAL DESCRIPTION Introduction The MC33468 is a monolithic power switching regulator optimized for dc–to–dc converter applications where power drain must be minimized. The MC33468 uses Variable Frequency Modulation to step up the input DC voltage to a higher accurate output voltage. Potential applications include low power consumer products and battery powered portable products. Typical application circuits are shown in Figure 4. + + + Feedback Comparator The output voltage is sensed and fed to a high speed comparator noninverting input through an internal resistive divider. The comparator inverting input is connected to an internally trimmed reference. With a voltage mode ripple converter operating under normal conditions, output switch conduction is initiated and terminated by the oscillator, off–time is controlled by the high speed voltage feedback comparator. Operating Description The MC33468 converter operates as a fixed on–time, variable off–time voltage mode ripple regulator. Operation is intended to be in the discontinuous mode, where the inductor current ramps up to a peak value which is greater than or equal to twice the value of the dc input current during the Figure 4. Typical 2.0 V Application with BJT VOUT VDD VIN VOUT EXT Gnd Figure 5. Design Equations for Step–Up Calculation Equation ton D f osc L t (n)(VinP ) (ton) IL(avg) IL(pk) 2 (V in * O Iin V sat)(t on) L Vripple(pp) [ (ton)(I ) O (C ) O The following converter design characteristics must be chosen: Vin – Nominal Operating dc input voltage VO – Desired dc output voltage IO – Desired dc output current Vripple(pp) – Desired peak–to–peak output ripple voltage. For best performance the ripple voltage should be kept to a low value since it directly affects regulation. Capacitor CO should have a low equivalent series resistance (ESR). NOTE: 1. Vsat – Saturation voltage of the switching transistor. n – Estimated circuit efficiency. 4 MOTOROLA ANALOG IC DEVICE DATA MC33468 Figure 6. Typical 2.0 V Application with MOSFET VOUT VDD VOUT VIN EXT GND If input voltage is high enough, higher efficiency may be obtained by using a MOSFET as the switch transistor, in which no gate resistor or capacitor is needed. MOSFET and BJT voltage rating (VDS and VCE) should be high enough to allow for spikes in voltage. Figure 7. Typical Application for Output Voltages Over 2.0 V L1 D1 VOUT R1 VDD (2.0 V) VOUT VIN COUT EXT Q1 Inductor (L1) Diode (D1) Capacitor (COUT) Transistor (Q1) Resistor (R1) Resistor (R2) When choosing the output capacitor, ensure that the capacitor voltage is higher than Vout. Select an inductor with low DC resistance and high saturation. A Schottky diode is recommended for a lower voltage drop and faster switching. MOTOROLA ANALOG IC DEVICE DATA R2 GND CD54 (15 mH) MBRD540T1 47 mF (Tantalum type) MMFT3055VL 150 kW 10 kW Use external resistors that are much smaller resistance than the resistance internal to the IC (minimum of 2 MW). When R1 is much less than the internal resistance, the error is minimized. 5 MC33468 OUTLINE DIMENSIONS N SUFFIX PLASTIC PACKAGE CASE 1212–01 (SOT–23) ISSUE O A 5 E 1 A2 0.05 S B D NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. DATUM C IS A SEATING PLANE. A1 DIM A1 A2 B C D E E1 e e1 L L1 4 2 L 3 E1 L1 B C 5X 0.10 M C B S A C S e e1 MILLIMETERS MIN MAX 0.00 0.10 1.00 1.30 0.30 0.50 0.10 0.25 2.80 3.00 2.50 3.10 1.50 1.80 0.95 BSC 1.90 BSC 0.20 ––– 0.45 0.75 Recommended Footprint for Surface Mount Applications 0.7 MAX. 1.0 2.4 0.95 0.95 1.9 (Unit: mm) SOT–23–5 6 MOTOROLA ANALOG IC DEVICE DATA MC33468 NOTES MOTOROLA ANALOG IC DEVICE DATA 7 MC33468 Motorola reserves the right to make changes without further notice to any products herein. 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