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CS8371
CS8371
8V/1A, 5V/250mA Dual Regulator with Independent Output Enables and NoCap
Description
The CS8371 is a 8V/5V dual output linear regulator. The 8V 5% output sources 1A, while the 5V 5% output sources 250mA. Each output is controlled by its own ENABLE lead. Setting the ENABLE input high turns on the associated regulator output. Holding both ENABLE inputs low puts the IC into sleep mode where current consumption is less than 10A. The regulator is protected against overvoltage, short-circuit and thermal runaway conditions. The device can withstand 45V load dump transients making suitable for use in automotive environments. CherryOs proprietary NoCap solution is the first technology which allows the output to be stable without the use of an external capacitor. The CS8371 is available in a 7 lead TO-220 package with copper tab. The tab can be connected to a heatsink if necessary.
Features
s Two Regulated Outputs 8V 5%, 1A 5V 5%, 250mA s Independent ENABLE for each Output s Separate Sense Feedback Lead for 8V Output s <10A Sleep Mode Current s Fault Protection Overvoltage Shutdown +45V Peak Transient Voltage Short Circuit Thermal Shutdown s CMOS Compatible, LowCurrent ENABLE Inputs
Block Diagram
VCC Overvoltage Shutdown ENABLE1
Current Limit +
VOUT1
Package Options
TO-220 7 Lead
Tab (Gnd)
1.2V
Trimmed Bandgap Voltage Reference
Thermal Shutdown
+ -
ENABLE2
Gnd
NoCap is a trademark of Cherry Semiconductor Corporation, and is patented.
Rev. 6/9/99
+
-
1.2V
-
+
Pre-Regulator/ Bias Generator
Sense VIA
VOUT2
Current Limit
1
1 ENABLE 1 2 ENABLE 2 3 VOUT2 4 Gnd 5 Sense 6 VCC 7 VOUT1
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
1
A
Company
CS8371
Absolute Maximum Ratings Power Dissipation .............................................................................................................................................Internally Limited ENABLE Input Voltage Range .............................................................................................................................-0.6V to +10.0V Load Current (8V Regulator)...........................................................................................................................Internally Limited Load Current (5V Regulator)...........................................................................................................................Internally Limited Transient Peak Voltage (31V load dump @ 14V VCC) ...........................................................................................................45V Storage Temperature Range ................................................................................................................................-65C to +150C Junction Temperature Range...............................................................................................................................-40C to +150C Lead Temperature Soldering: Wave Solder (through hole styles only) ..........................................10 sec. max, 260C peak Electrical Characteristics: -40C TA +85C, 10.5V VCC 16.0V, ENABLE 1 = ENABLE 2 = 5.0V, IOUT1 = IOUT2 = 5.0mA, unless otherwise stated.