Datasheet L5972D Datasheet (SGS Thomson Microelectronics)

2A SWITCH STEP DOWN SWITCHING REGULATOR

■ 2A INTERNAL SWITCH

■ OPERATING INPUT VOLTAGE FROM 4.4V

TO 36V

■ OUTPUT VOLTAGE ADJUSTABLE FROM

1.235V TO 35V

■ LOW DROPOUT OPERATION: 100% DUTY

CYCLE

■ 250KHz INTERNALLY FIXED FREQUENCY

■ VOLTAGE FEEDFO RWA R D

■ ZERO LOAD CURRENT OPERATION

■ INTERNAL CURRENT LIMITING

■ PROTECTION AGAINST FEEDBACK

DISCONNECTION

■ THERMAL SHUTDOWN

APPLICATIONS:

■ CONSUMER: STB, DVD, TV, VCR,CAR

RADIO, LCD MONITORS

■ NETWORKING: XDSL, MODEMS,DC-DC

MODULES

■ COMPUTER: PRINTERS, AUDIO/GRAPHIC

CARDS, OPTICAL STORAGE, HARD DISK
DRIVE

■ INDUSTRIAL: CHARGERS, CAR BATTERY

DC-DC CONVERTERS

L5972D

SO8 (4+2+2)

ORDERING NUMBERS: L5972D (SO8)

L5972D013TR (Tape & Reel)

DESCRIPTION

The L5972D is a step down monolithic power switch­ing regulator with a minimum switch current limit of
2A so it is able to deliver more than 1.5A DC current
to the load depending on the application conditions.

The output voltage can be set from 1.235V to 35V.
The device uses an internal P-Channel D-MOS tran-

sistor (with a typical Rdson of 250m
element to minimize the s i ze of t he ext ernal c ompo­nents.

An internal oscillator fixes the switching frequency at
250KHz.

Having a minimum input voltage of 4.4V only, it is
particularly suitable for 5V bus, availabl e in all com­puter related applications.

Pulse by pulse current limit with the internal frequen­cy modulation offers an effective constant current
short circuit protection.

Ω

) as swi tch ing

TEST APPLICATION CIRCUIT

VIN = 4.4V to 35V

C1

10µF

35V

CERAMIC

May 2003

C4

22nF

C3

220pF

VCC OUT

COMP

R3

4.7K

8

4

6

L5972D

2

3

1

5

7

GND

D03IN1436

FB

L1 33µH

D1

STPS2L40U

R1

5.6K

R2

3.3K

VOUT=3.3V

C2

100µF

10V

1/10

L5972D

PIN CONNECTION

OUT
GND
GND

COMP

1
2
3
4

8
7
6
5

D02IN1367

VCC
GND
GND
FB

PIN DESCRIPT ION

N° Pin Function

1 OUT Regulator Output.

2,3,6,7 GND Ground.

4 COMP E/A output for frequency compensation.
5 FB Feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external

resistive divider is required for higher output voltages.

8 VCC Unregulated DC input voltage.

THERMAL DATA

Symbol Parameter Value Unit

R

th (j-amb)

(*) Package mounted on board (4cm2 ground-plane)

Thermal Resistance Junction to ambient Max. 65 (*) °C/W

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

Input Voltage 40 V

8

Out pin DC voltage

1

Out pin peak voltage at ∆t = 0.1µs
Maximum output current int. limit.
Analog pins 4 V

5

Power dissipation at Tamb ≤ 70°C 1.2 W
Operating junction temperature range -40 to 150 °C

j

Storage temperature range -55 to 150 °C

-1 to 40

-5 to 40

2/10

V
V

I

1

V4, V

P

tot

T

T

stg

V
V

L5972D

ELECTRICAL CHARACTERISTICS

(Tj = 25°C, VCC = 12V, unless otherwise specified.)

(*) Specification Referred to Tj from -40 to 125°C.

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

DYNAMIC CHARACTERISTICS (see test circuit ).

