Analog Devices ADP3050 Datasheet

200 kHz, 1 A High-Voltage

a

FEATURES
Wide Input Voltage Range: 3.6 V to 30 V
Adjustable and Fixed (3.3 V, 5 V) Output Options
Integrated 1 A Power Switch
Uses Small Surface-Mount Components
Cycle-By-Cycle Current Limiting
Peak Input Voltage (100 ms): 60 V
Thermally Enhanced 8-Lead SOIC Package
Configurable as a Buck, Buck-Boost and SEPIC
Regulator

APPLICATIONS
Industrial Power Systems
PC Peripheral Power Systems
Preregulator for Linear Regulators
Distributed Power Systems
Automotive Systems
Battery Chargers

Step-Down Switching Regulator

ADP3050

FUNCTIONAL BLOCK DIAGRAM

GND

SD

FB

BIAS

2.5V

REGULATOR

FREQUENCY

AND CURRENT LIMIT

FOLDBACK

+

g

1.2V

m

200kHz

OSCILLATOR

CMP

CURRENT SENSE

AMPLIFIER

CURRENT

LIMIT

SQ DRIVER

R

ADP3050

IN

BOOST

SWITCH

GENERAL DESCRIPTION

The ADP3050 is a current-mode monolithic buck (step-down)
PWM switching regulator that contains a high current 1 A power
switch and all control, logic, and protection functions. It uses a
unique compensation scheme that allows the use of any type of
output capacitor (tantalum, ceramic, electrolytic, OS-CON).
Unlike some buck regulators, the design is not restricted to using
a specific type of output capacitor or ESR value.

A special boosted drive stage is used to saturate the NPN power
switch, providing a system efficiency higher than conventional
bipolar buck switchers. Further efficiency improvements are ob­tained by using the low voltage regulated output to provide the
device's internal operating current. A high switching frequency
allows the use of small external surface-mount components. A
wide variety of standard off-the-shelf devices can be used, pro­viding a great deal of design flexibility. A complete regulator
design requires only a few external components.

COMP

The ADP3050 includes a shutdown input that places the device
in a low-power mode, reducing the total supply current to under
20 µA. Internal protection features include thermal shutdown
circuitry and a cycle-by-cycle current-limit for the power switch
to provide complete device protection under fault conditions.

The ADP3050 provides excellent line and load regulation,
maintaining typically less than ±3% output voltage accuracy
over temperature and under all input voltage and output current
conditions.

The ADP3050 is specified over the industrial temperature range of
–40°C to +85°C and is available in a thermally enhanced 8-lead
SOIC package.

REV. 0

Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

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Fax: [phone] © Analog Devices, Inc., 2000

1

ADP3050–SPECIFICATIONS

Parameter Symbol Conditions Min Typ Max Unit

FEEDBACK

Feedback Voltage V
ADP3050 1.16 1.20 1.24 V
ADP3050-3.3 3.20 3.30 3.40 V
ADP3050-5 4.85 5.00 5.15 V

Line Regulation V

Load Regulation I

Input Bias Current I

ERROR AMPLIFIER

Transconductance

Voltage Gain

2

2

Output Current
ADP3050 COMP = 1.0 V, FB = 1.1 V to 1.3 V ±115 µA
ADP3050-3.3 COMP = 1.0 V, FB = 3.0 V to 3.6 V ±120 µA
ADP3050-5 COMP = 1.0 V, FB = 4.5 V to 5.5 V ±135 µA

OSCILLATOR

Oscillator Frequency

3

Minimum Duty Cycle D

Maximum Duty Cycle D

SWITCH

Average Output Current Limit4I
ADP3050 BOOST = 15 V, FB = 1.1 V 1.0 1.25 1.5 A
ADP3050-3.3 BOOST = 15 V, FB = 3.0 V 1.0 1.25 1.5 A
ADP3050-5 BOOST = 15 V, FB = 4.5 V 1.0 1.25 1.5 A

Peak Switch Current Limit

5

Saturation Voltage BOOST = 15 V, I

Leakage Current 50 nA

SHUTDOWN

Input Voltage Low 0.4 V

Input Voltage High 2.0 V

SUPPLY

Minimum Input Voltage

6

Minimum BIAS Voltage V

Minimum BOOST Voltage V

IN Supply Current I
Normal Mode BIAS = 5.0 V 0.7 1.5 mA
Shutdown Mode SD = 0 V, V

BIAS Supply Current I

BOOST Supply Current I

NOTES

1

All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC).

2

Transconductance and voltage gain measurements refer to the internal amplifier without the voltage divider. To calculate the transconductance and gain of the fixed

voltage parts, divide the values shown by FB/1.20.