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s Primary Output (VOUT1) Output Voltage Line Regulation Load Regulation Sleep Mode Quiescent Current Quiescent Current Dropout Voltage Dropout Voltage Quiescent Bias Current Quiescent Bias Current Ripple Rejection IOUT1 = 1.0A 10.5V VCC 26V 5mA IOUT1 1.0A VCC = 14V, ENABLE 1 = ENABLE 2 = 0V VCC = 14V, IOUT1 = 1.0A, IOUT2 = 250mA IOUT1 = 250mA IOUT1 = 1.0A IOUT1 = 5mA, ENABLE2 = 0V, VCC = 14V IQ = ICC - IOUT1 IOUT1 = 1.0A, ENABLE2 = 0V, VCC = 14V IQ = ICC - IOUT1 f = 120Hz, VCC = 14V with 1.0VPP AC, COUT = 0F f = 10kHz, VCC = 14V with 1.0VPP AC, COUT = 0F f = 20kHz, VCC = 14V with 1.0VPP AC, COUT = 0F VCC = 16V 5mA IREG1 1.0A 10Hz-100kHz 300 1.1 90 74 68 2.5 6.0 0 0.2 7.60 8.00 8.40 50 150 10.0 30 1.2 1.5 10 22 V mV mV A mA V V mA mA dB dB dB A V Vrms
Current Limit Overshoot Voltage Output Noise s Secondary Output (VOUT2) Output Voltage Line Regulation Load Regulation Dropout Voltage Dropout Voltage Quiescent Bias Current Quiescent Bias Current Ripple Rejection
IOUT2 = 250mA 7V VCC 26V 5mA IOUT2 250mA IOUT2 = 5.0mA IOUT2 = 250mA IOUT2 = 5mA, ENABLE1 = 0V, VCC = 14V IQ = ICC - IOUT2 IOUT2 = 250mA, ENABLE1 = 0V, VCC = 14V IQ = ICC - IOUT2 f = 120Hz, VCC = 14V with 1.0 VPP AC, COUT = 0F f= 10kHz, VCC = 14V with 1.0VPP AC, COUT = 0F f = 20kHz, VCC = 14V with 1.0VPP AC, COUT = 0F 2
4.75
5.00
5.25 40 100 2.2 2.5 7 8
V mV mV V V mA mA dB dB dB
90 75 67
CS8371
Electrical Characteristics: -40C TA +85C, 10.5V VCC 16.0V, ENABLE 1 = ENABLE 2 = 5.0V, IOUT1 = IOUT2 = 5.0mA, unless otherwise stated.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s Secondary Output (VOUT2): continued Current Limit VCC = 16V Overshoot Voltage Output Noise 5mA IREG2 250mA 10Hz-100kHz
270 170
600 4.3
mA V Vrms
s ENABLE Function (ENABLE) Input Current VCC = 14V, 0V ENABLE 5.5V Input Voltage Low High
-150 0 2.0
150 0.8 5.0
A V V
s Protection Circuitry ESD Threshold Overvoltage Shutdown Thermal Shutdown Thermal Hysteresis
Human Body Model Guaranteed by Design
2.0 24 150
4.0 30 180 30
kV V C C
Package Pin Description
PACKAGE PIN # PIN SYMBOL FUNCTION
7 Lead TO-220 1 2 3 4 5 6 7
ENABLE1 ENABLE 2 VOUT2 Gnd Sense VCC VOUT1
ENABLE control for the 8V, 1A output ENABLE control for the 5V, 250mA output 5V 5%, 250mA regulated output Ground Sense feedback for the primary 8V output Supply voltage, usually from battery 8V 5%, 1A regulated output
Typical Performance Characteristics
8.05 8.04 8.03 8.02 8.01 8.00 7.99 7.98 7.97 7.96 7.95 -40 -20 0 20 40 60 80 100 120 140 4.85 -40 -20 0 20 40 60 80 100 120 140 VIN = 14V IOUT = 1A 5.00 VIN = 14V IOUT = 250A 2.0 1.8 1.6
Dropout Voltage (V)
Output Voltage (V)
Output Voltage (V)
1.4 1.2 1.0 0.8
4.95
-40C
25C
4.90
85C
0.6 0.4 0.2 0 0 100 200 300 400 500 600 700 800 900 1000
Ambient Temperature (C)
Ambient Temperature (C)
Output Current (mA)
Regulator 1 Output Voltage
Regulator 2 Output Voltage
Regulator 1 Dropout Voltage
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CS8371
Typical Performance Characteristics: continued
2.5
10 9 VIN = 14V TA = 25C
10 9 VIN = 14V TA = 25C
Reg 1 Output Voltage (V)
2.0
Dropout Voltage (V)
-40C 25C
8 7 6 5 4 3 2 1
Reg 2 Output Voltage (V)
1 2 3
8 7 6 5 4 3 2 1 0 0 100 200 300 400 500
1.5
85C
1.0
0.5
0
0
50
100
150
200
250
00
Output Current (mA)
Reg 1 Output Current (A)
Reg 2 Output Current (mA)
Regulator 2 Dropout Voltage
Regulator 1 Current Limit
Regulator 2 Current Limit
9.0 8.5 Enable 1 = 5V Enable 2 = 5V VIN = 14V IOUT 1 = 1A IOUT 2 = 250mA
1.0 0.9 0.8 Enable 1 = 0V Enable 2 = 0V VIN = 14V
6.0 Enable 1 = 5V Enable 2 = 0V VIN = 14V
Quiescent Current (mA)
