Features

STBY

Gnd

Current

Limit

Overvoltage

Shutdown

OVSD

TSD

Thermal

Shutdown

Current

Limit

Bandgap

RESET

Adj

OVSD

TSD

STANDBY

RESET

OVSD

TSD

TRK

250mA

5V,100mA,2%

ENABLE

RESET

2 Regulated Outputs

Standby Output 5V

±2%; 100mA

Tracking Output 5V;

250mA

Low Dropout Voltage

(0.4V at rated current)

RESET Option

ENABLE Option

Low Quiescent Current

Protection Features
Independent Thermal

Shutdown

Short Circuit
60V Load Dump
Reverse Battery

Package Options

7L TO-220

CS8361

5V Dual Micropower Low Dropout

Regulator with ENABLE and RESET

CS8361

Block Diagram

Description

7L D

PAK

16 Lead PDIP & SOIC Wide

(internally fused leads)

Gnd

TRK

Adj

ENABLE

RESET

STBY

1. V

STBY

2. V

3. V

TRK

4. Gnd
5. Adj
6. ENABLE
7. RESET

Also available in 20 Lead SOIC Wide.
Consult factory for 20 Lead PSOP .

* Consult factory for positive ENABLE option.

Rev. 5/4/99

The CS8361 is a precision micro-
power dual voltage regulator with

and

The 5V standby output is accurate
within ±2% while supplying loads
of 100mA and has a typical
dropout voltage of 400mV.
Quiescent current is low, typically
140µA with a 300µA load. The
active

output monitors the

5V standby output and holds
the

line low during power-

up and regulator dropout condi-
tions. The

circuit includes

hysteresis and is guaranteed to
operate correctly with 1V on the
standby output.

The second output tracks the 5V
standby output through an external
adjust lead, and can supply loads
of 250mA with a typical dropout
voltage of 400mV. The logic level

lead is used to control

this tracking regulator output.

Both outputs are protected against
overvoltage, short circuit, reverse
battery and overtemperature condi-
tions. The robustness and low qui-
escent current of the CS8361 makes
it not only well suited for automo-
tive microprocessor applications,
but for any battery powered micro-
processor applications.

ENABLE

RESET

ENABLE

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

Electrical Characteristics:

6V ² V

² 26V, I

OUT1

= I

OUT2

= 100µA, -40¡C ² T

²+125¡C, -40¡C ²T

² +150¡C,

unless otherwise specified.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

CS8361

Absolute Maximum Ratings

Supply Voltage, V

.....................................................................................................................................................-16V to 26V

Positive Transient Input Voltage, tr > 1ms.............................................................................................................................60V
Negative Transient Input Voltage, T < 100ms, 1% Duty Cycle..........................................................................................-50V
Input Voltage Range (

) ...............................................................................................................-0.3V to 10V

Junction Temperature...........................................................................................................................................-40¡C to +150¡C
Storage Temperature Range ................................................................................................................................-55¡C to +150¡C
ESD Susceptibility (Human Body Model)..............................................................................................................................2kV
Lead Temperature Soldering

Wave Solder (through hole styles only) .....................................................................................10 sec. max, 260¡C peak
Reflow (SMD styles only) ......................................................................................60 sec. max above 183¡C, 230¡C peak

RESET

ENABLE

s Tracking Output (V

TRK

)

STBY

Ð V

TRK

6V ² V

² 26V

-25

+25

TRK

Tracking Error

100µA ² I

TRK

² 250mA (note 1)

Adjust Pin Current, I

Adj

Loop in Regulation

1.5

µA

Line Regulation

6V ² V

² 26V (note 1)

Load Regulation

100µA ² I

TRK

² 250mA (note 1)

Dropout Voltage (V

Ð V

TRK

) I

TRK

= 100µA

100

150

TRK

= 250mA

400

700

Current Limit

= 12V, V

TRK

= 4.5

275

500

Quiescent Current

= 12V, I

TRK

= 250mA

No Load on V

STBY

Reverse Current

TRK

= 5V, V

= 0V

200

1500

µA

Ripple Rejection

f = 120Hz, I

TRK

= 250mA

7V ² V

² 17V

s Standby Output (V

STBY

)

Output Voltage, V

STBY

6V ² V

² 26V

4.90

5.00

5.10

100µA ² I

STBY

² 100mA

Line Regulation

6V ² V

² 26V

Load Regulation

100µA ² I

STBY

² 100mA

Dropout Voltage (V

Ð V

STBY

) I

STBY

= 100µA

100

150

STBY

= 100mA

400

600

Current Limit

= 12V, V

STBY

= 4.5V

125

200

Short Circuit Current

= 12V, V

STBY

= 0V

100

Quiescent Current

= 12V, I

STBY

= 100mA

TRK

= 0mA

= 12V, I

STBY

= 300µA

140

200

µA

TRK

= 0mA

Reverse Current

STBY

= 5V, V

= 0V

100

200

µA

Ripple Rejection

f = 120Hz, I

STBY

= 100mA

7V ² V

² 17V

Note 1: V

TRK

connected to Adj lead. V

TRK

can be set to higher values by using an external resistor divider.