3

The switching frequency is reduced when the feedback pin is lower than 0.8 ⫻ FB.

4

See Figure 22 for test circuit.

5

Switch current limit is measured with no diode, no inductor, and no output capacitor.

6

Minimum input voltage is not measured directly, but is guaranteed by other tests. The actual minimum input voltage needed to keep the output in regulation will

depend on output voltage and load current.

Specifications subject to change without notice.

FB

FB

g

m

A

VOL

f

OSC

MIN

MAX

CL(AVG)

I

CL(PEAK)

V

IN

BIAS

BOOST

Q

BIAS

BOOST

(VIN = 10 V, TA = –40ⴗC to +85ⴗC, unless otherwise noted)

Over Line and Temperature

= 10 V to 30 V, no load 0.005 %/V

IN

= 100 mA to 1 A,

LOAD

ADP3050AR Only –1.0 +0.1 +1.0 %/A
ADP3050AR-3.3, ADP3050AR-5 –0.5 +0.1 +0.5 %/A
ADP3050AR Only 0.65 2 µA

1250 µMho
300 V/V

170 200 240 kHz

10 %
90 %

1.5 1.7 2.1 A

= 1 A 0.65 0.95 V

LOAD

3.6 V

3.0 V

3.0 V

≤ 30 V 15 40 µA

IN

BIAS = 5.0 V 4.0 6.0 mA
BOOST = 15 V, ISW = 0.5 A 18 mA
BOOST = 15 V, ISW = 1.0 A 20 40 mA

–2–

REV. 0

ADP3050

ABSOLUTE MAXIMUM RATINGS*

IN Voltage

Steady State . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +30 V

Peak (<100 ms) . . . . . . . . . . . . . . . . . . . . . –0.3 V to +60 V

BOOST Voltage

Steady State . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +45 V

Peak (<100 ms) . . . . . . . . . . . . . . . . . . . . . –0.3 V to +65 V

SD, BIAS Voltage . . . . . . . . . . . . . . . . . –0.3 V to IN + 0.3 V

FB Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +8 V

COMP Voltage . . . . . . . . . . . . . . . . . . . –0.3 V to IN + 0.3 V

SWITCH Voltage . . . . . . . . . . . . . . . . . –0.3 V to IN + 0.3 V

Operating Ambient Temperature Range . . . . –40°C to +85°C

Operating Junction Temperature Range . . . –40°C to +125°C

Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C

(2-Layer PCB) . . . . . . . . . . . . . . . . . . . . . . . . . . 108°C/W

θ

JA

(4-Layer PCB) . . . . . . . . . . . . . . . . . . . . . . . . . . . 81°C/W

θ

JA

Lead Temperature Range (Soldering, 60 sec.) . . . . . . . . 300°C

*This is a stress rating only; operation beyond these limits can cause the device to

be permanently damaged. Unless otherwise specified, all voltages are referenced
to GND

ORDERING GUIDE

Output Temperature

Model Voltage Range Package*

°

ADP3050AR ADJ –40
ADP3050AR-3.3 3.3 V –40

C to +85°C SO-8

°

C to +85°C SO-8

ADP3050AR-5 5.0 V –40°C to +85°C SO-8

*SO = Small Outline Package

PIN CONFIGURATION

8-Lead SOIC

(R-Suffix)

SWITCH

BOOST

BIAS

FB

1

ADP3050

2

TOP VIEW

3

(Not to Scale)

4

8

7

6

5

IN

GND

SD

COMP

PIN FUNCTION DESCRIPTION

Pin Name Function

1 SWITCH This is the emitter of the internal NPN

power switch. The voltage at this pin switches
between V

and approximately –0.5 V.

IN

2 BOOST This pin is used to provide a boosted voltage

(higher than V

) for the drive stage of the

IN

NPN power switch. With the higher drive
voltage, the power switch can be saturated,
greatly reducing the switch power losses.

3 BIAS Connect this pin to the regulated output

voltage to maximize system efficiency.
When this pin is above 2.7 V, most of the
ADP3050 operating current will be taken
from the output instead of the input supply.
Leave unconnected if not used.

4 FB This feedback pin senses the regulated output

voltage. Connect this pin directly to the out­put (fixed output versions).

5 COMP This pin is used to compensate the regulator

with an external resistor and capacitor. This
pin can be used to override the control loop,
but the voltage on this pin should not exceed
about 2 V, as the pin is internally clamped to
ensure a fast transient response. Use a pull-up
resistor if this pin is to be pulled higher than 2 V.