8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 -40
5.5
Quiescent Current (mA)
0.7 0.6 0.5 0.4 0.3 0.2 0.1
Quiescent Current (mA)
5.0
4.5
4.0
IOUT = 5mA
IOUT = 1A
3.5
-20
0
20
40
60
80
0 -40
-20
0
20
40
60
80
Ambient Temperature (C)
Ambient Temperature (C)
3.0 -40
-20
0
20
40
60
80
Ambient Temperature (C)
Quiescent Current
Quiescent Current
Regulator 1 Quiescent Current
4.0 3.8 3.6 Enable 1 = 0V Enable 2 = 5V VIN = 14V
8.020 VIN = 14V 8.015 8.010
5.02 VIN = 14V 5.01 5.00
Quiescent Current (mA)
25C 85C
Output Voltage (V)
IOUT = 250mA IOUT = 5mA
Output Voltage (V)
3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 -40 -20 0
8.005 8.000
4.99 4.98 4.97 4.96 4.95 4.94
25C
7.995 7.990 7.985 7.980
-40C 85C
-40C
20
40
60
80
0
100
200
300
400
500
600
700
800
900 1000
0
50
100
150
200
250
Ambient Temperature (C)
Output Current (mA)
Output Current (mA)
Regulator 2 Quiescent Current
Regulator 1 Load Regulation
Regulator 2 Load Regulation
8 7 6 5 4 3 2 1 0
COUT = 0mF TA = 25C IOUT = 5mA
8 7 6 5 4 3 2 1 0
COUT = 0mF TA = 25C IOUT = 5mA
Output Voltage Deviation (V)
Reg 1 Output Voltage (V)
Reg 2 Output Voltage (V)
2 1 0 -1 -2
COUT = 0mF TA = 25C
Input Voltage (V)
5 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12
5 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12
Enable 1 (V)
Enable 2 (V)
16 14 12 10 0 100 200 300 400 500 600
Time (ms)
Time (ms)
Time (ns)
Regulator 1 Startup
Regulator 2 Startup
Regulator 1 Line Transient Response
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CS8371
Typical Performance Characteristics: continued
0.6 0.4 0.2 0 -0.2 -0.4 -0.6
COUT = 0mF TA = 25C
3 2 1 0 -1 -2 -3
VIN = 14V COUT = 0mF TA = 25C
Load Current (mA) Output Voltage Deviation (mV)
Load Current (mA) Output Voltage Deviation (V)
Output Voltage Deviation (V)
VIN = 14V COUT = 0mF TA = 25C +500 0 -500
Input Voltage (V)
16 14 12 10 0 100 200 300 400 500 600
1000
250
5 0 5 10 15 20 25 30
5 0 5 10 15 20 25 30
Time (ns)
Time (ms)
Time (ms)
Regulator 2 Line Transient Response
Regulator 1 Load Transient Response
Regulator 2 Load Transient Response
TA = 25C VIN = 14V COUT = 0mF 100 100
5 TA = 25C VIN = 14V COUT = 0mF TA = 25C VIN = 14V RESR 1.6W IOUT = 5ma to 1A
80
80
Output Capacitor ESR (W)
Ripple Rejection (dB)
Ripple Rejection (dB)
1
60
60
Unstable Region
40
40
20
1
10
100
1k
10k
100k
1M
20
1
10
100
1k
10k
100k
1M
0.1
.01
0.1
1
10
100
1000
Frequency (Hz)
Frequency (Hz)
Output Capacitor Size (mF)
Regulator 1 Ripple Rejection
Regulator 2 Ripple Rejection
Regulator 1 Stability
Definition of Terms
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. Current Limit: Peak current that can be delivered to the output. Input Voltage: The DC voltage applied to the input terminals with respect to ground. Input Output Differential: The voltage difference between the unregulated input voltage and the regulated output voltage for which the regulator will operate. 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. Output Noise Voltage: The rms AC voltage at the output, with constant load and no input ripple, measured over a specified frequency range. Quiescent Current: The part of the positive input current that does not contribute to the positive load current. 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. Temperature Stability of VOUT: The percentage change in output voltage for a thermal variation from room temperature to either temperature extreme.