CS8361

Package Lead Description

PACKAGE LEAD #

LEAD SYMBOL

FUNCTION

Electrical Characteristics:

6V ² V

² 26V, I

OUT1

= I

OUT2

= 100µA, -40¡C ² T

²+125¡C, -40¡C ²T

² +150¡C,

unless otherwise specified.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Functions

Input Threshold

0.8

1.2

2.0

Input Bias Current

ENABLE

= 0V to 10V

-10

µA

Threshold High (V

)

STBY

Increasing

4.59

4.87

STBY

-0.02

Hysteresis

120

180

Threshold Low (V

)

STBY

Decreasing

4.53

4.75

STBY

-0.08

Leakage

µA

Output Voltage

Low (V

RLO

); R

RST

= 10k½

1V ² VS

TBY

² V

0.1

0.4

Low (V

RPEAK

)

STBY

, Power Up, Power Down

0.6

1.0

s Protection Circuitry (Both Outputs)

Independent Thermal Shutdown V

STBY

150

180

¡C

TRK

150

165

¡C

Overvoltage Shutdown

RESET

ENABLE

ENABLE

RESET

16L PDIP & SO

20L SO Wide

Wide

(Internally

TO-220 D

PAK

Fused Leads)

STBY

Standby output voltage delivering 100mA.

Input voltage.

TRK

Tracking output voltage controlled by

delivering 250mA.

4,5,12,13

4,5,6,7

Gnd

Reference ground connection.

14,15,16,17

Adj

Resistor divider from V

TRK

to Adj. Sets the

output voltage on V

TRK

. If tied to V

TRK

, V

TRK

will track V

STBY

Provides on/off control of the tracking output,
active LOW.

CMOS compatible output lead that goes low
whenever V

STBY

falls out of regulation.

2,7,10,

3,9,12,13,

No Connection.

11,14,15

18,19

RESET

ENABLE

CS8361

Circuit Description

Application Notes

The

function switches the output transistor for

TRK

on and off. When the

lead voltage exceeds

1.4V(typ), V

TRK

turns off. This input has several hundred

millivolts of hysteresis to prevent spurious output activity
during power-up or power-down.

The

is an open collector NPN transistor, con-

trolled by a low voltage detection circuit sensing the V

STBY

(5V) output voltage. This circuit guarantees the
output stays below 1V (0.1V typ) when V

STBY

is as low as

1V to ensure reliable operation of microprocessor-based
systems.

This output uses the same type of output device as V

STBY

but is rated for 250mA. The output is configured as a
tracking regulator of the standby output. By using the
standby output as a voltage reference, giving the user an
external programming lead (Adj lead), output voltages
from 5V to 20V are easily realized. The programming is
done with a simple resistor divider (Figure 2), and follow-
ing the formula:

TRK

= V

STBY

´ (1 + R1/R2) + I

Adj

´ R1

If another 5V output is needed, simply connect the Adj
lead to the V

TRK

output lead.

TRK

Output Voltage

RESET

RESET Function

ENABLE

ENABLE Function

Output capacitors for the CS8361 are required for stability.
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. Worst-
case 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 char-
acteristic 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 applica-
tion note, ÒCompensation for Linear Regulators.Ó

The maximum power dissipation for a dual output regula-
tor (Figure 1) is:

PD(max) = {V

(max)ÐV

OUT1

(min)}I

OUT1

(max)+

(max)ÐV

OUT2

(min)}I

OUT2

(max)+V

(max)IQ (1)

Where

(max) is the maximum input voltage,

OUT1

(min) is the minimum output voltage from V

OUT1

OUT2

(min) is the minimum output voltage from V

OUT2

OUT1

(max) is the maximum output current, for the

application

OUT2

(max) is the maximum output current, for the

application

is the quiescent current the regulator consumes at

OUT

(max).

Once the value of PD(max) is known, the maximum per-
missible value of R

QJA

can be calculated:

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.

OUT

Control
Features

}

OUT

Smart

Regulator

150¡C - T

Calculating Power Dissipation

in a Dual Output Linear Regulator

External Capacitors

STBY

CS8361

Gnd

ESR<8

I/O

MCU

Gnd

B+

C2**

C1*

TRK

RESET

ENABLE

RESET

5V, 100mA

Adj

ESR<8

C3**

SW 8V,
250mA

* C1 is required if regulator is located far from power supply filter.
** C2 and C3 are required for stability.

TRK

~ V

STBY

(1 + R1/R2)

For V

TRK

~ 8V, R1/R2 ~ 0.6

0.1

CS8361

Test & Application Circuits

STBY

CS8361

Gnd

ESR<8

I/O

MCU

Gnd

B+

C2**

C1*

TRK

RESET

ENABLE

RESET

5V, 100mA

Adj

ESR<8

C3**

SW 5V,
250mA

0.1

* C1 is required if regulator is located far from power supply filter.
** C2 and C3 are required for stability.

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

QJC

+ R

QCS

+ R

QSA

(3)

where:

QJC

= the junctionÐtoÐcase thermal resistance,

QCS

= the caseÐtoÐheat sink thermal resistance, and

QSA

= the heat sinkÐtoÐambient thermal resistance.

QJC

appears in the package section of the data sheet. Like

QJA

, it too is a function of package type. R

QCS

and R

QSA

are functions of the package type, heat sink and the inter-
face between them. These values appear in heat sink data
sheets of heat sink manufacturers.

Heat Sinks

Application Notes: continued

Figure 2: 5V, 8V Regulator

Figure 3: Dual 5V Regulator

Part Number CS8361