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CS8391
CS8391
5V/250mA, 5V/100mA Micropower Low Dropout Regulator with ENABLE
Description
The CS8391 is a precision, dual 5V micropower linear voltage regulator. The switched primary output (VOUT1) supplies up to 250mA while the secondary (VOUT2) is capable of supplying 100mA. Both outputs have a maximum dropout voltage of 600mV and low reverse current. Quiescent current drain is typically 150A when supplying 100A from each output. The ENABLE input provides logic level control of the primary output. With the primary output disabled, quiescent current drain is typically 100A when supplying 100A from the secondary output. The CS8391 is extremely robust with protection provided for reverse battery, short circuit, and overtemperature on both outputs. The CS8391 is available in a 5-lead D2PAK.
Features
s 5V, 250mA Primary Output s 5V, 100mA Secondary Output s 3% Tolerance, Both Outputs s ON/OFF Control for Primary Output s Low Quiescent Current Drain (100A VOUT2) s Low Reverse Current s Protection Features Reverse Battery (-15V) Short Circuit Overtemperature
Absolute Maximum Ratings Input Voltage.....................................................................................-15V to 45V Power Dissipation .................................................................Internally Limited Operating Temperature Range................................................-40C to +125C Maximum Junction Temperature ...........................................-40C to +150C Storage Temperature Range ....................................................-55C to +150C Electrostatic Discharge (Human Body Model) ..........................................4kV Lead Temperature Soldering Wave Solder (through hole styles only)..........10 sec. max, 260C peak Reflow (SMD styles only)...........60 sec. max above 183C, 230C peak Block Diagram
Primary Output VIN VOUT1
Package Options
5 Lead D2PAK Tab (Gnd)
*
ENABLE Current Limit + Bandgap Reference *Note: Internally connected on 5 leaded package. + Thermal Shutdown + Gnd VOUT1Sense
1
1. VIN 2. VOUT1 3. Gnd 4. VOUT2 5. ENABLE
Secondary Output VOUT2
*
Current Limit VOUT2Sense
Consult factory for 8L and 16L SO, 8L and 16L PDIP, 7L D2PAK and 5L TO-220.
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. 1/12/98
1
A
Company
CS8391
Electrical Characteristics: 6V VIN 26V, IOUT1 = IOUT2 = 100A, -40C TC 125uC, -40C TJ 150uC unless otherwise specified PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s Primary Output Stage (VOUT1) Output Voltage, VOUT1 Dropout Voltage Line Regulation Load Regulation Quiescent Current Ripple Rejection Current Limit Short Circuit Current Limit Reverse Current s Secondary Output (VOUT2) Output Voltage, VOUT2 Dropout Voltage Line Regulation Load Regulation Quiescent Current 100A IOUT2 100mA IOUT2 = 100mA IOUT2 = 100A 6V VIN 26V 100A IOUT2 100mA, VIN = 14V ENABLE = LOW, VIN = 12.8V ENABLE = HIGH, VIN = 16V, IOUT2 = 100mA f = 120Hz, IOUT2 = 50mA, 7V VIN 17V VOUT2 = 0V, VIN = 16V, IOUT1 = 0A VOUT2 = 5V, VIN = 0V 60 105 25 100 250 4.85 5.00 400 100 5 5 100 8 70 200 5.15 600 150 50 50 150 25 V mV mV mV mV A mA dB mA mA A VOUT1 = 0V, VIN = 16V VOUT1 = 5V, VIN = 0V 100A IOUT1 250mA IOUT1 = 250mA IOUT1 = 100A 6V VIN 26V 1mA IOUT1 250mA, VIN = 14V ENABLE = HIGH, VIN = 16V, IOUT1 = 250mA f = 120Hz, IOUT1 = 125mA, 7V VIN 17V 4.85 5.00 400 100 5 5 22 60 260 25 100 1500 70 400 5.15 600 150 50 50 50 V mV mV mV mV mA dB mA mA A
Ripple Rejection Current Limit Short Circuit Current Limit Reverse Current s Enable Function (ENABLE) Input Threshold Input Bias Current s Protection Circuits Overtemperature Threshold
ENABLE = LOW, 7V VIN 26V ENABLE = HIGH, 7V VIN 26V 0V VENABLE 5V
2.0 -2
1.2 1.2 0
0.8 2
V V A
(Guaranteed by Design)
150
180
C
2
CS8391
Package Lead Description
PACKAGE LEAD # LEAD SYMBOL FUNCTION
5 Lead D2PAK 1 2 3 4 5 VIN VOUT1 Gnd VOUT2 ENABLE Supply voltage to IC, usually direct from battery. 5V regulated output which is activated by ENABLE input. Ground connection. Standby output 5V, 100mA capability; always on. CMOS compatible input lead; switches VOUT1. When ENABLE is high, VOUT1 is active. Definition of Terms Current Limit Peak current that can be delivered to the output. Dropout Voltage The input-output voltage differential at which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has dropped 100mV from the nominal value obtained at 14V input, dropout voltage is dependent upon load current and junction temperature. Input Output Differential The voltage difference between the unregulated input voltage and the regulated output voltage for which the regulator will operate. Input Voltage The DC voltage applied to the input terminals with respect to ground. Line Regulation The change in output voltage for a change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected. Load Regulation The change in output voltage for a change in load current at constant chip temperature. Long Term Stability Output voltage stability under accelerated life-test conditions after 1000 hours with maximum rated voltage and junction temperature. Quiescent Current The part of the positive input current that does not contribute to the positive load current. i.e., the regulator ground lead current. Ripple Rejection The ratio of the peak-to-peak input ripple voltage to the peak-to-peak output ripple voltage. Short Circuit Current Limit Peak current that can be delivered by the output when forced to 0V. Temperature Stability of VOUT The percentage change in output voltage for a thermal variation from room temperature to either temperature extreme.