5
CS8371
Applications Circuit
C 1* 0.1 mF
DISPLAY VIN VOUT1 8V
CS8371
Control ENABLE1
ENABLE2 Gnd
VOUT2
5V
Tuner IC
*C1 is required if regulator is far from power source filter.
Application Notes With separate control of each output channel, the CS8371 is ideal for applications where each load must be switched independently. In an automotive radio, the 8V output drives the displays and tape drive motors while the 5V output supplies the Tuner IC and memory. over temperature, load and line variations without the need for an expensive external capacitor. It incorporates high gain (>80dB) and large unity gain bandwidth (>100kHz) while maintaining many of the characteristics of a single-pole amplifier (large phase margin and no overshoot). NoCap is ideally suited for slow switching or steady loads. If the load displays large transient current requirements, such as with high frequency microprocessors, an output storage capacitor may be needed. Some large capacitor and small capacitor ESR values at the output may cause small signal oscillations at the output. This will depend on the load conditions. With these types of loads, a traditional output stage may be better suited for proper operation. Output 1 employs NoCap. Refer to the plots in the Typical Performance Characteristics section for appropriate output capacitor selections for stability if an external capacitor is required by the switching characteristics of the load. Output 2 has a Darlington NPN-type output structure and is inherently stable with any type of capacitive load or no capacitor at all.
Stability Considerations/NoCap Normally a low dropout or quasi-low dropout regulator (or any type requiring a slow lateral PNP in the control loop) necessitates a large external compensation capacitor at the output of the IC. The external capacitor is also used to curtail overshoot, determine startup delay time and load transient response. Traditional LDO regulators typically have low unity gain bandwidth, display overshoot and poor ripple rejection. Compensation is also an issue because the high frequency load capacitor value, ESR (Equivalent Series Resistance) and board layout parasitics all can create oscillations if not properly accounted for. NoCap is a Cherry Semiconductor exclusive output stage which internally compensates the LDO regulator
6
CS8371
Applications Notes: continued 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, 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, IOUT2(max) is the maximum output current, for the application, IQ is the quiescent current the regulator consumes at IOUT(max). Once the value of P D(max) is known, the maximum permissible value of RQJA can be calculated: RQJA = 150C - TA PD (2)
Figure 1: Dual output regulator with key performance parameters labeled.
IIN VIN
Smart Regulator
IOUT1 VOUT1 IOUT2 VOUT2
(1)
}
Control Features
IQ
Heatsinks A heatsink 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 heatsink data sheets of heatsink manufacturers.
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.
7
CS8371
Package Specification
PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA
Thermal Data RQJC typ RQJA typ
7 Lead TO-220 (T) Straight
TO-220 2.4 50
uC/W uC/W
7 Lead TO-220 (TVA) Vertical
4.83 (.190) 4.06 (.160) 1.40 (.055) 1.14 (.045)
2.87 (.113) 2.62 (.103)
10.54 (.415) 9.78 (.385)
10.54 (.415) 9.78 (.385) 2.87 (.113) 2.62 (.103)
3.96 (.156) 3.71 (.146)
1.40 (.055) 1.14 (.045)
6.55 (.258) 5.94 (.234)
3.96 (.156) 3.71 (.146)
14.99 (.590) 14.22 (.560)
6.55 (.258) 5.94 (.234)
14.99 (.590) 14.22 (.560)
11.86 (.467) 2.03 (.080) 2.92 (.115) 2.92 (.115) 2.29 (.090)
14.22 (.560) 13.72 (.540)
8.26 (.325)
0.81 (.030)
0.94 (.037) 0.58 (.023)
7.62 (.300)
0.56 (.022) 0.36 (.014) 1.27 (.050) TYP
4.34 (.171) 7.52 (.296)
1.40 (.055) 1.14 (.045) 7.75 (.305) 7.49 (.295)
0.64 (.025) 0.38 (.015)
0.56 (.022) 0.36 (.014)
4.83 (.190) 4.06 (.160)
2.92 (.115) 2.29 (.090)
Ordering Information
Part Number CS8371ET7 CS8371ETVA7
Description 7 Lead TO-220 Straight 7 Lead TO-220 Vertical
Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information.
Rev. 6/9/99
8
(c) 1999 Cherry Semiconductor Corporation

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