RC4391 FAIRCHILD | Alldatasheet
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PRODUCT SPECIFICATION RC4391 Pin Assignments LBR LBD C X GND VFB VREF +V S LX 65-3471-02 Absolute Maximum Ratings Note: 1. The maximum allowable supply voltage (+VS) in inverting applications will be reduced by the value of the negative output voltage, unless an external power transistor is used in place of Q1. Thermal Characteristics Parameter Conditions Min Typ Max Unit Internal Power Dissipation 500 mW Supply Voltage 1 (Pin 6 to Pin 4 or Pin 6 to Pin 5) +30 V Operating Temperature RC4391 0 70 °C RV4391 -25 85 °C RM4391 -55 125 °C Storage Temperature -65 150 °C Junction Temperature PDIP, SOIC 125 °C CerDIP 175 °C Switch Current (IMAX ) Peak 375 mA PD TA <50˚C PDIP 468 mW CerDIP 833 mW SOIC 300 mW Lead Soldering Temperature (10 seconds) 300 °C 8-Lead Plastic DIP 8-Lead Ceramic DIP Small Outline SO-8 Therm. Res q JC —4 5 °C/W — Therm. Res. qJA 160°C/W 150 °C/W 240 °C/W For TA >50˚C Derate at 6.25 mW/ °C 8.33 mW/ °C 4.17 mW/ °C Pin Descriptions Pin Number Pin Function Description
1 Low Battery Resistor (LBR)
2 Low Battery Detector (LBD)
3 Timing Capacitor (C
4 Ground
5 External Inductor (L
6 +Supply Voltage (+V S) 7 +1.25V Reference Voltage (V REF )
8 Feedback Voltage (V FB )
RC4391 PRODUCT SPECIFICATION
Electrical Characteristics
(VS = +6.0V, over the full operating temperature range unless otherwise noted) Note: 1. The maximum allowable supply voltage (+VS) in inverting applications will be reduced by the value of the negative output voltage, unless an external power transistor is used. Symbol Parameters Condition Min Typ Max Units +VS Supply Voltage (Note 1) 4.0 30 V ISY Supply Current V S = +25V 300 500 mA VREF Reference Voltage 1.13 1.25 1.36 V VOUT Output Voltage V OUT nom = -5.0V -5.5 -5.0 -4.5 V VOUT nom = -15V -16.5 -15.0 -13.5 LI1 Line Regulation V OUT nom = -5.0V, %V OUT C X = 150pF VS = +5.8V to +15V 2.0 4.0 VOUT nom = -15V, C X = 150pF VS = +5.8V to +15 1.5 3.0 L01 Load Regulation V OUT nom = -5.0V, %V OUT C X = 350pF, VS = +4.5V, PLOAD = 0mW to 75mW 0.2 0.5 VOUT nom = -15V, C X = 350pF, VS = +4.5V, PLOAD = 0mW to 75mW 0.2 0.3 ICO Switch Leakage Current Pin 5 = -20V 0.1 30 mA
PRODUCT SPECIFICATION RC4391 (VS = +6.0V, TA = +25°C unless otherwise noted) Symbol Parameters Condition Min Typ Max Units ISY Supply Voltage V S = +4.0V, 170 250 mA No External Loads V S = +25V 300 500 No External Loads VOUT Output Voltage V OUT nom = -5.0V -5.35 -5.0 -4.65 V VOUT nom = -15V -15.85 -15.0 -14.15 LI1 Line Regulation V OUT nom = -5.0V %V OUT C X = 150pF, 1.5 3.0 VS = +5.8V to +15V VOUT nom = -15V, C X = 150pF 1.0 2.0 VS = +5.8V to +15V L01 Load Regulation V OUT nom = -5.0V, %V OUT C X = 350pF, VS = +4.5V, 0.2 0.4 PLOAD = 0mW to 75mW VOUT nom = -15V, C X = 350pF, VS = +4.5V, 0.07 0.14 PLOAD = 0mW to 75mW VREF Reference Voltage 1.18 1.25 1.32 V ISW Switch Current Pin 5 = 5.5V 75 100 mA ICO Switch Leakage Current Pin 5 = -24V 0.01 5.0 mA ICX Cap. Charging Current Pin 3 = 0V 6.0 10 14 mA ILBDL LBD Leakage Current Pin 1 = 1.5V, Pin 2 = 6.0V 0.01 5.0 mA ILBD0 LBD On Current Pin 1 = 1.1V, Pin 2 = 0.4V 210 600 mA ILBRB LBR Bias Current Pin 1 = 1.5V 0.7 mA
- Select an operating frequency and timing capacitor value
- Find the maximum on time T
- Calculate the peak inductor current IMAX (if this value
- Find an inductance value for LX:
and have a current rating equal to IMAX . Figure 12. Step-Down Regulator Waveforms
- Select an operating frequency.
