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| CS8221 CS8221 Micropower 5V, 100mA Low Dropout Linear Regulator Description The CS8221 is a precision 5V, 100mA micropower voltage regulator with very low quiescent current (60A typical at 100A load). The 5V output is accurate within 2% and supplies 100mA of load current with a maximum dropout voltage of only 600mV. The regulator is protected against reverse battery, short circuit, over voltage, and over temperature conditions. The device can withstand 74V load dump transients making it suitable for use in automotive environments. Features s Low Quiescent Current (60A @ 100A load) s 5V, 2% Output s 100mA Output Current Capability s Fault Protection +74V Peak Transient Voltage -15V Reverse Voltage Short Circuit Thermal Shutdown Low Reverse Current (Output to Input) Absolute Maximum Ratings Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Internally Limited Transient Peak Voltage (60V Load Dump) . . . . . . . . . . . . . . . . . . . .-15V, 74V Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Internally Limited ESD Susceptibility (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . .2kV Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40C to 150C Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-55C to 150C Lead Temperature Soldering Reflow (SMD styles only) . . . . . .60 sec. max above 183C, 230C peak Package Options Block Diagram VOUT VIN Current Source (Circuit Bias) Over Voltage Shutdown 8L SO Narrow (Internally Fused Leads) VIN VOUT 1 Gnd Gnd Gnd Gnd D2PAK NC Sense Current Limit Sense Sense* 3L D2PAK Tab (Gnd) + Thermal Shutdown - Error Amplifier Bandgap Reference 1 Gnd 1. VIN 2. Gnd 3. VOUT * 8 Lead SO Narrow Consult factory for TO-92. Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi.com Web Site: www.cherry-semi.com Rev. 12/28/98 1 A Company CS8221 Electrical Characteristics: 6V VIN 26V, IOUT = 1mA, -40 TA 125C, -40 TJ 150C; unless otherwise specified. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT s Output Stage Output Voltage, VOUT Dropout Voltage (VIN-VOUT) Load Regulation Line Regulation Quiescent Current, (IQ) 9V Note 1: This parameter is guaranteed by design, but not parametrically tested in production. Package Lead Description PACKAGE LEAD # LEAD SYMBOL FUNCTION 8L SO Narrow (Internally Fused Leads) 1 2 3 4 3L D2PAK 1 3 VIN VOUT NC Sense Input voltage. 5V, 2%, 100mA output. No connection. Kelvin connection which allows remote sensing of the output voltage for improved regulation. If remote sensing is not required, connect to VOUT. Ground. 5,6,7,8 2 Gnd 2 CS8221 Circuit Description Voltage Reference and Output Circuitry Output Stage Protection The output stage is protected against overvoltage, short circuit and thermal runaway conditions (Figure 1). If the input voltage rises above 34V (typ), the output shuts down. This response protects the internal circuitry and enables the IC to survive unexpected voltage transients. Should the junction temperature of the power device exceed 180uC (typ) the power transistor is turned off. Thermal shutdown is an effective means to prevent die overheating since the power transistor is the principle heat source in the IC. VIN > 30V VOUT IOUT Load Dump Short Circuit Thermal Shutdown Figure 1. Typical Circuit Waveforms for Output Stage Protection. Application & Test Diagram VIN C1** 0.1mF VOUT CS8221 Sense* Gnd C2*** 10mF * 8 Lead SO Narrow only **C1 is required if regulator is distant from power source filter. ***C2 is required for stability. Application Notes Stability Considerations The output or compensation capacitor helps determine three main characteristics of a linear regulator: start-up delay, load transient response and loop stability. The capacitor value and type should be based on cost, availability, size and temperature constraints. A tantalum or aluminum electrolytic capacitor is best, since a film or ceramic capacitor with almost zero ESR can cause instability. The aluminum electrolytic capacitor is the least expensive solution, but, if the circuit operates at low temperatures (-25C to -40C), both the value and ESR of the capacitor will vary considerably. The capacitor manufacturers data sheet usually provides this information. The value for the output capacitor COUT shown in the test and applications circuit should work for most applications, however it is not necessarily the optimized solution. To determine an acceptable value for COUT for a particular application, start with a tantalum capacitor of the recommended value and work towards a less expensive alternative part. Step 1: Place the completed circuit with a tantalum capacitor of the recommended value in an environmental cham3 ber at the lowest specified operating temperature and monitor the outputs with an oscilloscope. A decade box connected in series with the capacitor will simulate the higher ESR of an aluminum capacitor. Leave the decade box outside the chamber, the small resistance added by the longer leads is negligible. Step 2: With the input voltage at its