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CS8311 Micropower 10 V, 100 mA Low Dropout Linear Regulator with RESET and ENABLE
The CS8311 is a precision 10 V micropower voltage regulator with very low quiescent current (100 A typ at 100 A load). The 10 V output is accurate within 4.0% and supplies 100 mA of load current with a typical dropout voltage of only 400 mV. Microprocessor control logic includes an ENABLE input and an active RESET. The active RESET circuit includes hysteresis, and operates correctly at an output voltage as low as 1.0 V. The RESET function is activated during the power up sequence or during normal operation if the output voltage drops outside the regulation limits by more than 1.0 V typ. The logic level compatible ENABLE input allows the user to put the regulator into a shutdown mode where it draws only 20 A typical of quiescent current. The regulator is protected against reverse battery, short circuit, over voltage, and thermal overload conditions. The device can withstand load dump transients making it suitable for use in automotive environments. Features 10 V 4.0% Output Low 100 A Quiescent Current Active RESET ENABLE Input for ON/OFF and Active/Sleep Mode Control 100 mA Output Current Capability Fault Protection - +60 V Peak Transient Voltage - -15 V Reverse Voltage Short Circuit Thermal Overload * Low Reverse Current (Output to Input)
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SO-8 D SUFFIX CASE 751
8 1
PIN CONNECTIONS AND MARKING DIAGRAM
VOUT VOUTSense ENABLE GND A WL, L YY, Y WW, W 1 8311 ALYWX 8 VIN NC NC RESET
* * * * * *
= Assembly Location = Wafer Lot = Year = Work Week
ORDERING INFORMATION
Device CS8311YD8 CS8311YDR8 Package SO-8 SO-8 Shipping 95 Units/Rail 2500 Tape & Reel
(c) Semiconductor Components Industries, LLC, 2001
1
April, 2001 - Rev. 5
Publication Order Number: CS8311/D
CS8311
VOUT VIN Current Source (Circuit Bias) Over Voltage Shutdown
ENABLE Current Limit Sense VOUTSense + Thermal Protection - Error Amplifier
Bandgap Reference
RESET + - Reset Comparator GND
Figure 1. Block Diagram ABSOLUTE MAXIMUM RATINGS*
Rating VIN Peak Transient Voltage (46 V Load Dump @ VIN = 14 V) ENABLE, RESET ESD Susceptibility (Human Body Model) Junction Temperature Range Storage Temperature Range Lead Temperature Soldering: 1. 60 second maximum above 183C. *The maximum package power dissipation must be observed. Reflow (SMD styles only) (Note 1.) Value 38 60 -0.3 to +10.4 2.0 -40 to +150 -55 to +150 230 peak Unit V V V kV C C C
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CS8311
ELECTRICAL CHARACTERISTICS (11 V VIN 26 V; IOUT = 1.0 mA; -40 TA 125, -40C TJ 150C;
unless otherwise specified.) Characteristic Output Stage Output Voltage, VOUT Dropout Voltage (VIN - VOUT) Load Regulation Line Regulation Quiescent Current, (IQ) Active Mode 11 V < VIN < 26 V, 100 A IOUT 100 mA IOUT = 100 mA IOUT = 100 A VIN = 14 V, 100 A IOUT 100 mA 11 V < V < 26 V, IOUT = 1.0 mA IOUT = 100 A IOUT = 50 mA IOUT = 100 mA VOUT = OFF, VIN = 12 V, VENABLE = 2.0 V 14 VIN 26 V, IOUT = 100 mA, f = 120 Hz - VOUT = 0 V VOUT 1.0 V VOUT = 5.0 V, VIN = 0 V 9.60 - - - - - - - - 60 105 25 30 - 10.00 400 100 5.0 5.0 100 4.0 12 20 75 200 125 34 100 10.40 600 150 100 100 250 6.0 20 50 - - - 38 250 V mV mV mV mV A mA mA A dB mA mA V A Test Conditions Min Typ Max Unit
