CS8371ETVA7 - Cherry Semiconductor

Features

■Two Regulated Outputs

8V ±5%, 1A

5V ±5%, 250mA

■Independent ENABLE for

each Output

■Separate Sense Feedback

Lead for 8V Output

■<10µA Sleep Mode Current

■Fault Protection

Overvoltage Shutdown

+45V Peak Transient

Voltage

Short Circuit

Thermal Shutdown

■CMOS Compatible, Low-

Current ENABLE Inputs

Package Options

TO-220 7 Lead

Tab (Gnd)

CS8371

8V/1A, 5V/250mA Dual Regulator with

Independent Output Enables and NoCapª

CS8371

Description

Pre-Regulator/

Bias Generator

Thermal

Shutdown

Trimmed Bandgap

Voltage Reference

ENABLE1

VCC

ENABLE2

Gnd

VOUT2

Sense

VOUT1

Overvoltage

Shutdown

Current Limit

VIA

Current Limit

1.2V

Block Diagram

The CS8371 is a 8V/5V dual output

linear regulator. The 8V ±5% output

sources 1A, while the 5V ±5% out-

put sources 250mA. Each output is

controlled by its own ENABLE

lead. Setting the ENABLE input

high turns on the associated regula-

tor output. Holding both ENABLE

inputs low puts the IC into sleep

mode where current consumption

is less than 10µA.

The regulator is protected against

overvoltage, short-circuit and ther-

mal runaway conditions. The

device can withstand 45V load

dump transients making suitable

for use in automotive environ-

ments. CherryÕs proprietary

NoCapª solution is the first tech-

nology 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.

1 ENABLE1

2 ENABLE2

OUT2

4 Gnd

5 Sense

OUT1

Rev. 6/9/99

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

A Company

NoCap is a trademark of Cherry Semiconductor Corporation, and is patented.

CS8371

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Electrical Characteristics: -40¡C ² TA² +85¡C, 10.5V ² VCC ² 16.0V, ENABLE1= ENABLE2= 5.0V,

IOUT1 = IOUT2 = 5.0mA, unless otherwise stated.

■Primary Output (VOUT1)

Output Voltage IOUT1 = 1.0A 7.60 8.00 8.40 V

Line Regulation 10.5V ² VCC ² 26V 50 mV

Load Regulation 5mA ² IOUT1 ² 1.0A 150 mV

Sleep Mode Quiescent VCC = 14V, ENABLE1= ENABLE2= 0V 0 0.2 10.0 µA

Current

Quiescent Current VCC = 14V, IOUT1 = 1.0A, IOUT2 = 250mA 30 mA

Dropout Voltage IOUT1 = 250mA 1.2 V

Dropout Voltage IOUT1 = 1.0A 1.5 V

Quiescent Bias Current IOUT1 = 5mA, ENABLE2= 0V, VCC = 14V 10 mA

IQ= ICC - IOUT1

Quiescent Bias Current IOUT1 = 1.0A, ENABLE2= 0V, VCC = 14V 22 mA

IQ= ICC - IOUT1

Ripple Rejection f = 120Hz, VCC = 14V with 1.0VPP AC, 90 dB

COUT = 0µF

f = 10kHz, VCC = 14V with 1.0VPP AC, 74 dB

COUT = 0µF

f = 20kHz, VCC = 14V with 1.0VPP AC, 68 dB

COUT = 0µF

Current Limit VCC = 16V 1.1 2.5 A

Overshoot Voltage 5mA ² IREG1 ² 1.0A 6.0 V

Output Noise 10Hz-100kHz 300 µVrms

■Secondary Output (VOUT2)

Output Voltage IOUT2 = 250mA 4.75 5.00 5.25 V

Line Regulation 7V ² VCC ² 26V 40 mV

Load Regulation 5mA ² IOUT2 ² 250mA 100 mV

Dropout Voltage IOUT2 = 5.0mA 2.2 V

Dropout Voltage IOUT2 = 250mA 2.5 V

Quiescent Bias Current IOUT2 = 5mA, ENABLE1= 0V, VCC = 14V 7 mA

IQ= ICC - IOUT2

Quiescent Bias Current IOUT2 = 250mA, ENABLE1= 0V, VCC = 14V 8 mA

IQ= ICC - IOUT2

Ripple Rejection f = 120Hz, VCC = 14V with 1.0 VPP AC, 90 dB

COUT = 0µF

f= 10kHz, VCC = 14V with 1.0VPP AC, 75 dB

COUT = 0µF

f = 20kHz, VCC = 14V with 1.0VPP AC, 67 dB

COUT = 0µF

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 ................................................................................................................................-65¡C to +150¡C

Junction Temperature Range...............................................................................................................................-40¡C to +150¡C

Lead Temperature Soldering: Wave Solder (through hole styles only)..........................................10 sec. max, 260¡C peak

Electrical Characteristics: -40¡C ² TA² +85¡C, 10.5V ² VCC ² 16.0V, ENABLE1= ENABLE2= 5.0V,

IOUT1 = IOUT2 = 5.0mA, unless otherwise stated.

CS8371

Package Pin Description

PACKAGE PIN # PIN SYMBOL FUNCTION

7 Lead TO-220

1 ENABLE1ENABLE control for the 8V, 1A output

2 ENABLE2ENABLE control for the 5V, 250mA output

OUT2 5V ±5%, 250mA regulated output

4 Gnd Ground

5 Sense Sense feedback for the primary 8V output

CC Supply voltage, usually from battery

OUT1 8V ±5%, 1A regulated output

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

■Secondary Output (VOUT2): continued

Current Limit VCC = 16V 270 600 mA

Overshoot Voltage 5mA ² IREG2 ² 250mA 4.3 V

Output Noise 10Hz-100kHz 170 µVrms

■ENABLE Function (ENABLE)

Input Current VCC = 14V, 0V ² ENABLE ² 5.5V -150 150 µA

Input Voltage Low 0 0.8 V

High 2.0 5.0 V

■Protection Circuitry

ESD Threshold Human Body Model ±2.0 ±4.0 kV

Overvoltage Shutdown 24 30 V

Thermal Shutdown Guaranteed by Design 150 180 ¡C

Thermal Hysteresis 30 ¡C

Typical Performance Characteristics

Output Voltage (V)

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

Ambient Temperature (°C)

VIN = 14V

IOUT = 1A

Regulator 1 Output Voltage Regulator 2 Output Voltage

Output Voltage (V)

-40 -20 0 20 40 60 80 100 120 140

Ambient Temperature (°C)

5.00

4.95

4.90

4.85

VIN = 14V

IOUT = 250A

Dropout Voltage (V)

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

00 100 200 300 400 500 600 700 800 900

Output Current (mA)

1000

-40°C 25°C

85°C

Regulator 1 Dropout Voltage

CS8371

Typical Performance Characteristics: continued

Dropout Voltage (V)

2.5

2.0

1.5

1.0

0.5

00 50 100 150 200

Output Current (mA)

250

-40°C

25°C

85°C

Regulator 2 Dropout Voltage Regulator 1 Current Limit

Reg 1 Output Voltage (V)

0012

Reg 1 Output Current (A)

VIN = 14V

TA = 25°C

Reg 2 Output Voltage (V)

00 100 200

Reg 2 Output Current (mA)

300

VIN = 14V

TA = 25°C

400 500

Regulator 2 Current Limit

Quiescent Current (mA)

9.0

8.5

8.0

7.5

7.0

6.5

6.0

5.5

5.0

4.5

4.0

-40 -200 20406080

Ambient Temperature (°C)

Enable 1 = 5V

Enable 2 = 5V

VIN = 14V

IOUT 1 = 1A

IOUT 2 = 250mA

Quiescent Current Quiescent Current

Quiescent Current (mA)

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

-40 -200 20406080

Ambient Temperature (°C)

Enable 1 = 0V

Enable 2 = 0V

VIN = 14V

Quiescent Current (mA)

6.0

5.5

5.0

4.5

4.0

3.5

3.0

-40 -200 20406080

Ambient Temperature (°C)

IOUT = 5mA

IOUT = 1A

Enable 1 = 5V

Enable 2 = 0V

VIN = 14V

Regulator 1 Quiescent Current

Quiescent Current (mA)

4.0

3.8

3.6

3.4

3.2

3.0

2.8

2.6

2.4

2.2

2.0

-40 -200 20406080

Ambient Temperature (°C)

IOUT = 5mA

IOUT = 250mA

Enable 1 = 0V

Enable 2 = 5V

VIN = 14V

Regulator 2 Quiescent Current Regulator 1 Load Regulation

Output Voltage (V)

8.020

8.015

8.010

8.005

8.000

7.995

7.990

7.985

7.980 0 100 200 300 400 500 600 700 800 900

Output Current (mA)

100

85°C

25°C -40°C

VIN = 14V

Output Voltage (V)

5.02

5.01

5.00

4.99

4.98

4.97

4.96

4.95

4.94 0 50 100 150 200

Output Current (mA)

250

-40°C

25°C

85°C

VIN = 14V

Regulator 2 Load Regulation

Enable 1 (V)

Time (ms)

23456789101112

Reg 1 Output Voltage (V)

COUT = 0mF

TA = 25°C

IOUT = 5mA

Regulator 1 Startup Regulator 2 Startup

Enable 2 (V)

Time (ms)

23456789101112

Reg 2 Output Voltage (V)

COUT = 0mF

TA = 25°C

IOUT = 5mA

Output Voltage Deviation (V)

-1

-2

0 100 200 300 400 500

Time (ns)

600

Input Voltage (V)

COUT = 0mF

TA = 25°C

Regulator 1 Line Transient Response

Typical Performance Characteristics: continued

CS8371

Output Voltage Deviation (V)

0.4

0.2

-0.2

-0.4

0 100 200 300 400 500

Time (ns)

600

Input Voltage (V)