- Determine the maximum on time TON as in the inverting
- Select an operating frequency based on efficiency and
- Build the circuit and apply the worst case conditions to
current at the desired output voltage.
- Adjust the inductor value down until the desired output
cover manufacturing tolerances.
- Check the output voltage with an oscilloscope for ripple,
- If the efficiency is poor, go back to Step 1 and start over.
capacitor value or start over. provided later in this datasheet. linearity at the peaks (a sign of saturation). as the voltage dependent oscillator circuit of Figure 18. Figure 13. Low Battery Detector
Figure 9. Inverting High Power Application power, the RC4193 can be used for step-sown applications. a schematic of this medium power step-down application. iting. Figure 19 shows how this is applied.
PRODUCT SPECIFICATION RC4391 Simplified Schematic Diagram 65-6364 +V S 540K Q34 1.1 Q33 0.9 Q32 0.9 Q31 0.9 Q35 Q36 C X (3) Q27 10X 10K Q19 0.1 Q18 0.1 Q17 0.1 Q3B 0.5 LBD (2) LBR (1) Q3A 0.5 Q10Q4B 0.6 0.3 (6) Q6Q5 25 pF 3KQ7 8.2K Q45 Q46 76K 60K (7) VREF R10 50K 150K D7 D8 Q16 Q15Q14 Q24 Q25 Q26 40XD17 D18 Q22 D16 R6 20K R7 10K Q28 Q29 50X Q37 Q38 Q39 Q40 D13 D14 Q43 D12 (4) GND Q42 2XQ13 Q41 D10 (5) LX (8) VFB Q20 Q21 D15 Q23 Q44 Q12Q11 R11 160K
RC4391 PRODUCT SPECIFICATION ILX -IMAX Time ILX -IMAX Time ILX -IMAX Time Troubleshooting Chart Symptom Possible Problems Draws excessive supply current on star-up. Inductance value too low. Output frequency (FO ) too low. Combination of low resistance inductor and high value filter capacitor — needs current limiting circuit (Figure 13). Output voltage is low. Inductance value too high for F O or core saturating. Inductor "sings" with audible hum. Not potted well or bolted loosely. L X pin appears noisy — scope will not synchronize. Normal operating condition. Inductor is saturating: 1. Core too small. 2. Core too hot. 3. Operating frequency too low. Inductor current shows nonlinear waveform. Waveform has resistive component: 1. Wire size too small. 2. Power transistor lacks base drive. 3. Components not rated high enough. 4. Battery has high series resistance. Inductor current shows nonlinear waveform. External transistor lacks base drive or beta is too low. Inductor current is linear until high current is reached. Poor efficiency. Core saturating. Diode or transistor: 1. Not fast enough. 2. Not rated for current level (high V CE SAT). High series resistance. Operating frequency too high. Motorboating (erratic current pulses). Loop stability problem — needs feedback from V OUT to VFB (pin 8), 100pF to 1000pF
- Pot cores can be easily air-gapped. The length of the
- Electromagnetic interference (EMI) is kept to a
tor value is decreased, then the core can be made smaller. before saturation )to increase.
- From the application requirement, determine the
inductor value (L) and the required peak current (IMAX ).
- Observe the curves of the design aid graph and determine
- Note the approximate air gap at IMAX for the selected
- If the required inductance is equal to the indicated value
easily wound in cores winding area.
- If the required inductance is less than the value indicated
Figure 22. Inductor Design Aid
24 Gauge
70 Turns
26 Gauge
28 Gauge
60 Turns
30 Gauge
50 Turns
use up the leftover winding area and reduce resistive losses.
- Wind and gap the core as per calculations, and measure
the number of turns may be necessary.
- After the operation in circuit has been checked,
recommended by the manufacturer. be used for any core geometry, such as an E-E core.
