Datasheet CS8371ETVA7, CS8371ET7 Datasheet (Cherry Semiconductor)

1

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

Block Diagram

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 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 environ­ments. CherryÕs proprietary
NoCapª 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.

1 ENABLE

1

2 ENABLE

2

3V

OUT2

4 Gnd
5 Sense
6V

CC

7V

OUT1

Rev. 6/9/99

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: [phone] Fax: [phone]

Email: [e-mail]

Web Site: www.cherry-semi.com

A Company

¨

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

Pre-Regulator/
Bias Generator

Trimmed Bandgap
Voltage Reference

Thermal

Shutdown

ENABLE

ENABLE

V

Gnd

CC

1

2

-

+

1.2V

-

+

1.2V

Overvoltage

Shutdown

Current Limit

+

VIA

-

-

+

Current Limit

V

OUT1

Sense

V

OUT2

1

2

CS8371

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Electrical Characteristics: -40¡C ² TA² +85¡C, 10.5V ² VCC² 16.0V, ENABLE1= ENABLE2= 5.0V,

I

OUT1

= I

OUT2

= 5.0mA, unless otherwise stated.

■ Primary Output (V

OUT1

)

Output Voltage I

OUT1

= 1.0A 7.60 8.00 8.40 V
Line Regulation 10.5V ² VCC² 26V 50 mV
Load Regulation 5mA ² I

OUT1

² 1.0A 150 mV

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

Current

Quiescent Current VCC= 14V, I

OUT1

= 1.0A, I

OUT2

= 250mA 30 mA

Dropout Voltage I

OUT1

= 250mA 1.2 V
Dropout Voltage I

OUT1

= 1.0A 1.5 V
Quiescent Bias Current I

OUT1

= 5mA, ENABLE2= 0V, VCC= 14V 10 mA

IQ= ICC- I

OUT1

Quiescent Bias Current I

OUT1

= 1.0A, ENABLE2= 0V, VCC= 14V 22 mA

IQ= ICC- I

OUT1

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

C

OUT

= 0µF

f = 10kHz, VCC= 14V with 1.0VPPAC, 74 dB
C

OUT

= 0µF

f = 20kHz, VCC= 14V with 1.0VPPAC, 68 dB
C

OUT

= 0µF
Current Limit VCC= 16V 1.1 2.5 A
Overshoot Voltage 5mA ² I

REG1

² 1.0A 6.0 V

Output Noise 10Hz-100kHz 300 µV

rms

■ Secondary Output (V

OUT2

)

Output Voltage I

OUT2

= 250mA 4.75 5.00 5.25 V
Line Regulation 7V ² VCC² 26V 40 mV
Load Regulation 5mA ² I

OUT2

² 250mA 100 mV

Dropout Voltage I

OUT2

= 5.0mA 2.2 V
Dropout Voltage I

OUT2

= 250mA 2.5 V
Quiescent Bias Current I

OUT2

= 5mA, ENABLE1= 0V, VCC= 14V 7 mA

IQ= ICC- I

OUT2

Quiescent Bias Current I

OUT2

= 250mA, ENABLE1= 0V, VCC= 14V 8 mA

IQ= ICC- I

OUT2

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

C

OUT

= 0µF

f= 10kHz, VCC= 14V with 1.0VPPAC, 75 dB
C

OUT

= 0µF

f = 20kHz, VCC= 14V with 1.0VPPAC, 67 dB
C

OUT

= 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 V

CC

) ...........................................................................................................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

3

Electrical Characteristics: -40¡C ² TA² +85¡C, 10.5V ² VCC² 16.0V, ENABLE1= ENABLE2= 5.0V,

I

OUT1

= I

OUT2

= 5.0mA, unless otherwise stated.

