Datasheet CS8281YDPR5, CS8281YDP5 Datasheet (Cherry Semiconductor)

1

Features

■ 5V, 250mA Primary Output

■ 5V, 100mA Secondary

Output

■ 3% Tolerance, Both

Outputs

■ ON/OFF Control for

Primary Output

■ Low Quiescent Current

Drain (100µA V

OUT2

)

■ Low Reverse Current

■ Protection Features

Reverse Battery (-15V)
74V Load Dump
Short Circuit
Overtemperature
Overvoltage (34V)

Package Options

CS8281

5V/250mA, 5V/100mA Micropower

Low Dropout Regulator with ENABLE

CS8281

Description

Block Diagram

Absolute Maximum Ratings

Input Voltage.....................................................................................-15V to 74V

Power Dissipation.................................................................Internally Limited

Operating Temperature Range................................................-40¡C to +125¡C

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

Storage Temperature Range ....................................................-55¡C to +150¡C

Electrostatic Discharge (Human Body Model) ..........................................4kV

Lead Temperature Soldering

Reflow (SMD styles only)................16 sec. max above 183¡C, 230¡C peak

The CS8281 is a precision, dual 5V
micropower linear voltage regula­tor. The switched primary output
(V

OUT1

) supplies up to 250mA

while the secondary (V

OUT2

) is
capable of supplying 100mA. Both
outputs have a maximum dropout
voltage of 600mV and low reverse
current. Quiescent current drain is
typically 150µA when supplying
100µA from each output.

The ENABLE input provides logic
level control of the primary output.

With the primary output disabled,
quiescent current drain is typically
100µA when supplying 100µA from
the secondary output.

The CS8281 is extremely robust
with protection provided for
reverse battery, short circuit, over­voltage, and overtemperature on
both outputs.

The CS8281 is available in a 5-lead
D2PAK.

5 Lead D2PAK

Tab (Gnd)

1

Consult factory for 8L and 16L SO, 8L and
16L PDIP, 7L D

2

PAK and 5L TO-220.

1. V

IN

2. V

OUT1

3. Gnd

4. V

OUT2

5. ENABLE

A Company

¨

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: [phone] Fax: [phone]

Email: [e-mail]

Web Site: www.cherry-semi.com

Rev. 9/16/97

V

ENABLE

Pwr Gnd

IN

+

-

Bandgap

Reference

Thermal

Shutdown

+

-

Over

Voltage

Shutdown

+

-

Primary Output

Secondary Output

Current

Limit

Current

Limit

V

OUT

V

OUT

V

OUT

V

OUT

1

Sense

1

2

Sense

2

Gnd

2

CS8281

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Electrical Characteristics: 6V ² VIN² 26V, I

OUT1

= I

OUT2

= 100µA, -40¡C ² TC² 125ûC unless otherwise specified

■ Primary Output Stage (V

OUT1

)

Output Voltage, V

OUT1

100µA ² I

OUT1

² 250mA 4.85 5.00 5.15 V

Dropout Voltage I

OUT1

= 250mA 400 600 mV

I

OUT1

= 100µA 100 150 mV

Line Regulation 6V ² V

IN

² 26V 5 50 mV

Load Regulation 1mA ² I

OUT1

² 250mA, VIN= 14V 5 50 mV

Quiescent Current ENABLE = HIGH, V

IN

= 16V, 22 50 mA

I

OUT1

= 250mA

Ripple Rejection f = 120Hz, I

OUT1

= 125mA, 7V ² VIN² 17V 60 70 dB

Current Limit 260 400 mA
Short Circuit Current Limit V

OUT1

= 0V, VIN= 16V 25 mA

Reverse Current V

OUT1

= 5V, VIN= 0V 100 1500 µA

■ Secondary Output (V

OUT2

)

Output Voltage, V

OUT2

100µA ² I

OUT2

² 100mA 4.85 5.00 5.15 V

Dropout Voltage I

OUT2

= 100mA 400 600 mV

I

OUT2

= 100µA 100 150 mV

Line Regulation 6V ² V

IN

² 26V 5 50 mV

Load Regulation 100µA ² I

OUT2

² 100mA, VIN= 14V 5 50 mV

Quiescent Current ENABLE = LOW, V

IN

= 12.8V 100 150 µA

ENABLE = HIGH, V

IN

= 16V, 8 25 mA

I

OUT2

= 100mA

Ripple Rejection f = 120Hz, I

OUT2

= 50mA, 7V ² VIN² 17V 60 70 dB

Current Limit 105 200 mA
Short Circuit Current Limit V

OUT2

= 0V, VIN= 16V, I

OUT1

= 0A 25 mA

Reverse Current V

OUT2

= 5V, VIN= 0V 100 250 µA

■ Enable Function (ENABLE)

Input Threshold ENABLE = LOW, 7V ² V

IN

² 26V 1.2 0.8 V

ENABLE = HIGH, 7V ² V

IN

² 26V 2.0 1.2 V

Input Bias Current 0V ² V

ENABLE

²5V -2 0 2 µA

■ Protection Circuits

Overtemperature Threshold 150 180 ¡C
Overvoltage Shutdown 30 34 38 V

Definition of Terms

3

CS8281

V

IN

ENABLE

V

OUT

1

System

Condition

60V

3V

2.4V

5V

0V

Turn

On

Load

Dump

Low V

IN

Line Noise, Etc. V

OUT2

Short

Circuit

Thermal

Shutdown

Turn

Off

5V

0V

14V

5V

2.0V

0.8V

14V

26V

31V

5V 5V

2.4V

5V5V

5V

0V

V

OUT

2

5V

5V

0V

5V

V

OUT

1

Short

Circuit

0V

5V

5V

Typical Circuit Waveform

PACKAGE LEAD # LEAD SYMBOL FUNCTION

Package Lead Description

5 Lead D

2

PAK

1V

IN

Supply voltage to IC, usually direct from battery.

