FAN2535S26X Datasheet FAN2535S285X, FAN2535S26X | P4-P6

REV. 1.0.2 8/26/03

FAN2534/FAN2535 PRODUCT SPECIFICATION

Switching Characteristics

(Notes 4, 5)

AC Performance Characteristics

(Notes 4, 5)

Notes:

1. Functional operation under any of these conditions is NOT implied. Performance and reliability are guaranteed only

if Operating Conditions are not exceeded.

2. Using Mil Std. 883E, method 3015.7(Human Body Model), 400V when using JEDEC method A115-A (Machine Model).

3. For specific output voltages of the fixed oputput voltage versions please refer to the table: "Output Voltage Options and

Ordering Information" on Page 9. Custom fixed output voltages, not listed in the table, are also available.

4. Unless otherwise stated, T

= 25°C, V

= V

OUT

+ 1V, I

OUT

= 100µA, V

> 2.0 V.

5. Bold values indicate -40 <T

<125°C.

6. Dropout Voltage is defined as the input to output differential at which the output voltage drops to 2% below the nominal value

measured at 1V input - output differential.

7. Adjustable version, has a bandgap reference voltage of 1.0V, trimmed to +/-1% initial accuracy.

8. When using repeated cycling, F>0.5Hz.

Parameter Conditions Min. Typ. Max. Unit

Enable Response time (Note 8) C

=10µF C

=10nF 150

300

µsec

Power "ON" Response time C

=10uF C

=10nF

OUT

= 3.0V

150

500

µsec

Error Flag Response time

(FAN2535-XX only)

msec

Symbol Parameter Conditions Min. Typ. Max. Units

∆

OUT

∆

Line regulation V

= (V

OUT

+ 1) to 6.5V, I

= 10mA 0.05 0.2 %

∆

OUT

Load regulation I

OUT

= 0.1 to 100mA 1.0 2.0 %

Output noise BW: 300Hz–50KHz

OUT

= 10µF,

BYP

= 0.01µF

50 µV

RMS

PSRR Power Supply

Ripple Rejection

100 Hz,

OUT

= 1µF,

BYP

= 0.01µF

0mA<I

<150mA

70 dB

REV. 1.0.2 8/26/03 5

PRODUCT SPECIFICATION FAN2534/FAN2535

Functional Description

Utilizing CMOS technology, the FAN2534/FAN2535

product family is optimized for use in compact battery

powered systems, offering a unique combination of high

ripple rejection, low noise, low power consumption,

extremely low dropout voltages, high tolerance for a variety

of output capacitors, and less than 1µA "OFF" current.

In the circuit, a differential ampliﬁer controls a series-pass

P-Channel MOSFET, and a separate error ampliﬁer com-

pares the load voltage at the output with an onboard trimmed

low voltage bandgap reference. The series resistance of the

pass P-Channel MOSFET is approximately 1 Ohm, yielding

an unusually low dropout voltage even under high load

conditions.

Thermal shutdown and current limit circuits protect the

device under extreme conditions. When the device tempera-

ture reaches 155°C, the output is disabled, until the device

cooles down by 15°C, then re-enabled. The user can to shut

down the device using the Enable control pin at any time.

The current limit circuit is trimmed, which leads to consis-

tent power on /enable delays, and provides safe short circuit

current densities even in narrow traces of the PCB.

A carefully optimized control loop accommodates a wide

range of ESR values in the output bypass capacitor, allowing

the user to optimize space, cost, and performance require-

ments.

An Enable pin shuts down the regulator output to conserve

power, reducing supply current to less than 1µA. The output

can then be re-Enabled within 150µSec, fulﬁlling the fast

power-cycling needs of CDMA applications.

Depending on the device type selected, other control and

status functions are available at pin 4. The ﬁxed-voltage

versions are available with either a noise-bypass pin or an

Error ﬂag pin option. The error ﬂag can be used as a diagnos-

tic function to indicate that the output voltage has dropped

more than 5% below the nominal value.

The adjustable-voltage versions utilize pin 4 to connect to an

external voltage divider which feeds back to the regulator

error ampliﬁer, thus setting the output voltage to the desired

value.

Applications Information

External Capacitors – Selection

The FAN2534/FAN2535 allows the user to utilize a wide

variety of capacitors compared to other LDO products.

An innovative design approach offers signiﬁcantly reduced

sensitivity to ESR (Equivalent Series Resistance), which

degrades regulator loop stability in older designs. While the

improvements featured in the FAN2534/FAN2535 family

greatly simplify the design task, capacitor quality still must

be considered if the designer is to achieve optimal circuit

performance. In general, ceramic capacitors offer superior

ESR performance, and a smaller case size than tantalums.

Input Capacitor

An input capacitor of 2.2µF (nominal value) or greater,

connected between the Input pin and Ground, placed in close

proximity to the device, will improve transient response and

ripple rejection. Higher values will further improve ripple

rejection and transient response. An input capacitor is

recommended when the input source, either a battery or

a regulated AC voltage, is located far from the device.

Any good quality ceramic, tantalum, or metal ﬁlm capacitor

will give acceptable performance, however in extreme cases

capacitor surge current ratings may have to be considered.

Output Capacitor

An output capacitor is required to maintain regulator loop

stability.

Stable operation will be achieved with a wide

variety of capacitors with ESR values ranging from 0mΩ

up to 400mΩ. Multilayer ceramic, tantalum or aluminum

electrolytic capacitors may be used. A nominal value of at

least 1µF is recommended. Note that the choice of output

capacitor effects load transient response, ripple rejection,

and it has a slight effect on noise performance as well.

Bypass Capacitor (FAN2534-XX Only)

In the ﬁxed-voltage conﬁguration, connecting a capacitor

between the bypass pin and ground can signiﬁcantly reduce

output noise. Values ranging from 0pF to 47nF can be used,

depending on the sensitivity to output noise in the application.

At the high-impedance Bypass pin, care must be taken in the

PCB layout to minimize noise pickup, and capacitors must

be selected to minimize current loading (leakage). Noise

pickup from external sources can be considerable. Leakage

currents into the Bypass pin will directly affect regulator

accuracy and should be kept as low as possible; thus, high-

quality ceramic and ﬁlm types are recommended for their

low leakage characteristics. Cost-sensitive applications not

concerned with noise can omit this capacitor.

FAN2534/FAN2535 PRODUCT SPECIFICATION

6 REV. 1.0.2 8/26/03

Control Functions

Enable Pin

Connecting 2.0V or greater to the Enable pin will enable the

output, while 0.4V or less will disable it while reducing the

quiescent current consumption to less than 1µA. If this

shutdown function is not needed, the pin can simply be

connected permanently to the V

pin. Allowing this pin

to ﬂoat will cause erratic operation.

Error Flag (FAN2535-XX Only)

Fault conditions such as input voltage dropout

(low V

), overheating, or overloading (excessive output

current), will set an error ﬂag: The ERR pin which is an

open-drain output, will go LOW when V

OUT

is less than

95% or the speciﬁed output voltage. When the voltage at

OUT

is greater than 95% of the speciﬁed output voltage,

the ERR pin is HIGH. A logic pullup resistor of 100K Ohm

is recommended at this output. The pin can be left discon-

nected if unused.

Thermal Protection

The FAN2534/FAN2535 is designed to supply high peak

output currents for brief periods, however sustained exces-

sive output load at high input - output voltage difference

will cause the device temperature to increase and exceed

maximum ratings due to power dissipation. During output

overload conditions, when the die temperature exceeds the

shutdown limit temperature of 155°C, an onboard thermal

protection will disable the output until the temperature drops

approximately 15°C below the limit, at which point the

output is re-enabled. During a thermal shutdown situation

the user may assert the power-down function at the Enable

pin, reducing power consumption to a minimum.

Thermal Characteristics

The FAN2534/FAN2535 is designed to supply 150mA at

the speciﬁed output voltage with an operating die (junction)

temperature of up to 125°C. Once the power dissipation and

thermal resistance is known, the maximum junction tempera-

ture of the device can be calculated. While the power dissipa-

tion is calculated from known electrical parameters, the

actual thermal resistance depends on the thermal characteris-

tics of the SOT23-5 surface-mount package and the

surrounding PC Board copper to which it is mounted.

The power dissipation is equal to the product of the input-to-

output voltage differential and the output current plus the

ground current multiplied by the input voltage, or:

The ground pin current I

GND

can be found in the charts

provided in the Electrical Characteristics section.

The relationship describing the thermal behavior of the

package is:

where T

J(max)

is the maximum allowable junction tempera-

ture of the die, which is 125°C, and T

is the ambient operat-

ing temperature. θ

is dependent on the surrounding PC

board layout and can be empirically obtained. While the θ

(junction-to-case) of the SOT23-5 package is speciﬁed at

130°C /W, the θ

of the minimum PWB footprint will be at

least 235°C /W. This can be improved upon by providing a

heat sink of surrounding copper ground on the PWB.

Depending on the size of the copper area, the resulting θ

can range from approximately 180°C /W for one square inch

to nearly 130°C /W for 4 square inches. The addition of

backside copper with through-holes, stiffeners, and other

enhancements can also aid in reducing thermal resistance.

The heat contributed by the dissipation of other devices

located nearby must be included in the design consider-

ations. Once the limiting parameters in these two relation-

ships have been determined, the design can be modiﬁed to

ensure that the device remains within speciﬁed operating

conditions. If overload conditions are not considered, it is

possible for the device to enter a thermal cycling loop, in

which the circuit enters a shutdown condition, cools, re-

enables, and then again overheats and shuts down repeatedly

due to an unmanaged fault condition.

Adjustable Version

The FAN2534 adjustable version includes an input pin ADJ

which allows the user to select an output voltage ranging

from 2.5V to near V

, using an external resistor divider. The

voltage V

ADJ

presented to the ADJ pin is fed to the onboard

error ampliﬁer which adjusts the output voltage until V

ADJ

equal to the onboard bandgap reference voltage of

1.00V(typ). The equation is:

Since the bandgap reference voltage is trimmed, 1% initial

accuracy can be achieved. The total value of the resistor

chain should not exceed 250K Ohm total to keep the error

ampliﬁer biased during no-load conditions. Programming

output voltages very near V

need to allow for the magni-

tude and variation of the dropout voltage V

over load,

supply, and temperature variations. Note that the low-leak-

age FET input to the CMOS Error Ampliﬁer induces no bias

current error to the calculation.

OUT

–()I

OUT

GND

D max()

J max()

–

-------------------------------







OUT

1.00V 1

upper

lower

----------------+×=

P1-P3 P4-P6 P7-P9 P10-P11

FAN2535S26X

Mfr. #:

Buy FAN2535S26X

Manufacturer:

ON Semiconductor

Description:

IC REG LINEAR 2.6V 150MA SOT23-5

Lifecycle:

New from this manufacturer.

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FAN2535S26X

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