6 SD Use this pin to turn the device on and off. If

this feature is not needed, tie this pin directly

.

to V

IN

7 GND Connect this pin to local ground plane.
8 IN Connect this pin to the input supply voltage.

An input bypass capacitor must be placed
close to this pin to ensure proper regulator
operation.

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although this device features proprietary ESD protection circuitry, permanent damage may occur
on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.

REV. 0

–3–

ADP3050

– Typical Characteristics

5.0
VIN = 10V, NO LOAD

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

QUIESCENT OPERATING CURRENT – mA

0.5

0

ⴚ4585ⴚ35

INTO BIAS PIN

INTO VIN PIN

ⴚ25 ⴚ15 ⴚ5

5 152535455565 75

TEMPERATURE – ⴗC

Figure 1. Quiescent Operating Current vs. Temperature

25

20

15

2.0
VIN = 10V

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

AVERAGE OUTPUT CURRENT – A

0.2

0

ⴚ25 ⴚ15 ⴚ5

ⴚ4585ⴚ35

5 152535455565 75

TEMPERATURE – ⴗC

Figure 4. Average Output Current Limit vs. Temperature

25

VIN = 10V

20

15

10

5

SHUTDOWN QUIESCENT CURRENT – ␮A

0

030

10 15 20 25

5

SUPPLY VOLTAGE – V

Figure 2. Shutdown Quiescent Current vs. Supply Voltage

10

BIAS TIED TO V

8

6

4

2

QUIESCENT OPERATING CURRENT – mA

0

030

OUT

V

OUT

V

= 3.3V

OUT

10 15 20 25

5

SUPPLY VOLTAGE – V

= 5V

Figure 3. Quiescent Operating Current vs. Supply Voltage

10

BOOST CURRENT – mA

5

0

0

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
LOAD CURRENT – A

Figure 5. Boost Current vs. Load Current

100

90

80

70

60

50

40

EFFICIENCY – %

30

20

10

0

01k200 400 600 800

VIN = 6V

VIN = 24V

= 12V

V

IN

VIN = 18V

L = 33␮H
C

IN

C

OUT

VIN = 30V

= 22␮F

= 100␮F

OUTPUT CURRENT – mA

Figure 6. 5 V Output Efficiency

1.00.1

–4–

REV. 0

ADP3050

INPUT VOLTAGE – V

0

OUTPUT VOLTAGE CHANGE – %

10 20 30

0.6

0.2

0.4

0

ⴚ0.6

ⴚ0.4

ⴚ0.2

V

OUT

= 3.3V

I

LOAD

= 1A

I

LOAD

= 100mA

100

90

80

70

60

50

40

EFFICIENCY – %

30

20

10

0

01k200 400 600 800

= 5V

V

IN

VIN = 12V

VIN = 24V

VIN = 18V

L = 33␮H
C

= 22␮F

IN

= 100␮F

C

OUT

OUTPUT CURRENT – mA

V

IN

= 30V

Figure 7. 3.3 V Output Efficiency

0.5

VIN = 10V

ⴚ0.1

ⴚ0.2

ⴚ0.3

OUTPUT VOLTAGE CHANGE – %

ⴚ0.4

ⴚ0.5

0.4

0.3

0.2

0.1

I

LOAD

0

ⴚ4585ⴚ35

= 1A

ⴚ25 ⴚ15 ⴚ5

5 152535455565 75

TEMPERATURE – ⴗC

Figure 8. Output Voltage Change vs. Temperature

Figure 10. 3.3 V Output Voltage Change vs. Input Voltage

8

7

V

= 5V

6

5

4

MINIMUM INPUT VOLTAGE – V

3

2
0

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

OUT

V

= 3.3V

OUT

LOAD CURRENT – A

1.00.1

Figure 11. Minimum Input Voltage vs. Load Current

ⴚ0.02

ⴚ0.04

ⴚ0.06

ⴚ0.08

ⴚ0.10

ⴚ0.12

ⴚ0.14

OUTPUT VOLTAGE CHANGE – %

ⴚ0.16

ⴚ0.18

0

VIN = 10V

01.00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
LOAD CURRENT – A

Figure 12. Load Regulation

0.6

V

= 5V

OUT

0.4

0.2

I

= 1A

0.0

ⴚ0.2

OUTPUT VOLTAGE CHANGE – %

ⴚ0.4

ⴚ0.6

0

LOAD

I

= 100mA

LOAD

10

INPUT VOLTAGE – V

20 30

Figure 9. 5 V Output Voltage Change vs. Input Voltage

REV. 0

–5–