Typical Circuit Waveform
45V VIN 14V 31V 3V 26V 14V
ENABLE
2.0V 0.8V 5V 5V 2.4V 5V 0V 0V 5V 5V 5V 2.4V 0V 5V 5V 5V 5V 5V 0V 5V 5V 0V
VOUT1 VOUT2
System Condition
Turn On
Load Dump
Low VIN
Line Noise, Etc.
VOUT 1 Short Circuit
VOUT2 Short Circuit
Thermal Shutdown
Turn Off
3
CS8391
Application Notes
General
IOUT2(max) is the maximum output current for the application, and IQ is the quiescent current the regulator consumes at both IOUT1(max) and IOUT2(max). Once the value of PD(max) is known, the maximum permissible value of RQJA can be calculated: 150C - TA (2) PD 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. RQJA = In some cases, none of the packages will be sufficient to dissipate the heat generated by the IC, and an external heat sink will be required.
The CS8391 is a micropower dual 5V regulator. All bias required to operate the internal circuitry is derived from the standby output, VOUT2. If this output experiences an over current situation and collapses, then VOUT1 will also collapse (see timing diagrams). If there is critical circuitry that must remain active under most conditions it should be connected to VOUT2. Any circuitry that is likely to be subjected to a short circuit, e.g., circuitry outside the module, should be connected to VOUT1.
External Capacitors
Output capacitors are required for stability with the CS8391. Without them, the regulator outputs will oscillate. Actual size and type may vary depending upon the application load and temperature range. Capacitor effective series resistance (ESR) is also a factor in the IC stability. Worstcase is determined at the minimum ambient temperature and maximum load expected. Output capacitors can be increased in size to any desired value above the minimum. One possible purpose of this would be to maintain the output voltages during brief conditions of negative input transients that might be characteristic of a particular system. Capacitors must also be rated at all ambient temperatures expected in the system. To maintain regulator stability down to -40uC, capacitors rated at that temperature must be used. More information on capacitor selection for Smart Regulators is available in the Smart Regulator application note, Compensation for Linear Regulators.
IIN VIN
Smart Regulator
IOUT1 VOUT1 IOUT2 VOUT2
}
Control Features
IQ
Figure 1: Dual output regulator with key performance parameters labeled.
Heat Sinks
ENABLE
The ENABLE function controls VOUT1. When ENABLE is high, VOUT1 is on. When ENABLE is low, VOUT1 is off.
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 where: RQJC = the junctiontocase thermal resistance, RQCS = the casetoheat sink thermal resistance, and RQSA = the heat sinktoambient 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, heat sink and the interface between them. These values appear in heat sink data sheets of heat sink manufacturers. (3)
Calculating Power Dissipation in a Dual Output Linear Regulator
The maximum power dissipation for a dual output regulator (Figure 1) is: PD(max) = {VIN(max)VOUT1(min)}IOUT1(max)+ {VIN(max)VOUT2(min)}IOUT2(max)+VIN(max)IQ (1) where: VIN(max) is the maximum input voltage, VOUT1(min) is the minimum output voltage from VOUT1, VOUT2(min) is the minimum output voltage from VOUT2, IOUT1(max) is the maximum output current for the application,
4
CS8391
Test & Application Circuit
VIN
0.1mF
VOUT2
VCC C2
22mF ESR<8W
C1
VBATT
22mF ESR<8W
CS8391
VOUT1
mP
C3 ENABLE Gnd I/O Gnd
Load
* C1 required if regulator is located far from power supply filter. ** C2 and C3 required for stability. Capacitor must operate at minimum temperature expected during system operations.
5
CS8391
Package Specification
PACKAGE DIMENSIONS IN MM(INCHES) PACKAGE THERMAL DATA
Thermal Data 5 Lead D2 PAK RQJC typ 2.4 C/W RQJA typ 10-50* C/W * Depending on thermal properties of substrate. RQJA = RQJC + RQCA
5 Lead D2PAK (DP)
10.31 (.406) 10.05 (.396)
1.40 (.055) 1.14 (.045) 1.68 (.066) 1.40 (.055)
8.53 (.336) 8.28 (.326) 15.75 (.620) 14.73 (.580) 2.74(.108) 2.49(.098) 0.91 (.036) 0.66 (.026) 2.79 (.110) 2.29 (.090) 1.70 (.067) REF .254 (.010) REF
4.57 (.180) 4.31 (.170)
0.10 (.004) 0.00 (.000)
Ordering Information
Part Number CS8391YDP5 CS8391YDPR5
Rev. 1/12/98
Description 5 Lead D2PAK 5 Lead 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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