Quiescent Current, (IQ) Sleep Mode Ripple Rejection Current Limit Short Circuit Output Current Overvoltage Shutdown Reverse Current ENABLE Input (ENABLE) Threshold High Threshold Low Input Current Reset Function (RESET) RESET Threshold High (VRH) RESET Threshold Low (VRL) RESET Hysteresis Reset Output Leakage RESET = High Output Voltage Low (VRLO) Output Voltage Low (VRPEAK)
(VOUT OFF) (VOUT ON) VENABLE = 2.4 V
- 0.6 -
1.4 1.4 30
2.0 - 100
V V A
VOUT Increasing VOUT Decreasing (High - Low) VOUT VRH RRESET = 10 k, 1.0 V VOUT VRL RRESET = 10 k, VOUT, Power up, Power down
8.50 8.30 50 - - -
9.00 8.90 100 - 0.1 0.6
VOUT - 0.50 VOUT - 0.45 200 25 0.4 1.0
V V mV A V V
PACKAGE LEAD DESCRIPTION
PACKAGE LEAD # SO-8 1 2 3 4 5 6, 7 8 LEAD SYMBOL VOUT VOUTSense ENABLE GND RESET NC VIN 10 V, 4.0%, 100 mA output. Kelvin connection which allows remote sensing of output voltage for improved regulation. If remote sensing is not required, connect to VOUT. Logic level switches output off when toggled HIGH. Ground. All GND leads must be connected to Ground. Active reset (accurate to VOUT 1.0 V). No connection. Input voltage. FUNCTION
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CS8311
CIRCUIT DESCRIPTION
VOLTAGE REFERENCE AND OUTPUT CIRCUITRY Output Stage Protection ENABLE Function
The output stage is protected against overvoltage, short circuit and thermal runaway conditions (Figure 2).
> 30 V VIN VOUT
The ENABLE function switches the output transistor ON and OFF. When the voltage on the ENABLE lead exceeds 1.4 V typ, the output pass transistor turns off, leaving a high impedance facing the load. The IC will remain in Sleep mode, drawing only 50 A (max), until the voltage on this input drops below the ENABLE threshold.
RESET Function
IOUT
Load Dump
Current Limit
Short Circuit
Figure 2. Typical Circuit Waveforms for Output Stage Protection
A RESET signal (low voltage) is generated as the IC powers up until VOUT is within 1.0 V of the regulated output voltage, or when VOUT drops out of regulation, and is lower than 1.1 V below the regulated output voltage. A hysteresis of 50 mV is included in the function to minimize oscillations. The RESET output is an open collector NPN transistor, controlled by a low voltage detection circuit. The circuit is functionally independent of the rest of the IC thereby guaranteeing that the RESET signal is valid for VOUT as low as 1.0 V.
VOUT 5.0 V to P and System Power RRST COUT to P RESET Port CRST
If the input voltage rises above 30 V (e.g. load dump), 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 180C (typ) the load current capability is reduced thereby preventing thermal overload. This thermal management function is an effective means to prevent die overheating since the load current is the principle heat source in the IC.
REGULATOR CONTROL FUNCTIONS
CS8311
RESET
Figure 4. RC Network for RESET Delay
The CS8311 contains two microprocessor compatible control functions: ENABLE and RESET (Figure 3).
For 11 V < VIN < 26 V
An external RC network on the lead (Figure 4) provides a sufficiently long delay for most microprocessor based applications. RC values can be chosen using the following formula:
RTOTCRST + -tDelay ln
VT*VOUT VRST*VOUT
VIN ENABLE VIN(H) VRH ON VRL OFF (1) VRPEAK RESET VRLO (1) = No Reset Delay Capacitor (2) = With Reset Delay Capacitor (2) VRPEAK
VOUT
where: RRST = RESET Delay resistor RIN = P port impedance RTOT = RRST in parallel with RIN CRST = RESET Delay capacitor tDelay = desired delay time VRST = VSAT of RESET lead (0.7 V @ turn - ON) VT = RESET threshold.