DC CHARACTERISTICS

I

Operating input voltage range Vo = 1.235V; Io = 1.5A * 4.4 36 V

CC

V

Dropout voltage VCC = 4.4V; Io = 1.5A * 0.375 0.75 V

d

I

Maximum limiting current VCC = 4.4V to 36V * 2 2.5 3 A

l

Switching frequency * 212 250 280 KHz

f

s

225 250 275 KHz

Duty cycle 0 100 %

Voltage feedback 4.4V < VCC < 36V,

V

5

20mA < IO < 1.5A

h Efficiency V

Total operating quiescent current * 3 5 mA

qop

I

Quiescent current Duty Cycle = 0; VFB = 1.5V 2.5 mA

q

= 5V, VCC = 12V 90 %

O

1.220 1.235 1.25 V

* 1.198 1.235 1.272 V

ERROR AMPLIFIER

V

V

I

o source

I

o sink

High level output voltage VFB = 1V 3.5 V

OH

Low level output voltage VFB = 1.5V 0.4 V

OL

Source output current V
Sink output current V

I

Source bias current 2.5 4 µA

b

DC open loop gain RL = ∞ 50 65 dB

gm Transconductance I

= 1.9V; VFB = 1V 200 300 µA

COMP

= 1.9V; VFB = 1.5V 1 1.5 mA

COMP

= -0.1mA to 0.1mA

comp

V

= 1.9V

COMP

2.3 mS

3/10

L5972D

(A)

Figure 1. Out put V ol t age v s. Junction

Temperature

Vo (V)

3.312

3.308

Vcc = 12V
Vo = 3.3V

3.304

3.3

Tj = 25°C

3.296

3.292

3.288

3.284

Tj = 125°C

3.28

3.276

00.511.5
Io

Figure 2. Line R egulation

Vo (V)

3.312

3.308

3.304

3.296

3.292

3.288

3.284

3.276

Vcc = 12V
Vo = 3.3V

3.3

3.28

010203040

Tj = 25°C

Tj = 125°C

Vcc (V)

Figure 3. Out put V ol t age v s. Junction

Temperature

Vo (V)

1.25

1.24

1.23

Figure 4. Quiescent Current vs. Junction

Iq (mA)

2

1.8

1.6
Vcc = 12V

1.4

1.2

-50

DC = 0%

050

Tj (°C)

100 150

Figure 5. Shutdown Curr ent vs. J un ct io n

Temperature

Ishd (µA)

70

60

50

40

30

-50

Vcc = 12V

0

50 100 150

Tj (°C)

Figure 6. Switching Frequency vs.Junction

Temperature

Iq (mA)

2

1.8

1.22
Vcc = 12V

1.21

Vcc=12V

1.2

-50 0 50 100 150
Tj (°C)

4/10

1.6

1.4

1.2

-50

Vcc = 12V
DC = 0%

050

Tj (°C)

100 150

L5972D

APPLICATION CIRCUIT

In figure 7 is shown the demo board application circuit for the device in SMD version, where the input supply
voltage, Vcc, can range from 4.4V to 25V due to the rated voltage of the input capacitor and the output voltage
is adjustable from 1.235V to V

Figure 7. Demo board Application Circuit

.

cc

VIN = 4.4V to 25V

C1

10µF

25V

CERAMIC

C4

22nF

C3

220pF

VCC OUT

COMP

R3

4.7K

8

4

6

L5972D

2

3

1

5

7

GND

D03IN1438

FB

L1 33µH

D1

STPS2L25U

Table 1. Component List

Reference Part Number Description Manufacturer

C1 10µF, 25V TOKIN
C2 POSCAP 10TPB100M 100µF, 10V Sanyo
C3 C1206C221J5GAC 220pF, 5%, 50V KEMET

R1

5.6K

R2

3.3K

VOUT=3.3V

C2

100µF

10V

C4 C1206C223K5RAC 22nF, 10%, 50V KEMET
R1 5.6K, 1%, 0.1W 0603 Neohm
R2 3.3K, 1%, 0.1W 0603 Neohm
R3 4.7K, 1%, 0.1W 0603 Neohm
D1 STPS2L25U 2A, 25V ST
L1 DO3316P-333 33µH, 2.1A COILCRAFT

5/10

L5972D

Figure 8. PC B lay o ut (c om po nent side)

Figure 9. PC B lay o ut (bot t om si de)

42mm

34mm

Figure 10. PC B layout (front si de)

Sideways two graphs show the Tj versus output current in different conditions of the input and output voltage.