CS8371

Package Pin Description

PACKAGE PIN # PIN SYMBOL FUNCTION

7 Lead TO-220

1 ENABLE

1

ENABLE control for the 8V, 1A output

2 ENABLE

2

ENABLE control for the 5V, 250mA output

3V

OUT2

5V ±5%, 250mA regulated output
4 Gnd Ground
5 Sense Sense feedback for the primary 8V output
6V

CC

Supply voltage, usually from battery
7V

OUT1

8V ±5%, 1A regulated output

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

■ Secondary Output (V

OUT2

): continued

Current Limit VCC= 16V 270 600 mA
Overshoot Voltage 5mA ² I

REG2

² 250mA 4.3 V

Output Noise 10Hz-100kHz 170 µV

rms

■ 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

Regulator 1 Output Voltage Regulator 2 Output Voltage

Regulator 1 Dropout Voltage

8.05
VIN = 14V

8.04

= 1A

I

OUT

8.03

8.02

8.01

8.00

7.99

Output Voltage (V)

7.98

7.97

7.96

7.95

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

Ambient Temperature (°C)

5.00

4.95

Output Voltage (V)

4.90

4.85

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

VIN = 14V

= 250A

I

OUT

Ambient Temperature (°C)

2.0

1.8

1.6

1.4

1.2

-40°C

1.0

0.8

Dropout Voltage (V)

0.6

0.4

0.2

0

25°C

85°C

0 100 200 300 400 500 600 700 800 900

Output Current (mA)

1000

4

CS8371

Typical Performance Characteristics: continued

Regulator 2 Dropout Voltage Regulator 1 Current Limit

Regulator 2 Current Limit

Quiescent Current Quiescent Current

Regulator 1 Quiescent Current

Regulator 2 Quiescent Current Regulator 1 Load Regulation

0

Regulator 2 Load Regulation

Regulator 1 Startup Regulator 2 Startup

Regulator 1 Line Transient Response

Dropout Voltage (V)

2.5

2.0

-40°C

1.5

25°C

85°C

1.0

0.5

0

0 50 100 150 200

Output Current (mA)

250

10

VIN = 14V

9

= 25°C

T

A

8

7

6

5

4

Reg 1 Output Voltage (V)

3

2

1

0

012

Reg 1 Output Current (A)

3

10

VIN = 14V

9

= 25°C

T

A

8

7

6

5

4

Reg 2 Output Voltage (V)

3

2

1

0

0 100 200

Reg 2 Output Current (mA)

300

400 500

9.0
Enable 1 = 5V
Enable 2 = 5V

8.5
V

= 14V

IN

8.0

1 = 1A

I

OUT

2 = 250mA

I

OUT

7.5

7.0

6.5

6.0

5.5

Quiescent Current (mA)

5.0

4.5

4.0

-40 -200 2040 6080

Ambient Temperature (°C)

1.0
Enable 1 = 0V
Enable 2 = 0V

0.9

= 14V

V

IN

0.8

0.7

0.6

0.5

0.4

0.3

Quiescent Current (mA)

0.2

0.1

0

-40 -200 2040 6080

Ambient Temperature (°C)

4.0
Enable 1 = 0V

Enable 2 = 5V

3.8

3.6

3.4

3.2

3.0

2.8

2.6

Quiescent Current (mA)

2.4

2.2

2.0

= 14V

V

IN

I

= 250mA

OUT

I

= 5mA

OUT

-40 -200 2040 6080

Ambient Temperature (°C)

8.020

VIN = 14V

8.015

8.010

8.005

8.000

7.995

Output Voltage (V)

7.990

7.985

7.980

25°C

0 100 200 300 400 500 600 700 800 900

Output Current (mA)

-40°C

85°C

6.0
Enable 1 = 5V

Enable 2 = 0V
V

= 14V

IN

5.5

5.0

4.5

I

= 5mA

OUT

4.0

Quiescent Current (mA)

3.5

3.0

-40 -200 2040 6080

Ambient Temperature (°C)

5.02
VIN = 14V

5.01

5.00

4.99

4.98

4.97

Output Voltage (V)

4.96

-40°C

4.95

4.94

100

0 50 100 150 200

Output Current (mA)

85°C

25°C

I

= 1A

OUT

250

C

8

T

7

I

OUT

6
5
4
3
2

1
0

Reg 1 Output Voltage (V)

5
4
3
2
1

Enable 1 (V)

0

01

= 0mF

OUT

= 25°C

A

= 5mA

23456789101112

Time (ms)

C

8

T

7

I

6

OUT

5
4
3
2
1
0

Reg 2 Output Voltage (V)

5
4
3
2
1

Enable 2 (V)

0

01

= 0mF

OUT

= 25°C

A

= 5mA

23456789101112

Time (ms)

C

= 0mF

OUT

T

= 25°C

A

2

1

0

-1

-2

Output Voltage Deviation (V)

16

14

12

10

Input Voltage (V)

0 100 200 300 400 500

Time (ns)

600

5

Typical Performance Characteristics: continued

CS8371

C

Regulator 2 Line Transient Response Regulator 1 Load Transient Response

Regulator 2 Load Transient Response

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 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 V

OUT

: The percentage change in out-

put voltage for a thermal variation from room temper­ature to either temperature extreme.