maximum value, increase the load current slowly from zero to full load while observing the output for any oscillations. If no oscillations are observed, the capacitor is large enough to ensure a stable design under steady state conditions. Step 3: Increase the ESR of the capacitor from zero using the decade box and vary the load current until oscillations appear. Record the values of load current and ESR that cause the greatest oscillation. This represents the worst case load conditions for the regulator at low temperature. Step 4: Maintain the worst case load conditions set in step 3 and vary the input voltage until the oscillations increase. This point represents the worst case input voltage conditions. Step 5: If the capacitor is adequate, repeat steps 3 and 4 with the next smaller valued capacitor. A smaller capaci- CS8221 Application Notes: continued tor will usually cost less and occupy less board space. If the output oscillates within the range of expected operating conditions, repeat steps 3 and 4 with the next larger standard capacitor value. Step 6: Test the load transient response by switching in various loads at several frequencies to simulate its real working environment. Vary the ESR to reduce ringing. Step 7: Remove the unit from the environmental chamber and heat the IC with a heat gun. Vary the load current as instructed in step 5 to test for any oscillations. Once the minimum capacitor value with the maximum ESR is found, a safety factor should be added to allow for the tolerance of the capacitor and any variations in regulator performance. Most good quality aluminum electrolytic capacitors have a tolerance of 20% so the minimum value found should be increased by at least 50% to allow for this tolerance plus the variation which will occur at low temperatures. The ESR of the capacitor should be less than 50% of the maximum allowable ESR found in step 3 above. Calculating Power Dissipation in a Single Output Linear Regulator The maximum power dissipation for a single output regulator (Figure 2) is: PD(max) = {VIN(max)VOUT(min)}IOUT(max)+VIN(max)IQ where: VIN(max) is the maximum input voltage, VOUT(min) is the minimum output voltage, IOUT(max) is the maximum output current for the application, and IQ is the quiescent current the regulator consumes at IOUT(max). Once the value of PD(max) is known, the maximum permissible value of RQJA can be calculated: RQJA = 150C - TA PD (2) (1) The value of RQJA can then be compared with those in the package section of the data sheet. Those packages with RQJA's less than the calculated value in equation 2 will keep the die temperature below 150C. In some cases, none of the packages will be sufficient to dissipate the heat generated by the IC, and an external heatsink will be required. Heat Sinks A heat sink effectively increases the surface area of the package to improve the flow of heat away from the IC and into the surrounding air. Each material in the heat flow path between the IC and the outside environment will have a thermal resistance. Like series electrical resistances, these resistances are summed to determine the value of RQJA: RQJA = RQJC + RQCS + RQSA (3) where: RQJC = the junctiontocase thermal resistance, RQCS = the casetoheatsink thermal resistance, and RQSA = the heatsinktoambient thermal resistance. RQJC appears in the package section of the data sheet. Like RQJA, it too is a function of package type. RQCS and RQSA are functions of the package type, heatsink and the interface between them. These values appear in heat sink data sheets of heat sink manufacturers. IIN VIN IOUT CS8221 VOUT IQ Figure 2. Single output regulator with key performance parameters labeled. 4 CS8221 Package Specification PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA D Lead Count 8L SO Narrow (internally fused leads) Metric Max Min 5.00 4.80 English Max Min .197 .189 Thermal Data RQJC RQJA typ typ 8 Lead SO Narrow (internally fused leads) 25 110 3 Lead D2PAK 4.2 10-50* uC/W uC/W *Depending on thermal properties of substrate. RQJA = RQJC + RQCA Surface Mount Narrow Body (D); 150 mil wide 4.00 (.157) 3.80 (.150) 6.20 (.244) 5.80 (.228) 0.51 (.020) 0.33 (.013) 1.27 (.050) BSC 1.75 (.069) MAX 1.57 (.062) 1.37 (.054) 1.27 (.050) 0.40 (.016) 0.25 (.010) 0.19 (.008) D REF: JEDEC MS-012 0.25 (0.10) 0.10 (.004) 5 CS8221 Package Specification 3 Lead D2PAK (DP) 10.31 (.406) 10.05 (.396) 1.68 (.066) 1.40 (.055) 1.40 (.055) 1.14 (.045) 8.53 (.336) 8.28 (.326) 15.75 (.620) 14.73 (.580) 2.74(.108) 2.49(.098) 1.40 (.055) 1.14 (.045) 0.91 (.036) 0.66 (.026) 2.54 (.100) REF .254 (.010) REF 2.79 (.110) 2.29 (.090) 4.57 (.180) 4.31 (.170) 0.10 (.004) 0.00 (.000) Ordering Information Part Number CS8221YDF8 CS8221YDFR8 CS8221YDP3 CS8221YDPR3 Rev. 12/28/98 Description 8L SO Narrow (internally fused leads) 8L SO Narrow (internally fused leads) (tape & reel) 3L D2PAK 3L D2PAK (tape & reel) 6 Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. (c) 1999 Cherry Semiconductor Corporation |
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