5083 Kings Highway
186 Wood Avenue South
201 Stackpole Street
Figure 23. Inductor Current Waveforms
RC4391 PRODUCT SPECIFICATION Mechanical Dimensions 8-Lead Ceramic DIP Package A — .200 — 5.08 Symbol Inches Min. Max. Min. Max. Millimeters Notes b1 .014 .023 .36 .58 .065 1.65b2 .045 1.14 c1 .008 .015 .20 .38 E .220 .310 5.59 7.87 e .100 BSC 2.54 BSC L .125 .200 3.18 5.08 .015 .060 .38 1.52 .005 — .13 — 2, 8 5, 9 eA .300 BSC 7.62 BSC 7 Q 90¡ 105¡ 90¡ 105¡a D — .405 — 10.29 Notes: Index area: a notch or a pin one identification mark shall be located adjacent to pin one. The manufacturer's identification shall not be used as pin one identification mark. The minimum limit for dimension "b2" may be .023 (.58mm) for leads number 1, 4, 5 and 8 only. Dimension "Q" shall be measured from the seating plane to the base plane. This dimension allows for off-center lid, meniscus and glass overrun. The basic pin spacing is .100 (2.54mm) between centerlines. Each pin centerline shall be located within ±.010 (.25mm) of its exact longitudinal position relative to pins 1 and 8. Applies to all four corners (leads number 1, 4, 5, and 8). "eA" shall be measured at the center of the lead bends or at the centerline of the leads when "a" is 90¡. All leads – Increase maximum limit by .003 (.08mm) measured at the center of the flat, when lead finish applied. Six spaces. Note 1 D E Q A e L eA c1a
PRODUCT SPECIFICATION RC4391 Mechanical Dimensions (continued) 8-Lead Plastic DIP Package A — .210 — 5.33 Symbol Inches Min. Max. Min. Max. Millimeters Notes A1 .015 — .38 — .022 .56B .014 .36 B1 .045 .070 1.14 1.78 D .348 .430 8.84 10.92 .300 .325 7.62 8.26 .240 .280 6.10 7.11 E e — .430 — 10.92 .005 — .13 — A2 .115 .195 2.93 4.95 .100 BSC 2.54 BSC eB .115 .160 2.92 4.06L 8¡ 8¡ 5N C .008 .015 .20 .38 Notes: Dimensioning and tolerancing per ANSI Y14.5M-1982. "D" and "E1" do not include mold flashing. Mold flash or protrusions shall not exceed .010 inch (0.25mm). Terminal numbers are for reference only. "C" dimension does not include solder finish thickness. Symbol "N" is the maximum number of terminals. D e B A L 5 8 E eB C
RC4391 PRODUCT SPECIFICATION Mechanical Dimensions (continued) 8-Lead SOIC Package D A – C – ccc C LEAD COPLANARITY SEATING PLANEe B L h x 45¡ C a EH A .053 .069 1.35 1.75 Symbol Inches Min. Max. Min. Max. Millimeters Notes A1 .004 .010 0.10 0.25 .020 0.51B .013 0.33 C .008 .010 0.20 0.25 E .150 .158 3.81 4.01 e .228 .244 5.79 6.20 .010 .020 0.25 0.50 H .050 BSC 1.27 BSC h L .016 .050 0.40 1.27 0¡ 8¡ 0¡ 8¡ N8 8 a ccc .004 0.10—— D .189 .197 4.80 5.00 Notes: Dimensioning and tolerancing per ANSI Y14.5M-1982. "D" and "E" do not include mold flash. Mold flash or protrusions shall not exceed .010 inch (0.25mm). "L" is the length of terminal for soldering to a substrate. Terminal numbers are shown for reference only. "C" dimension does not include solder finish thickness. Symbol "N" is the maximum number of terminals.
PRODUCT SPECIFICATION RC4391 5/20/98 0.0m 001 Stock#DS30004391 Ó 1998 Fairchild Semiconductor Corporation LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 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 (c) 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 of the user. 2. A critical component in 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. www.fairchildsemi.com O rdering Information Part Number Package Operating Temperature Range RC4391N 8 Lead Plastic DIP 0˚C to +70°C RC4391M 8 Lead Plastic SOIC 0˚C to +70°C RV4391N 8 Lead Plastic DIP -25°C to +85°C RM4391D 8 Lead Ceramic DIP -55˚C to +125°C