-0.6

0.6 COUT = 0mF

TA = 25°C

Regulator 2 Line Transient Response Regulator 1 Load Transient Response

Output Voltage Deviation (V)

-1

-2

1000

0 5 10 15 20 25

Time (ms)

Load Current (mA)

-3

3VIN = 14V

COUT = 0mF

TA = 25°C

Output Voltage Deviation (mV)

+500

-500

250

0 5 10 15 20 25

Time (ms)

Load Current (mA)

VIN = 14V

COUT = 0mF

TA = 25°C

Regulator 2 Load Transient Response

Ripple Rejection (dB)

100

201 10 100 1k 10k 100k

Frequency (Hz)

TA = 25°C

VIN = 14V

COUT = 0mF

Regulator 1 Ripple Rejection Regulator 2 Ripple Rejection

Ripple Rejection (dB)

100

201 10 100 1k 10k 100k

Frequency (Hz)

TA = 25°C

VIN = 14V

COUT = 0mF

Output Capacitor ESR (W)

0.1 .01 0.1 1 10 100 1000

Output Capacitor Size (mF)

Unstable

Region

TA = 25°C

VIN = 14V

RESR £ 1.6W

IOUT = 5ma to 1A

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 tech-

niques 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 accelerat-

ed 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 out-

put voltage for a thermal variation from room temper-

ature to either temperature extreme.

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.

Stability Considerations/NoCapª

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.

NoCapª is a Cherry Semiconductor exclusive output

stage which internally compensates the LDO regulator

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).

NoCapª is ideally suited for slow switching or steady

loads. If the load displays large transient current require-

ments, 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 NoCapª. Refer to the plots in the

Typical Performance Characteristics section for appropri-

ate 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 struc-

ture and is inherently stable with any type of capacitive

load or no capacitor at all.

Applications Circuit

Application Notes

CS8371

C1*

0.1 mF

ENABLE1

VIN VOUT1

Gnd

VOUT2

Control

DISPLAY

Tuner IC

ENABLE2

CS8371

*C1is required if regulator is far from power source filter.

Applications Notes: continued

CS8371

Calculating Power Dissipation

in a Dual Output Linear Regulator

The maximum power dissipation for a dual output regu-

lator (Figure 1) is

PD(max) = {VIN(max) Ð VOUT1(min)}IOUT1(max) +

{VIN(max) Ð 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 appli-

cation,

IOUT2(max) is the maximum output current, for the appli-

cation,

IQis the quiescent current the regulator consumes at

IOUT(max).

Once the value of P

D(max) is known, the maximum permis-

sible value of RQJA can be calculated:

RQJA =(2)

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 150¡C.

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.

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 junctionÐtoÐcase thermal resistance,

RQCS = the caseÐtoÐheatsink thermal resistance, and

RQSA = the heatsinkÐtoÐambient 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 inter-

face between them. These values appear in heatsink data

sheets of heatsink manufacturers.

150¡C - TA

VIN

VOUT2

IIN

Control

Features

}

IOUT2

VOUT1

IOUT1

Smart

Regulator

Figure 1: Dual output regulator with key performance parameters

labeled.

CS8371

Part Number Description

CS8371ET7 7 Lead TO-220 Straight

CS8371ETVA7 7 Lead TO-220 Vertical

Thermal Data TO-220

RQJC typ 2.4 ûC/W

RQJA typ 50 ûC/W

Package Specification

PACKAGE THERMAL DATA

Ordering Information Cherry Semiconductor Corporation reserves the right to

make changes to the specifications without notice. Please

contact Cherry Semiconductor Corporation for the latest

available information.

PACKAGE DIMENSIONS IN mm (INCHES)

7 Lead TO-220 (T) Straight

2.87 (.113)

2.62 (.103)

9.78 (.385)

10.54 (.415)

1.40 (.055)

1.14 (.045)

0.64 (.025)

0.38 (.015)

0.56 (.022)

0.36 (.014)

1.40 (.055)

1.14 (.045)

4.83 (.190)

4.06 (.160)

14.22 (.560)

13.72 (.540)

0.94 (.037)

0.58 (.023)

7.75 (.305)

7.49 (.295) 2.92 (.115)

2.29 (.090)

3.71 (.146)

3.96 (.156) 14.99 (.590)

14.22 (.560)

6.55 (.258)

5.94 (.234)

7 Lead TO-220 (TVA) Vertical

10.54 (.415)

9.78 (.385)

2.03 (.080)

7.52 (.296)

4.34

(.171)

1.40 (.055)

1.14 (.045)

14.99 (.590)

14.22 (.560)

11.86 (.467)

4.83 (.190)

4.06 (.160)

8.26

(.325)

7.62 (.300)

0.81

(.030) 1.27

(.050)

TYP

0.56 (.022)

0.36 (.014)

2.92 (.115)

2.29 (.090)

2.87 (.113)

2.62 (.103)

6.55 (.258)

5.94 (.234)

2.92

(.115)

3.96 (.156)

3.71 (.146)