Figure 3. Circuit Waveform
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CS8311
APPLICATION NOTES
10 V, 100 mA VBAT 0.1 F 500 k VIN VOUT To Load COUT
CS8311
ENABLE GND RESET
RRST
To P CRST
Q1 100 k 500 k SWITCH 100 k
To P I/O
Figure 5. Microprocessor Control of CS8311 Using External Switching Transistor Q1
The circuit depicted in Figure 5 lets the system control its power source, the CS8311 regulator. A SWITCH (potentially an I/O port on microprocessor) is used to drive the base of Q1. When Q1 is driven into saturation, the voltage on the ENABLE lead falls below its lower threshold. The regulator's output is enabled. When the drive current is removed, the voltage on the ENABLE lead rises, the output is switched off and the IC moves into Sleep mode where it draws 50 A (max). By coupling these two controls with the ENABLE lead, the system has added flexibility. Once the system is running, the state of the SWITCH is irrelevant as long as the I/O port continues to drive Q1. The microprocessor can turn off its own power by withdrawing drive current, once the SWITCH is open. This software control at the I/O port allows the microprocessor to finish key housekeeping functions before power is removed. The logic options are summarized in Table 1.
Table 1. Logic Control of CS8311 Output
Microprocessor I/O Drive ON Switch Closed Open OFF Closed Open ENABLE LOW LOW LOW HIGH Output ON ON ON OFF
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.
VIN CIN* 0.1 F VOUT CS8311 RESET ENABLE RRST COUT** 10 F
*CIN required if regulator is located far from the power supply filter. *COUT required for stability. Capacitor must operate at minimum temperature expected.
Figure 6. Test and Application Circuit Showing Output Compensation
The I/O port of the microprocessor typically provides 50 A to Q1. In automotive applications the SWITCH is connected to the ignition switch.
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 Figure 6 should work for most applications, however it is not necessarily the optimized solution.
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CS8311
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 chamber 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 capacitor 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: Raise the temperature to the highest specified operating temperature. 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
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 RJA can be calculated:
RQJA + 150C * TA PD
(2)
The value of RJA can then be compared with those in the package section of the data sheet. Those packages with RJA'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.
IIN VIN IOUT
SMART REGULATOR(R)
Control Features
VOUT
IQ
Figure 7. Single Output Regulator With Key Performance Parameters Labeled 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 RJA.
RQJA + RQJC ) RQCS ) RQSA
(3)
The maximum power dissipation for a single output regulator (Figure 7) is:
PD(max) + VIN(max) * VOUT(min) IOUT(max) ) VIN(max)IQ
(1)
where: RJC = the junction-to-case thermal resistance, RCS = the case-to-heatsink thermal resistance, and RSA = the heatsink-to-ambient thermal resistance. RJC appears in the package section of the data sheet. Like RJA, it too is a function of package type. RCS and RSA are functions of the package type, heatsink and the interface between them. These values appear in heat sink data sheets of heat sink manufacturers.
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CS8311
PACKAGE DIMENSIONS
SO-8 D SUFFIX CASE 751-07 ISSUE W
-X- A
8 5
B
1 4
S
0.25 (0.010)
M
Y
M
-Y- G C -Z- H D 0.25 (0.010)
M SEATING PLANE
K
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. DIM A B C D G H J K M N S MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0_ 8_ 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0_ 8_ 0.010 0.020 0.228 0.244
N
X 45 _
0.10 (0.004)
M
J
ZY
S
X
S
PACKAGE THERMAL DATA Parameter RJC RJA Typical Typical SO-8 45 165 Unit C/W C/W
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CS8311
SMART REGULATOR is a registered trademark of Semiconductor Components Industries, LLC (SCILLC).
ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
PUBLICATION ORDERING INFORMATION
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CS8311/D

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