Datasheet SC1566I5M-1.8.TR, SC1566I5M-2.5.TR, SC1566I5T, SC1566I5T-1.8, SC1566I5T-2.5 Datasheet (Semtech Corporation)

1 www.semtech.com

SC1566

Very Low Dropout

3.0 Amp Regulator With Enable

POWER MANAGEMENT

VIN

ENABLE

VO = See equation below

C1

C2

R1

R2

U1
SC1566I5T-2.5

1

2

3

4

5

VIN

EN

GND

ADJ

VO

VIN

ENABLE

VO = 2.5V

C1

C2

U1
SC1566I5T-2.5

1

2

3

4

5

VIN

EN

GND

ADJ

VO

VIN VO = 1.8V

C1

C2

U1
SC1566IT-1.8

1

2

3

VIN

GND

VO

Revision 1, January 2001

The SC1566 is a high performance positive voltage
regulator designed for use in applications requiring very
low dropout voltage at up to 3 Amps. Since it has
superior dropout characteristics compared to regular
LDOs, it can be used to supply 2.5V on motherboards or

2.8V on peripheral cards from the 3.3V supply thus
allowing heat sink size reduction or elimination.
Additionally, the five pin versions of SC1566 have an
enable pin, to further reduce power dissipation while shut
down. The SC1566 provides excellent regulation over
variations in line, load and temperature.

The SC1566 is available as three terminal fixed output
voltage and five terminal fixed or adjustable output
voltage devices with enable. Two package options are
available: TO-263 and TO-220.

u 350mV dropout @ 3A
u Adjustable output from 1.2V to 4.8V
u 2.5V and 1.8V options (5 pin parts also adjustable

externally using resistors)

u Over current and over temperature protection
u Enable pin
u 10µA quiescent current in shutdown
u Low reverse leakage (output to input)
u Full industrial temperature range
u TO-220 and TO-263 packages

u Battery powered systems
u Motherboards and notebook computers
u Peripheral cards
u Network cards
u Set top boxes
u Medical equipment

Volts

R2

R2)(R1 1.200VO+

=

FeaturesDescription

Applications

Typical Application Circuits

(1)(2)

Notes:

(1) Maximum VO setpoint for 1.8V parts = 5.4V
(2) This device is designed to operate with
ceramic input and output capacitors

2ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

retemaraP lobmySxaMstinU

egatloVtupnI V

NI

5.5V

noitapissiDrewoP P

D

detimiLyllanretnIW

tneibmAotnoitcnuJecnatsiseRlamrehT

)362-OT(MI6651CS

)022-OT(TI6651CS

q

AJ

06
05

W/C°

esaCotnoitcnuJecnatsiseRlamrehT

)362-OT(MI6651CS

)022-OT(TI6651CS

q

CJ

3
3

W/C°

egnaRerutarepmeTtneibmAgnitarepO T

A

58+ot04-C°

egnaRerutarepmeTnoitcnuJgnitarepO T

J

051+ot04-C°

egnaRerutarepmeTegarotS T

GTS

051+ot56-C°

.ceS01)gniredloS(erutarepmeTdaeL T

DAEL

003C°

)ledoMydoBnamuH(gnitaRDSE V

DSE

2Vk

retemaraPlobmySsnoitidnoCtseTniMpyTxaMstinU

NIV

egnaRegatloVylppuSV

NI

2.25.5 V

tnerruCtnecseiuQI

Q

V

NI

V3.3=57.0 57.1 Am

V

NI

V,V5.5=

NE

V0=01 53 Aµ

OV

egatloVtuptuO

)1(

V

O

VNIV=

O

I,V7.0+

O

Am01=%1-VO%1+V

)egatloVdexiFlanretnI(

%2-%2+

noitalugeReniL

)1(

GER

)ENIL(

V

NI

V(=

O

I,V5.5ot)V52.0+

TUO

Am01=530.0 3.0 %

noitalugeRdaoL

)1(

GER

)DAOL(

VNIV=

O

V7.0+2.0 4.0 %

egatloVtuoporD

)2()1(

V

D

I

O

Am01=15Vm

01

I

O

Am005=57001Vm

051

Absolute Maximum Ratings

Electrical Characteristics

Unless specified: VEN = VIN. Adjustable Option (V

ADJ

> V

TH(ADJ)

): VIN = 2.2V to 5.5V and IO = 10µA to 3A.

Fixed Options (V

ADJ

= GND): VIN = (VO + 0.7V) to 5.5V and IO = 0A to 3A. Values in bold apply over the full operating temperature range.

3ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

Notes:

(1) Low duty cycle pulse testing with Kelvin connections required.
(2) Defined as the input to output differential at which the output voltage drops to 1% below the value
measured at a differential of 0.7V.
(3) Required to maintain regulation. Voltage set resistors R1 and R2 are usually utilized to meet this
requirement. Adjustable versions only.
(4) Guaranteed by design.
(5) When V

ADJ

exceeds this threshold, the Sense Select switch disconnects the internal feedback chain from

the error amplifier and connects V

ADJ

instead.

retemaraPlobmySsnoitidnoCtseTniMpyTxaMstinU

).tnoC(OV

egatloVtuoporD

)2()1(

I

O

A5.1=002003Vm

004

I

O

A3=053054Vm

006

tnerruCdaoLmuminiM

)3(

I

O

VNIV=

O

V7.0+101 Aµ

timiLtnerruCI

LC

0.3 5.4 5.6 A

JDA

egatloVecnerefeR

)1(

V

FER

V

NI

V,V2.2=

JDA

V=

TUOI,O

Am01=881.1002.1212.1V

671.1422.1

tnerruCniPtsujdA

)4(

I

JDA

V

JDA

V=

FER

01 05 An

dlohserhTniPtsujdA

)5(

V

)JDA(HT

01.0 02.0 04.0 V

NE

tnerruCniPelbanEI

NE

V

NE

V,V0=

NI

V3.3=5.1 01 Aµ

dlohserhTniPelbanEV

HI

V

NI

V3.3= 8.1 V

V

LI

V

NI

V3.3= 4.0

noitcetorPerutarepmeTrevO

levelpirThgiHT

IH

571C°

siseretsyHT

TSYH

01C°

Electrical Characteristics (Cont.)

Unless specified: VEN = VIN. Adjustable Option (V

ADJ

> V

TH(ADJ)

): VIN = 2.2V to 5.5V and IO = 10µA to 3A.

Fixed Options (V

ADJ

= GND): VIN = (VO + 0.7V) to 5.5V and IO = 0A to 3A. Values in bold apply over the full operating temperature range.

4ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

emaNniPnoitpicseDniP

JDA lanretxefI.srotsiserkcabdeeflanretniehtybtestahtotegatlovtuptuoehtstes,dednuorgnehw,nipsihT

:)1egapnostiucriCnoitacilppAeeS(eblliwegatlovtuptuoeht,desuerasrotsiserkcabdeef

NE fonoitcarfaottnerructnecseiuqehtgnicuder,fforotalugerehtsnrutV4.0wolebnipsihtgnilluP.tupnIelbanE

.desugniebtonfiNIVottcennoC.nepotfelsinipsihtfidelbaneeblliwecivedehT.eulavgnitareposti

DNG .gniknistaehrof)DNGotdetcennocyllacirtcele(batehtesU.dnuorgecnerefeR

NIV muminiM.V5.5dna)V7.0+OV(neewtebebtsumnipsihtottupnieht,daollluftanoitalugerroF.egatlovtupnI

.V2.2=NIV

OV.ecivedehtfotuptuorewopehtsinipsihT

Volts

R2

R2)(R11.200VO+

=

Pin Descriptions

Pin Configurations

Note:

(1) 3-pin versions are fixed output
voltage only.

NIP-56651CS

snoisreV

niPnoitcnuF

1NIV

2NE

3DNG

4JDA

5OV

DNGSIBAT

Ordering Information

TO-263-5

TO-220-5

TO-263-3

NIP-36651CS

snoisreV

niPnoitcnuF

1NIV

2DNG

3OV

DNGSIBAT

TO-220-3

Notes:

(1) Where -X.X denotes voltage options. Available
voltages are: 2.5V and 1.8V.
(2) Output voltage can be adjusted using external
resistors, see Pin Descriptions below.
(3) Only available in tape and reel packaging. A reel
contains 800 devices.
(6) Only available in tube packaging. A tube contains 50
devices.

eciveD

)1(

egakcaP

RT.X.X-MI6651CS3-362-OT

)3(

RT.X.X-M5I6651CS

)2(

5-362-OT

)3(

X.X-TI6651CS3-022-OT

)4(

X.X-T5I6651CS

)2(

5-022-OT

)4(

Block Diagram

* 5 lead versions only

5ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

Typical Characteristics

Dropout Voltage vs. Output Current

vs. Junction Temperature

Dropout Voltage vs. Junction

Temperature vs. Output Current

Output Voltage (2.5V) vs. Junction

Temperature vs. Output Current

Output Voltage (2.5V) vs. Junction

Temperature vs. Output Current

Reference Voltage vs. Junction

Temperature vs. Output Current

Reference Voltage vs. Junction

Temperature vs. Output Current

0

50

100

150

200

250

300

350

400

450

500

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

I

O

(A)

V

D

(mV)

0°C

-40°C

150°C

25°C

0

50

100

150

200

250

300

350

400

450

500

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

V

D

(mV)

IO = 0.5A

I

O

= 1.5A

I

O

= 3A

2.450

2.460

2.470

2.480

2.490

2.500

2.510

2.520

2.530

2.540

2.550

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

VO (V)

IO = 3A

I

O

= 10mA

VIN = 3.2V

2.450

2.460

2.470

2.480

2.490

2.500

2.510

2.520

2.530

2.540

2.550

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

VO (V)

IO = 3A

I

O

= 10mA

VIN = 5.5V

1.175

1.180

1.185

1.190

1.195

1.200

1.205

1.210

1.215

1.220

1.225

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

V

REF

(V)

VIN = 2.2V

I

O

= 10mA

I

O

= 3A

1.175

1.180

1.185

1.190

1.195

1.200

1.205

1.210

1.215

1.220

1.225

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

V

REF

(V)

VIN = 5.5V

I

O

= 10mA

I

O

= 3A

6ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

Introduction

The SC1566 is intended for applications such as
graphics cards where high current capability and very low
dropout voltage are required. It provides a very simple,
low cost solution that uses very little pcb real estate and
typically does not require a heatsink. Additional features
include an enable pin to allow for a very low power
consumption standby mode, and a fully adjustable
output (5-pin versions).

Component Selection

Input capacitor: a 4.7µF or 10µF ceramic capacitor is

recommended. This allows for the device being some
distance from any bulk capacitance on the rail.
Additionally, input droop due to load transients is reduced,
improving load transient response. Additional capacitance
may be added if required by the application.

Output capacitor: a minimum bulk capacitance of 22µF,
along with a 0.1µF ceramic decoupling capacitor is
recommended. Increasing the bulk capacitance will
improve the overall transient response. The use of
multiple lower value ceramic capacitors in parallel to
achieve the desired bulk capacitance will not cause
stability issues. Although designed for use with ceramic
output capacitors, the SC1566 is extremely tolerant of
output capacitor ESR values and thus will also work
comfortably with tantalum output capacitors.

Applications Information

External voltage selection resistors (5-pin parts): the
use of 1% resistors, and designing for a current flow
³ 10µA is recommended to ensure a well regulated
output (thus R2 £ 120kW).

Thermal Considerations

The power dissipation in the SC1566 is approximately
equal to the product of the output current and the input
to output voltage differential:

()

OD

IVOUTVINP •−≈

The absolute worst-case dissipation is given by:

(

)

)MAX(Q)MAX()MAX(O)MIN()MAX()MAX(D

IVINIVOUTVINP •+•−=

For a typical scenario, VIN = 3.3V ± 5%, V

OUT

= 2.8V and

IO = 2.5A, therefore:

V

IN(MAX)

= 3.465V, V

OUT(MIN)

= 2.744V and I

Q(MAX)

= 1.75mA,

Thus P

D(MAX)

= 1.81W.

Using this figure, and assuming T

A(MAX)

= 85°C, we can
calculate the maximum thermal impedance allowable to
maintain TJ £ 150°C (see page 7):

Typical Characteristics (Cont.)

Quiescent Current vs.

Junction Temperature

Off-State Quiescent Current vs.

Junction Temperature

600

610

620

630

640

650

660

670

680

690

700

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

I

Q

(µA)

VIN = 3.3V

0

2

4

6

8

10

12

-50 -25 0 25 50 75 100 125 150

T

J

(°C)

I

Q(OFF)

(µA)

VIN = 5.5V

7ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

(

)

()

W/C33Rtherefore

,W/C0RandW/C3R

W/C36

81.1

85150

P

TT

R

)MAX)(AS(TH

)SC(TH)MAX)(CJ(TH

)MAX(D

)MAX(A)MAX(J

)MAX)(AJ(TH

°=

°=°=

°=

−

=

−

=

−

−−

−

Applications Information (Cont.)

This should be achievable for the TO-263 package using
pcb copper area to aid in conducting the heat away from
the device, such as a large (~2 squ. inch) pad connected
to the tab of the device. Internal ground/power planes
and air flow will also assist in removing heat. For higher
power dissipations it may be necessary to use a small
heatsink and the TO-220 package.

Outline Drawing - T0-263-3

Minimum Land Pattern - TO-263-3

8ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

Outline Drawing - TO-263-5

Minimum Land Pattern - TO-263-5

9ã 2001 Semtech Corp. www.semtech.com

SC1566

POWER MANAGEMENT

Semtech Corporation

Power Management Products Division

652 Mitchell Rd., Newbury Park, CA 91320

Phone: [phone] FAX [phone]

Contact Information

Outline Drawing - TO-220-3

Outline Drawing - TO-220-5