LND34063A - Linear Dimensions Semiconductor

•

LND34063A

DATA

SHEET

GENERAL DESCRIPTION

• Operation from 3.0V to 40V Input

• Low Standby Current

• Current Limiting

• Output Switch Current to 1.5A

• Frequency Operation to 100kHz

• Precision 2% Reference

FEATURES

The LND34063A is a monolithic control circuit

containing the primary functions required for

DC-to-DC converters This device consist of an

internal temperature compensated reference,

comparator, controlled duty cycle oscillator

with an active current limit circuit, driver and

high current output switch. This device was

specifically designed to be incorporated in

Step-down and Step-up and Voltage-Inverting

applications with a minimum number of

external components.

DC-to-DC Converter Control Circuits

PIN CONNECTIONS

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

Switch

Collector

Switch

Emitter

Timing

Capacitor

Ground

Driver

Collector

pk

VCC

Comparator

Inverting

Input

I

Sense

LND34063A

Rating Symbol Value Unit

Power Supply Voltage Vcc 40 Vdc

Comparator Input Voltage Range VIR -0.3 to +40 Vdc

Switch Collector Voltage VC(Switch) 40 Vdc

Switch Emitter Voltage(Vpin=40V) VE(switch) 40 Vdc

Switch Collector to Emitter Voltage VCE(switch) 40 Vdc

Driver Collector Voltage Vc(driver) 40 Vdc

Driver Collector Current(Note 1) Ic(driver) 100 mA

Switch Current Isw 1.5 A

Operating Junction Temperature TJ+150 ºC

Operating Ambient Temperature TA0 to +70 ºC

Storage Temperature Tstg -65 to +150 ºC

ABSOLUTE MAXIMUM RATINGS

LND34063A

SCHEMATIC DIAGRAM

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

SQ

R

C

Ipk CT

Oscillator

1.25 V

Reference

+

-

O

OSwitch

Collector

Switch

Emitter

Timing

Capacitor

Comparator

Inverting

Input

VCC

Driver

Collector

I

Sense

pk

1

2

3

4

5

6

7

8

Ground

Q2

Q1

100

1

2

3

LND34063A

Vcc=5.0V,TA=Tlow to Thigh, unless otherwise specified.)

Characteristics Symbol Min Typ Max Unit

Oscillator

Frequency

(Vpin5=0V, CT=1.0nF, TA=25ºC) fOSC 24 33 42 kHz

Charge Current

(Vcc=5.0V to 40V, TA =25ºC) Ichg 24 35 42 µA

Discharge Current

(Vcc=5.0V to 40V, TA=25ºC Idischg 140 220 260 µA

Discharge to charge Current ratio

(Pin 7 to Vcc, TA =25ºC Idischg/Ichg 5.2 6.5 7.5 -

Current Limit Sense Voltage

(Ichg=I dischg, T=25ºC Vipk(sense) 250 300 350 mV

Output Switch(Note 2)

Saturation Voltage Darlington

Connection

(Isw=1.0 A, Pins 1,8 connected)

Vce(sat) -1.01.3V

Saturation Voltage, Darlington

Connection

(Isw=1.0A, Rpin8=82Ω to Vcc,

forcedβ=20)

Vce(sat) - 0.45 0.7 V

DC Current Gain

(Isw=1.0A, Vce=5.0V TA = 25º C hFE 50 75 - -

Collector Off-State Current

(Vce=40V)

Ic(off) - 40 100 µA

Comparator

Threshold Voltage

(TA=25ºC)

(TA=Tlow to Thigh)

Vth 1.225

1.21

1.25

-

1.275

1.29

V

Threshold Voltage Line Regulation

(Vcc=3.0V to 40V) Regline -1.45.0mV

Input Bias Current

(Vin=0V) IIB - -20 -400 nA

Total Device

Supply Current

(Vcc=5.0V to 40V, Ct=1.0nF,

Pin 7=Vcc,Vpin 5>Vth, Pin 2=Gnd,

remaining pins open)

Icc --4.0mA

Notes:

1. Maximum package power dissipation limits must be observed.

2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient

temperature as possible.