2V

OUT1

5V regulated output which is activated by ENABLE input.

3 Gnd Ground connection.

4V

OUT2

Standby output 5V, 100mA capability; always on.

5 ENABLE CMOS compatible input lead; switches V

OUT1

. When ENABLE is

high, V

OUT1

is active.

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 V

OUT

The percentage change in output voltage for a thermal varia­tion from room temperature to either temperature extreme.

The CS8281 is a micropower dual 5V regulator. All bias
required to operate the internal circuitry is derived from
the standby output, V

OUT2

. If this output experiences an

over current situation and collapses, then V

OUT1

will also

collapse (see timing diagrams).

If there is critical circuitry that must remain active under
most conditions it should be connected to V

OUT2

. Any cir­cuitry that is likely to be subjected to a short circuit, e.g.,
circuitry outside the module, should be connected to V

OUT1

.

Output capacitors are required for stability with the CS8281.
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 -40ûC, capacitors rated at that temperature must be
used.

More information on capacitor selection for Smart
Regulatorsª is available in the Smart Regulator applica­tion note, Compensation for Linear Regulators.

The ENABLE function controls V

OUT1

. When ENABLE is

high, V

OUT1

is on. When ENABLE is low, V

OUT1

is off.

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

PD(max) = {V

IN

(max)ÐV

OUT1

(min)}I

OUT1

(max)+

{V

IN

(max)ÐV

OUT2

(min)}I

OUT2

(max)+VIN(max)IQ(1)

where:

V

IN

(max) is the maximum input voltage,

V

OUT1

(min) is the minimum output voltage from V

OUT1

,

V

OUT2

(min) is the minimum output voltage from V

OUT2

,

I

OUT1

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

cation,

I

OUT2

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

cation, and

IQis the quiescent current the regulator consumes at both
I

OUT1

(max) and I

OUT2

(max).

Once the value of PD(max) is known, the maximum per­missible value of R

QJA

can be calculated:

R

QJA

= (2)

The value of R

QJA

can then be compared with those in
the package section of the data sheet. Those packages with
R

QJA

'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 heat
sink will be required.

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

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 R

QJA

.

R

QJA

= R

QJC

+ R

QCS

+ R

QSA

(3)

where:

R

QJC

= the junctionÐtoÐcase thermal resistance,

R

QCS

= the caseÐtoÐheat sink thermal resistance, and

R

QSA

= the heat sinkÐtoÐambient thermal resistance.

R

QJC

appears in the package section of the data sheet. Like

R

QJA

, it too is a function of package type. R

QCS

and R

QSA

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.

Heat Sinks

150¡C - T

A

P

D

Calculating Power Dissipation

in a Dual Output Linear Regulator

ENABLE

External Capacitors

General

4

CS8281

Application Notes

I

V

IN

IN

Smart

Regulator

Control
Features

}

I

Q

I

OUT1

I

OUT2

V

V

OUT1

OUT2

5

CS8281

Test & Application Circuit

ENABLE

V

IN

V

OUT

1

CS8281

Gnd

22mF
ESR<8W

V

CC

I/O

mP

Gnd

Load

0.1mF

V

BATT

C

2

C

1

C

3

V

OUT

2

22mF

ESR<8W

* 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.

Part Number Description

CS8281YDP5 5 Lead D2PAK
CS8281YDPR5 5 Lead D

2

PAK (tape & reel)

6

Rev. 9/16/97 © 1999 Cherry Semiconductor Corporation

CS8281

Ordering Information

Thermal Data 5 Lead D2PAK

R

QJC

typ 2.4 ¡C/W

R

QJA

typ 10-50* ¡C/W

* Depending on thermal properties of substrate. R

QJA

= R

QJC

+ R

QCA

Package Specification

PACKAGE THERMAL DATAPACKAGE DIMENSIONS IN MM(INCHES)

Cherry Semiconductor Corporation reserves the
right to make changes to the specifications without
notice. Please contact Cherry Semiconductor
Corporation for the latest available information.

5 Lead D2PAK (DP)

1.70 (.067) REF

0.10 (.004)

0.00 (.000)

10.31 (.406)

10.05 (.396)

0.91 (.036)

0.66 (.026)

1.40 (.055)

1.14 (.045)

4.57 (.180)

4.31 (.170)

1.68 (.066)

1.40 (.055)

2.74(.108)

2.49(.098)

.254 (.010) REF

2.79 (.110)

2.29 (.090)

15.75 (.620)

14.73 (.580)

8.53 (.336)

8.28 (.326)