= 0mF

OUT

0.6
T

= 25°C

A

0.4

0.2

0

-0.2

-0.4

-0.6

Output Voltage Deviation (V)

16

14

12

10

Input Voltage (V)

0 100 200 300 400 500

Time (ns)

VIN = 14V

3

= 0mF

C

OUT

= 25°C

T

2

A

1

0

-1

-2

-3

Output Voltage Deviation (V)

1000

5

Load Current (mA)

600

0 5 10 15 20 25

Time (ms)

30

VIN = 14V

= 0mF

C

OUT

= 25°C

T

A

+500

0

-500

Output Voltage Deviation (mV)

250

5

0 5 10 15 20 25

Load Current (mA)

Time (ms)

30

TA = 25°C

= 14V

V

IN

= 0mF

C

OUT

100

80

60

Ripple Rejection (dB)

40

20

1 10 100 1k 10k 100k

Frequency (Hz)

1M

TA = 25°C

= 14V

V

IN

= 0mF

C

OUT

100

80

60

Ripple Rejection (dB)

40

20

1 10 100 1k 10k 100k

Frequency (Hz)

5

TA = 25°C
V

= 14V

IN

£ 1.6W

R

ESR

= 5ma to 1A

I

OUT

1

Unstable

Output Capacitor ESR (W)

1M

0.1
.01 0.1 1 10 100 1000

Region

Output Capacitor Size (mF)

6

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 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 NoCapª. 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.

Applications Circuit

Application Notes

CS8371

C1*

0.1 mF

ENABLE

1

V

IN

V

OUT1

Gnd

V

OUT2

8V

5V

Control

DISPLAY

Tuner IC

ENABLE

2

CS8371

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

7

Applications Notes: continued

CS8371

Calculating Power Dissipation

in a Dual Output Linear Regulator

The maximum power dissipation for a dual output regu­lator (Figure 1) is

P

D(max)

= {V

IN(max)

Ð V

OUT1(min)}IOUT1(max)

+

{V

IN(max)

Ð V

OUT2(min)}IOUT2(max)

+ V

IN(max)IQ

, (1)

where

V

IN(max)

is the maximum input voltage,

V

OUT1(min)

is the minimum output voltage from V

OUT

1

,

V

OUT2(min)

is the minimum output voltage from V

OUT

2

,

I

OUT1(max)

is the maximum output current, for the appli-

cation,

I

OUT2(max)

is the maximum output current, for the appli-

cation,

IQis the quiescent current the regulator consumes at
I

OUT(max)

.

Once the value of P

D(max)

is known, the maximum permis-

sible value of RQJAcan be calculated:

RQJA=

(2)

The value of RQJAcan 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:

RQ

JA

= RQJC+ RQCS+ RQSA, (3)

where

RQJC= the junctionÐtoÐcase thermal resistance,
RQCS= the caseÐtoÐheatsink thermal resistance, and
RQSA= the heatsinkÐtoÐambient thermal resistance.

RQ

JC

appears in the package section of the data sheet. Like

RQJA, it too is a function of package type. RQCSand RQ

SA

are functions of the package type, heatsink and the inter­face between them. These values appear in heatsink data
sheets of heatsink manufacturers.

150¡C - T

A

P

D

Figure 1: Dual output regulator with key performance parameters
labeled.

I

V

IN

IN

Smart

Regulator

Control
Features

}

I

Q

I

OUT1

I

OUT2

V

V

OUT1

OUT2

8

Rev. 6/9/99

© 1999 Cherry Semiconductor Corporation

CS8371

Part Number Description

CS8371ET7 7 Lead TO-220 Straight
CS8371ETVA7 7 Lead TO-220 Vertical

Thermal Data TO-220

RQ

JC

typ 2.4 ûC/W

RQ

JA

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)