6/10

L5972D

Figure 11. Junction Temperature vs. Output

Current

TJ(°C)

100.0

90.0

80.0

70.0

Vin=5V
Tamb.=25°C

Vo=2.5V

Vo=3.3V

Vo=1.8V

60.0

50.0

40.0

30.0

20.0

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Io(A)

Figure 12. Junction Temperature vs. Output

Current

TJ(°C)

100.0

90.0

80.0

Vin=12V

Tamb= 25°C

Vo=5V

70.0

60.0

50.0

40.0

30.0

20.0

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Io(A)

Vo=2.5V

Vo=3.3V

Figure 13. Efficiency vs. Output Current

95
93
91
89
87
85
83
81
79
77

Efficiency (%)

75
73
71
69
67

0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7

Vcc=5V

Vo=1.8V

Vo=1.8V

Vo=2.5V

Vo=2.5V

Vo=3.3V

Vo=3.3V

Io (A)

Figure 14. Efficiency vs. Output Current

96
94
92
90
88
86
84
82
80

Efficiency (%)

78
76
74
72
70

Vin=12V

Vin=12V

0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7

Vo=3.3V

Vo=3.3V

Vo=2.5V

Vo=2.5V

Vo=5V

Vo=5V

Io (A)

7/10

L5972D

APPLICATION IDEAS
Figure 15. Positive Buck-Boost regulator

VIN=5V

Vcc

8

C1
10uF
10V
Ceramic

C2
220pF

C3
22nF

R3

4.7k

COMP

L5972D

4

2

Figure 16. Buck-Boost regulator

VIN=5V

C1
10uF
10V
Ceramic

C2
10uF
25V
Ceramic

C3
220pF

Vcc

COMP

C4
22nF

R3

4.7k

6

GND

OUT

L1
33uH

D2
STPS2L25U

VOUT=12V/0.45A

1

D1
STPS2L25U

FB

5

3

7

M1
STN4NE03L

24k

2.7k

C4
100uF
16V

L1

OUT

8

L5972D

4

6

2

GND

1

FB

5

3

7

2.7k

24k

33uH

D1
STPS2L25U

C5
100uF
16V

VOUT=-12V/0.45A

Figure 17. Dua l ou t put v ol tage with auxili ary wi nding

8/10

VIN=12V

C1
10uF
25V

C2
220pF

C3
22nF

R3

4.7k

Vcc

COMP

8

L5972D

4

6

2

7

GND

OUT

1

FB

5

3

n=N1/N2=2

N2

N1

D1
STPS2L25U

D2
STPS2L25U

VOUT=3.3V

C4
100uF
10V

VOUT1=5V
50mA

C5
47uF
10V

L5972D

DIM.

D (1) 4.8 5.0 0.189 0.197

F (1) 3.8 4.0 0.15 0.157

(1) D and F do not include mold flash or protrusions. Mold flash or
potrusions shall not exceed 0.15mm (.006inch).

MIN. TYP. MAX. MIN. TYP. MAX.

A 1.75 0.069
a1 0.1 0.25 0.004 0.010
a2 1.65 0.065
a3 0.65 0.85 0.026 0.033

b 0.35 0.48 0.014 0.019
b1 0.19 0.25 0.007 0.010

C 0.25 0.5 0.010 0.020

c1 45° (typ.)

E 5.8 6.2 0.228 0.244

e 1.27 0.050
e3 3.81 0.150

L 0.4 1.27 0.016 0.050

M 0.6 0.024

S8° (max.)

mm inch

OUTLINE AND

MECHANICAL DATA

SO8

9/10

L5972D

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