ELECTRICAL CHARACTERISTICS

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

LND34063A

SOME TYPICAL APPLICATIONS

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

SQ

R

C

Ipk CT

Oscillator

1.25 V

Reference

+

-

C

T

170 H

µ

R

sc

VINO

12 V

2

R

Co

O

VOUT

28V/175mA

1.0 H

µ

OOUT

V

Optional Filter

1

2

3

4

5

6

7

8

Fi

g

1 : STEP UP CONVERTER

1

R

Q2

Q1

100

1500pf

180

L

0.22

100

+

47k

330

+

100

+

2.2k

1

2

3

S

pk

+

C

Oscillator

-

I

Q

1.25 V

Reference

T

R

C

R

sc

VIN O

1

2

3

4

5

6

7

8

OO

O

OUT

V

O

R

8

5

3

V

C

I

6

1

R

pk

4

T

Oscillator

Q

IN

7

2

sc

+

-

S

1.25 V

Reference

OO

O

OUT

V

O

R

R --> 0 for

Co nst an t V IN

Fig 2 : External Boost Connections

for Ic Peak Greater than 1.5A

2a: External NPN Switch 2b: Ext ernal NPN Satura te d Swi tch

Q2

Q1

10 0

Q1

10 0

Q2

1

2

31

2

3

LND34063A

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

S

pk

+

C

Oscillator

-

I

Q

1.25 V

Reference

T

R

C

CT

R

sc

VINO

25 V

1

R

R2

Co

OOUT

V

5.0V/500mA

1.0 H

µ

OOUT

V

Optional Filter

1

2

3

4

5

6

7

8

Fi

g

3 : STEP DOWN CONVERTER

µ

220 H

Q2

Q1

100

470pf

0.33

100

+

1.2k

3.6k

470

+

100

+

L

1

2

3

O

R

8

5

3

V

C

I

6

1

R

pk

4

T

Oscillator

Q

IN

7

2

sc

+

-

S

1.25 V

Re feren ce

OO

OOUT

V

O

4a: External NPN Swi tch

OUT

+

7

I

CR

O

Q

6 3

V

2

pk

1.25 V

Re feren ce

-

T

81

O

sc

IN

C

V

O

Oscillator

5

S

4

R

4b: External NPN Saturated Switch

Fig4 : External Boost Connections

for Ic Peak Greater than 1.5A

Q1

100

Q2

Q1

Q2

100

1

2

3

1

2

3

LND34063A

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

2

OUT

O

IN

pk T

Oscillator

Optional Filter

o

sc

Q

8

5

OUT

1.0 H

2

1

C

+

-

3

1

V

O

V

1.25 V

Reference

Fi

g

5 : VOLTAGE INVERTING CONVERTER

6

µ

R

T

R

S

C

V

C

R

I

7

4

O

5.0V/500mA

R

25 V

C

220 H

µ

470

+

100

+

0.33

470pf

3.6k

Q2

Q1

1.2k

100

+

L

1

2

3

6a: External NP N Switch

OUT

+

7

I

CR

O

Q

6 3

V

2

pk

1.25 V

Reference

-

T

81

O

sc

IN

C

V

O

Oscillator

5

S

4

R

V

C

1.25 V

Reference

4

S

5

8

6

R

7

2

IN

Q

pk

1

O

-

R

3

OO

I

Oscillator

T

C

+

O

sc

6b: External NPN Satura ted Switch

OOUT

V

Fig6 : External Boost Connections

for Ic Peak Greater than 1.5A

Q1

Q2

100

Q1

Q2

100

1

2

31

2

3

LND34063A

Figure 7: Design Formula Table

Calculation Step-Up Step-down Voltage-Inverting

tON/tOFF (Vout+VF-VIN(min) ) / (VIN(min) -Vsat)(V

out+VF ) / (Vin(min) -Vsat -Vout)( V

out|+VF ) / (Vin -Vsat )

(tON/tOFF)

max 1/ f MIN 1/ f MIN 1/ f MIN

CT4.0 x 10-5 ton 4.0 x 10-5 ton 4.0 x 10-5 ton

IPK(switch) 2 Iout (max)(ton/toff + 1) 2 Iout(max) 2 Iout (max)(ton/toff + 1)

RSC 0.3 / Ipk(switch) 0.3 / Ipk(switch) 0.3 / Ipk(switch)

L(min) (Vin(min) –Vsat )/(Ipk(switch))=tout(max)

(Vin(min) – Vsat -Vout ) /

(Ipk(switch)) = tout(max)

(Vin(min) –Vsat ) / (Ipk(switch)) =

tout(max)

CO9(Ioutt

on) / (Vripple(pp))I

pk(switch) (ton + toff) / 8V ripple(pp) 9(Ioutt

on) / (Vripple(pp))

Terms and Definitions

Vsat-Saturation voltage of the output switch

VF –Forward voltage drop of the output rectifier.

The following power supply characteristics must be chosen:

VIN-Nominal input voltage

Vout-Desired output voltage, |Vout |=1.25 (1 +R2 / R1)

IOUT-Desired output current

fmin-Minmum desired output switching frequency at the selected values of VIN and IO

Vripple(p-p)- Desired peak-to-peak output ripple voltage. In pratice, the calculated capacitor value will need to be

increased due to its equivalent series resistance and board layout. The ripple voltage should be kept to a low value

since it will directly affect the line and load regulation.

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •