Datasheet ADP1073 Datasheet (Analog Devices)

Micropower DC–DC Converter

SET

V

IN

GAIN BLOCK/
ERROR AMP

COMPARATOR

SW2

FBGND

SW1

AO

I

LIM

OSCILLATOR

DRIVER

A1

A2

212mV

REFERENCE

ADP1073

a

Adjustable and Fixed 3.3 V, 5 V, 12 V

FEATURES
Operates at Supply Voltages from 1.0 V to 30 V
Ground Current 100 mA
Works in Step-Up or Step-Down Mode
Very Few External Components Required
Low Battery Detector On-Chip
User-Adjustable Current Limit
Internal 1 A Power Switch
Fixed and Adjustable Output Voltage Versions
8-Lead DIP or SO-8 Package

APPLICATIONS
Single-Cell to 5 V Converters
Laptop and Palmtop Computers
Pagers
Cameras
Battery Backup Supplies
Cellular Telephones
Portable Instruments
4 mA–20 mA Loop Powered Instruments
Hand-Held Inventory Computers

GENERAL DESCRIPTION

The ADP1073 is part of a family of step-up/step-down switch­ing regulators that operates from an input supply voltage of as
little as 1.0 V. This extremely low input voltage allows the
ADP1073 to be used in applications requiring use of a single
cell battery as the primary power source.

The ADP1073 can be configured to operate in either step-up or
step-down mode but for input voltages greater than 3 V, the
ADP1173 is recommended.

An auxiliary gain amplifier can serve as a low battery detector or
linear regulator. Quiescent current on the ADP1073-5 is only
100 µA unloaded, making it ideal for systems where long battery
life is required.

The ADP1073 can deliver 40 mA at 5 V from an input voltage
range as low as 1.25 V, or 10 mA at 5 V from a 1.0 V input.

Current limiting is available by adding an external resistor.

V

IN

ADP1073

FUNCTIONAL BLOCK DIAGRAMS

ADP1073

SET

ADP1073-3.3
ADP1073-5
ADP1073-12

OSCILLATOR

ADP1073-3.3: R1 = 62.1kV
ADP1073-5: R1 = 40kV
ADP1073-12: R1 = 16.3kV

212mV

REFERENCE

A2

GAIN BLOCK/
ERROR AMP

A1

R1

COMPARATOR

R2

904kV

ADP1073-3.3, 5, 12

SENSEGND

DRIVER

AO

I

LIM

SW1

SW2

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., 1997

ADP1073–SPECIFICATIONS

(@ TA = 08C to +708C, VIN = 1.5 V unless otherwise noted)

Parameter Conditions Symbol Min Typ Max Units

QUIESCENT CURRENT Switch Off I

QUIESCENT CURRENT, STEP-UP No Load, ADP1073-3.3 I

Q

Q

100 165 µA
100 µA

MODE CONFIGURATION ADP1073-5 100 µA

ADP1073-12, T

INPUT VOLTAGE Step-Up Mode V

Step-Up Mode, T

= +25°C 100 µA

A

= +25°C 1.0 12.6 V

A

IN

1.15 12.6 V

Step-Down Mode 30 V

COMPARATOR TRIP POINT VOLTAGE ADP1073

OUTPUT SENSE VOLTAGE ADP1073-3.3

ADP1073-5
ADP1073-12

1

2

2

2

V

OUT

200 212 222 mV

3.14 3.30 3.47 V

4.75 5.00 5.25 V

11.4 12.00 12.6 V

COMPARATOR HYSTERESIS ADP1073 5 10 mV

OUTPUT HYSTERESIS ADP1073-3.3 90 130 mV

ADP1073-5 125 250 mV
ADP1073-12 300 600 mV

OSCILLATOR FREQUENCY f

MAXIMUM DUTY CYCLE Full Load (V

FB

< V

) DC 577280 %

REF

SWITCH ON TIME t

FEEDBACK PIN BIAS CURRENT ADP1073 VFB = 0 V I

SET PIN BIAS CURRENT V

AO OUTPUT LOW I
REFERENCE LINE REGULATION 1.0 V ≤ V

SWITCH SATURATION VOLTAGE V

STEP-UP MODE T

A2 ERROR AMP GAIN R

REVERSE BATTERY CURRENT

4

CURRENT LIMIT 220 Ω Between I

= V

SET

REF

= 100 µAV

AO

≤ 1.5 V 0.35 %/V

1.5 V ≤ V

IN
MIN

V

IN

T

MIN

V

IN

T

MIN

L

T

A

T

A

IN

≤ 12 V 0.05 0.15 %/V

IN

= 1.5 V, I

to T

= 1.5 V, I

to T

= 5 V, I

to T

= 100 kΩ

= 400 mA, +25°CV

SW

MAX

= 500 mA, +25°C 400 550 mV

SW

MAX

= 1 A, +25°C 700 1000 mV

SW

MAX

3

= +25°CI

and V

LIM

IN

= +25°CI

OSC

ON

FB

I

SET

AO

CESAT

A

V

REV

LIM

14 19 24 kHz

28 38 50 µs

60 300 nA

100 220 nA

0.15 0.4 V

300 450 mV

600 mV

750 mV

1500 mV

400 1000 V/V

750 mA

400 mA

CURRENT LIMIT TEMPERATURE

COEFFICIENT –0.3 %/°C

SWITCH-OFF LEAKAGE CURRENT Measured at SW1 Pin

T

= +25°CI

A

MAXIMUM EXCURSION BELOW GND I

NOTES

1

This specification guarantees that both the high and low trip point of the comparator fall within the 200 mV to 222 mV range.

2

This specification guarantees that the output voltage of the fixed versions will always fall within the specified range. The waveform at the sense pin will exhibit a
sawtooth shape due to the comparator hysteresis.

3

100 kΩ resistor connected between a 5 V source and the AO pin.

4

The ADP1073 is guaranteed to withstand continuous application of +1.6 V applied to the GND and SW2 pins while VIN, I

All limits at temperature extremes are guaranteed via correlation using standard Quality Control methods.
Specifications subject to change without notice.

≤ 10 µA, Switch Off

SW1

T

= +25°CV

A

LEAK

SW2

LIM

–2–

115µA

–400 –350 mV

and SW1 pins are grounded.

REV. 0

ADP1073

1
2
3
4

8
7
6
5

TOP VIEW

(Not to Scale)

ADP1073

I

LIM

V

IN

SW1
SW2

FB (SENSE)*
SET
AO
GND

* FIXED VERSIONS

1
2
3
4

8
7
6
5

TOP VIEW

(Not to Scale)

ADP1073

I

LIM

V

IN

SW1
SW2

FB (SENSE)*
SET
AO
GND

* FIXED VERSIONS

ABSOLUTE MAXIMUM RATINGS

Input Supply Voltage, Step-Up Mode . . . . . . . . . . . . . . . 15 V

Input Supply Voltage, Step-Down Mode . . . . . . . . . . . . . 36 V

SW1 Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 V

SW2 Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . .–0.4 V to V

IN

Feedback Pin Voltage (ADP1073) . . . . . . . . . . . . . . . . . . . 5 V

Switch Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 A

Maximum Power Dissipation . . . . . . . . . . . . . . . . . . 500 mW

Operating Temperature Range (A) . . . . . . . . . . 0°C to +70°C

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

Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . .+300°C

CADDELL-BURNS

7200-12

82mH

I

V

LIM

IN

1.5V

AA CELL*

OPERATES WITH CELL VOLTAGE
*ADD 10mF DECOUPLING CAPACITOR IF BATTERY

IS MORE THAN 2 INCHES AWAY FROM ADP1073

ADP1073-5

GND

SW1

SENSE

SW2

1N5818

$1.0V

+5V
40mA

100mF
SANYO
OS-CON

Figure 1. Typical Application

ORDERING GUIDE

Output Package

Model* Voltage Options**

ADP1073AN ADJ N-8
ADP1073AR ADJ SO-8
ADP1073AN-3.3 3.3 V N-8
ADP1073AR-3.3 3.3 V SO-8
ADP1073AN-5 5 V N-8
ADP1073AR-5 5 V SO-8
ADP1073AN-12 12 V N-8
ADP1073AR-12 12 V SO-8

NOTES

**Temperature Range: 0°C to +70°C.

**N = Plastic DIP; SO = Small Outline Package.

PIN FUNCTION DESCRIPTIONS

Pin Mnemonic Function

1I

LIM

For normal conditions this pin is con­nected to V

. When a lower current

IN

limit is required, a resistor should be
connected between I

LIM

and V

IN.

Limit-

ing the switch current to 400 mA is
achieved by connecting a 220 Ω resistor.

2V

IN

Input Voltage.

3 SW1 Collector Node of Power Transistor.

For step-down configuration, connect to

for step-up configuration, connect

V

IN;

to an inductor/diode.

4 SW2 Emitter Node of Power Transistor. For

step- down configuration, connect to
inductor/diode; for step-up configura­tion, connect to ground. Do not allow
this pin to drop more than a diode drop

below ground.
5 GND Ground.
6 AO Auxiliary Gain (GB) Output. The open

collector can sink 100 µA.
7 SET Gain Amplifier Input. The amplifier’s

positive input is connected to the SET

pin and its negative input is connected

to the 212 mV reference.
8 FB/SENSE On the ADP1073 (adjustable) version

this pin is connected to the comparator

input. On the ADP1073-3.3, ADP1073-

5 and ADP1073-12, the pin goes di-

rectly to the internal application resistor

that sets output voltage.

PIN CONFIGURATIONS

8-Lead Plastic DIP 8-Lead Small Outline Package
(N-8) (SO-8)

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 the ADP1073 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–

WARNING!

ESD SENSITIVE DEVICE

ADP1073

TEMPERATURE – 8C

34.5

30

240

085

25 70

32

31.5
31

30.5

34

33.5
33

32.5

SWITCH-ON TIME – ms

–Typical Performance Characteristics

1.2

1

0.8

Volts

0.6
(SAT) –
CE

0.4

V

0.2

VIN = 5.0V

V

= 3.0V

IN

VIN = 1.0V

0

0.1 0.2 1.20.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1
SWITCH CURRENT – Amps

V

IN

= 1.25V

VIN = 1.5V

V

IN

= 2.0V

Figure 2. Saturation Voltage vs.
Switch Current in Step-Up Mode

1000

100

FOR VIN > 1.6V,
R

= 68V

10

OUTPUT CURRENT – mA

0

1 3.5

1.5 2 2.5 3
INPUT VOLTAGE – Volts

LIM

Figure 5. Guaranteed Minimum
Output Current at V

= 5 V vs.

OUT

Input Voltage

2

1.8
SATURATION VOLTAGE

1.6

1.4

1.2

1

0.8

0.6

0.4

SWITCH ON VOLTAGE – Volts

0.2

0

0.05

0.2 0.3 0.4 0.5 0.6

0.1 0.7

SWITCH CURRENT – Amps

Figure 3. Switch ON Voltage vs.
Switch Current in Step-Down Mode

120

110

100

90

80

70

60

SET PIN BIAS CURRENT – nA

50

40

240

085

25 70

TEMPERATURE – 8C

Figure 6. Set Pin Bias Current vs.
Temperature

1400

1200

800

600

400

200

0

10 100030

VIN = 3V
WITH L = 82mH

VIN = 1.5V
WITH L = 82mH

50

70 90 200 400 600 800

1000

SWITCH CURRENT – mA

VIN = 12V
WITH L = 150mH

R

– V

LIM

Figure 4. Maximum Switch Current
vs. R

LIM

160

140

120

100

SUPPLY CURRENT – mA

VIN = 1.5V

80

60

40

240

085

25 70

TEMPERATURE – 8C

Figure 7. Supply Current vs.
Temperature

22

21

20

19

18

17

16

15

OSCILLATOR FREQUENCY – kHz

14

240

08525 70

TEMPERATURE – 8C

Figure 8. Oscillator Frequency vs.
Temperature

70

68

66

64

62

60

DUTY CYCLE – %

58

56

240

085

25 70

TEMPERATURE – 8C

Figure 9. Duty Cycle vs. Temperature

–4–

Figure 10. Switch ON Time vs.
Temperature

REV. 0

2300

ADP1073

2100

1900

1700

1500

GAIN BLOCK GAIN – V/V

1300

1100

240

085

TEMPERATURE – 8C

Figure 11. “Gain Block” Gain vs. Temperature

THEORY OF OPERATION

The ADP1073 is a flexible, low power switch mode power
supply (SMPS) controller. The regulated output voltage can be
greater than the input voltage (boost or step-up mode) or less
than the input (buck or step-down mode). This device uses a
gated-oscillator technique to provide very high performance
with low quiescent current.

A functional block diagram of the ADP1073 is shown on the
front page. The internal 212 mV reference is connected to one
input of the comparator, while the other input is externally
connected (via the FB pin) to a feedback network connected to
the regulated output. When the voltage at the FB pin falls below
212 mV, the 19 kHz oscillator turns on. A driver amplifier pro­vides base drive to the internal power switch and the switching
action raises the output voltage. When the voltage at the FB pin
exceeds 212 mV, the oscillator is shut off. While the oscillator is
off, the ADP1073 quiescent current is only 100 µA. The com-
parator includes a small amount of hysteresis, which ensures
loop stability without requiring external components for fre­quency compensation.

The maximum current in the internal power switch can be set
by connecting a resistor between V

IN

and the I

pin. When

LIM

the maximum current is exceeded, the switch is turned OFF.
The current limit circuitry has a time delay of about 2 µs. If an
external resistor is not used, connect I
mation on I

is included in the Limiting the Switch Current

LIM

to VIN. Further infor-

LIM

section of this data sheet.
The ADP1073 internal oscillator provides 38 µs ON and 15 µs

OFF times, which is ideal for applications where the ratio be­tween V

and V

IN

is roughly a factor of three (such as gener-

OUT

ating +5 V from a single 1.5 V cell). Wider range conversions,
as well as step-down converters, can also be accomplished with
a slight loss in the maximum output power that can be obtained.

VIN = 1.5V

= 100kV

R

L

25 70

An uncommitted gain block on the ADP1073 can be connected
as a low-battery detector, linear post-regulator or undervoltage
lockout detector. The inverting input of the gain block is inter­nally connected to the 212 mV reference. The noninverting
input is available at the SET pin. A resistor divider, connected
between V

and GND with the junction connected to the SET

IN

pin, causes the AO output to go LOW when the input voltage
goes below the low battery set point. The AO output is an open
collector NPN transistor that can sink 100 µA.

The ADP1073 provides external connections for both the col­lector and emitter of its internal power switch, which permits
both step-up and step-down modes of operation. For the step­up mode, the emitter (Pin SW2) is connected to GND and the
collector (Pin SW1) drives the inductor. For step-down mode,
the emitter drives the inductor while the collector is connected

.

to V

IN

The output voltage of the ADP1073 is set with two external
resistors. Three fixed-voltage models are also available:
ADP1073-3.3 (+3.3 V), ADP1073-5 (+5 V) and ADP1073-12
(+12 V). The fixed-voltage models are identical to the ADP1073,
except that laser-trimmed voltage-setting resistors are included
on the chip. Only three external components are required to
form a +3.3 V, +5 V or +12 V converter. On the fixed-voltage
models of the ADP1073, simply connect the feedback pin (Pin

8) directly to the output voltage.
The ADP1073 oscillator only turns on when the output voltage

is below the programmed voltage. When the output voltage is
above the programmed voltage, the ADP1073 remains in its
quiescent state to conserve power. Output ripple, which is in­herent in gated oscillator converters, is typically 125 mV for a
5 V output and 300 mV for a 12 V output. This ripple voltage
can be greatly reduced by inserting the gain-block between the
output and the FB pin. Further information and a typical circuit
are shown in the Programming the Gain Block section.

REV. 0

–5–

ADP1073

COMPONENT SELECTION
General Notes on Inductor Selection

When the ADP1073 internal power switch turns on, current
begins to flow in the inductor. Energy is stored in the inductor
core while the switch is on, and this stored energy is then trans­ferred to the load when the switch turns off. Both the collector
and the emitter of the switch transistor are accessible on the
ADP1073, so the output voltage can be higher, lower or of
opposite polarity than the input voltage.

To specify an inductor for the ADP1073, the proper values of
inductance, saturation current and dc resistance must be deter­mined. This process is not difficult, and specific equations for
each circuit configuration are provided in this data sheet.
In general terms, however, the inductance value must be low
enough to store the required amount of energy (when both
input voltage and switch ON time are at a minimum) but high
enough that the inductor will not saturate when both V

IN

and
switch ON time are at their maximum values. The inductor
must also store enough energy to supply the load without satu­rating. Finally, the dc resistance of the inductor should be low
so that excessive power will not be wasted by heating the
windings. For most ADP1073 applications, an 82 µH to
1000 µH inductor with a saturation current rating of 300 mA to
1 A is suitable. Ferrite core inductors that meet these specifica­tions are available in small, surface-mount packages.

To minimize Electro-Magnetic Interference (EMI), a toroid or
pot core type inductor is recommended. Rod core inductors are
a lower cost alternative if EMI is not a problem.

Calculating the Inductor Value

Selecting the proper inductor value is a simple three-step process:

1. Define the operating parameters: minimum input voltage,

maximum input voltage, output voltage and output current.

2. Select the appropriate conversion topology (step-up, step-

down or inverting).

3. Calculate the inductor value, using the equations in the

following sections.

Inductor Selection—Step-Up Converter

In a step-up, or boost, converter (Figure 15), the inductor must
store enough power to make up the difference between the
input voltage and the output voltage. The power that must be
stored is calculated from the equation:

where L is in henrys and R' is the sum of the switch equivalent
resistance (typically 0.8 Ω at +25°C) and the dc resistance of
the inductor. If the voltage drop across the switch is small com­pared to V

, a simpler equation can be used:

IN

V

(t)=

IN

t

L

I

L

(4)

Replacing t in the above equation with the ON time of the ADP1073
(38 µs, typical) will define the peak current for a given inductor
value and input voltage. At this point, the inductor energy can
be calculated as follows:

1

E

=

L

As previously mentioned, E

2

L × I

2

PEAK

must be greater than PL/f

L

OSC

(5)

so the
ADP1073 can deliver the necessary power to the load. For best
efficiency, peak current should be limited to 1 A or less. Higher
switch currents will reduce efficiency because of increased satu­ration voltage in the switch. High peak current also increases
output ripple. As a general rule, keep peak current as low as
possible to minimize losses in the switch, inductor and diode.

In practice, the inductor value is easily selected using the equa­tions above. For example, consider a supply that will generate
5 V at 25 mA from two alkaline batteries with a 2 V end-of-life
voltage. The inductor power required is, from Equation 1:

P

=(5V +0.5V –2V)×(25 mA) =87.5mW

L

On each switching cycle, the inductor must supply:

P

87.5mW

L

=

f

19 kHz

OSC

= 4.6 µ

J

Since the inductor power is low, the peak current can also be
low. Assuming a peak current of 100 mA as a starting point,
Equation 4 can be rearranged to recommend an inductor value:

L =

V

IN

I

L(MAX )

t =

2V

100 mA

38 µs = 760 µH

Substituting a standard inductor value of 470 µH, with 1.2 Ω dc
resistance, will produce a peak switch current of:

–2.0 Ω×38 µs

I

PEAK

=

2V

2.0 Ω



1–e







470 µH



=149 mA







Once the peak current is known, the inductor energy can be
calculated from Equation 5:

where V

= V

()

L

is the diode forward voltage (≈ 0.5 V for a 1N5818

D

OUT+VD–VIN( MIN)

×I

()

OUT

(1)

P

Schottky). Energy is only stored in the inductor while the
ADP1073 switch is ON, so the energy stored in the inductor on
each switching cycle must be must be equal to or greater than:

L

f

OSC

(2)

P

in order for the ADP1073 to regulate the output voltage.
When the internal power switch turns ON, current flow in the

inductor increases at the rate of:

–R′t

L

(t)=

R′

IN





I



V

1–e



L





(3)

–6–

1

E

=

(470 µH )×(149 mA)2=5.2 µJ

L

2

The inductor energy of 5.2 µJ is greater than the P

L/fOSC

re­quirement of 4.6 µJ, so the 470 µH inductor will work in this
application. The optimum inductor value can be determined
by substituting other inductor values into the same equations.
When selecting an inductor, the peak current must not exceed
the maximum switch current of 1.5 A.

The peak current must be evaluated for both minimum and
maximum values of input voltage. If the switch current is high
when V
at the maximum value of V

is at its minimum, then the 1.5 A limit may be exceeded

IN

. In this case, the ADP1073’s current

IN

REV. 0

ADP1073

limit feature can be used to limit switch current. Simply select a
resistor (using Figure 4) that will limit the maximum switch
current to the I

. This will improve efficiency by producing a constant I

V

IN

value calculated for the minimum value of

PEAK

PEAK

as VIN increases. See the Limiting the Switch Current section of
this data sheet for more information.

Note that the switch current limit feature does not protect the
circuit if the output is shorted to ground. In this case, current is
limited only by the dc resistance of the inductor and the forward
voltage of the diode.

Inductor Selection—Step-Down Converter

The step-down mode of operation is shown in Figure 16. Unlike
the step-up mode, the ADP1073’s power switch does not satu­rate when operating in the step-down mode. Switch current
should therefore be limited to 600 mA for best performance in
this mode. If the input voltage will vary over a wide range, the

pin can be used to limit the maximum switch current.

I

LIM

The first step in selecting the step-down inductor is to calculate
the peak switch current as follows:

I

PEAK

=

2×I

DC

OUT



V



VIN–V



OUT+VD

SW+VD






(6)

where DC = duty cycle (0.72 for the ADP1073)

VSW = voltage drop across the switch

= diode drop (0.5 V for a 1N5818)

V

D

= output current

I

OUT

= the output voltage

V

OUT

= the minimum input voltage

V

IN

As previously mentioned, the switch voltage is higher in step­down mode than in step-up mode. V
current and is therefore a function of V
For most applications, a V

value of 1.5 V is recommended.

SW

is a function of switch

SW

, L, time and V

IN

OUT

.

The inductor value can now be calculated:

where t

L =

= switch ON time (38 µs)

ON

I

PEAK

×t

ON

(7)

V

IN(MIN )–VSW–VOUT

If the input voltage will vary (such as an application which must
operate from a battery), an R
from Figure 4. The R

LIM

resistor should be selected

LIM

resistor will keep switch current con-

stant as the input voltage rises. Note that there are separate

values for step-up and step-down modes of operation.

R

LIM

For example, assume that +3.3 V at 150 mA is required from a
9 V battery with a 6 V end-of-life voltage. Deriving the peak
current from Equation 6 yields:

I

PEAK

2 ×150 mA

=

0.72



3.3 + 0.5



6–1.5+0.5





= 317 mA





The peak current can than be inserted into Equation 7 to calcu­late the inductor value:

L =

317 mA

×38 µs =144 µH

6–1.5–3.3

Since 144 µH is not a standard value, the next lower standard
value of 100 µH would be specified.

To avoid exceeding the maximum switch current when the
input voltage is at +9 V, an R

resistor should be specified.

LIM

Inductor Selection—Positive-to-Negative Converter

The configuration for a positive-to-negative converter using the
ADP1073 is shown in Figure 17. As with the step-up converter,
all of the output power for the inverting circuit must be supplied
by the inductor. The required inductor power is derived from
the formula:

= |V

L

|+V

()

OUT

×I

()

D

OUT

(8)

P

The ADP1073 power switch does not saturate in positive-to­negative mode. The voltage drop across the switch can be
modeled as a 0.75 V base-emitter diode in series with a 0.65 Ω
resistor. When the switch turns on, inductor current will rise at
a rate determined by:

I

(t) =

L

where R' = 0.65 Ω + R

V

L

R'

L(DC)






1–e



L





(9)

–R't

VL = VIN – 0.75 V

For example, assume that a –5 V output at 75 mA is to be gen­erated from a +4.5 V to +5.5 V source. The power in the induc­tor is calculated from Equation 8:

= |−5V|+0.5V

()

L

×(75mA) =413 mW

P

During each switching cycle, the inductor must supply the fol­lowing energy:

P

413 mW

L

=

f

19 kHz

OSC

=21.7µ

J

Using a standard inductor value of 330 µH, with 1 Ω dc resis-
tance, will produce a peak switch current of:

–1.65 Ω×38 µs

I

PEAK

4.5V –0.75V

=

0.65 Ω+1Ω



1–e




330 µH



=393 mA




Once the peak current is known, the inductor energy can be
calculated from Equation 9:

1

E

=

(330 µH ) ×(393 mA)2=25.5 µJ

L

2

The inductor energy of 25.5 µJ is greater than the P

L/fOSC

requirement of 21.7 µJ, so the 330 µH inductor will work in this
application.

The input voltage varies between only 4.5 V and 5.5 V in this
example. Therefore, the peak current will not change enough to
require an R
rectly to V

IN

resistor and the I

LIM

. Care should be taken, of course, to ensure that the

pin can be connected di-

LIM

peak current does not exceed 800 mA.

REV. 0

–7–

ADP1073

Capacitor Selection

For optimum performance, the ADP1073’s output capacitor
must be carefully selected. Choosing an inappropriate capacitor
can result in low efficiency and/or high output ripple.

Ordinary aluminum electrolytic capacitors are inexpensive, but
often have poor Equivalent Series Resistance (ESR) and
Equivalent Series Inductance (ESL). Low ESR aluminum
capacitors, specifically designed for switch mode converter
applications, are also available, and these are a better choice
than general purpose devices. Even better performance can be
achieved with tantalum capacitors, although their cost is higher.
Very low values of ESR can be achieved by using OS-CON
capacitors (Sanyo Corporation, San Diego, CA). These devices
are fairly small, available with tape-and-reel packaging and have
very low ESR.

The effects of capacitor selection on output ripple are demon­strated in Figures 12, 13 and 14. These figures show the output
of the same ADP1073 converter, which was evaluated with
three different output capacitors. In each case, the peak switch
current is 500 mA and the capacitor value is 100 µF. Figure 12
shows a Panasonic HF-series radial aluminum electrolytic. When
the switch turns off, the output voltage jumps by about 90 mV
and then decays as the inductor discharges into the capacitor.
The rise in voltage indicates an ESR of about 0.18 Ω. In
Figure 13, the aluminum electrolytic has been replaced by a
Sprague 593D-series device. In this case the output jumps
about 35 mV, which indicates an ESR of 0.07 Ω. Figure 14
shows an OS-CON SA series capacitor in the same circuit, and
ESR is only 0.02 Ω.

Figure 12. Aluminum Electrolytic

Figure 13. Tantalum Electrolytic

–8–

Figure 14. OS-CON Capacitor

If low output ripple is important, the user should consider using
the ADP3000. This device switches at 400 kHz, and the higher
switching frequency simplifies the design of the output filter.
Consult the ADP3000 data sheet for additional details.

All potential current paths must be considered when analyzing
very low power applications, and this includes capacitor leakage
current. OS-CON capacitors have leakage in the 5 µA to 10 µA
range, which will reduce efficiency when the load is also in the
microampere range. Tantalum capacitors, with typical leakage
in the 1 µA to 5 µA range, are recommended for very low power
applications.

Diode Selection

In specifying a diode, consideration must be given to speed,
forward voltage drop and reverse leakage current. When the
ADP1073 switch turns off, the diode must turn on rapidly if
high efficiency is to be maintained. Schottky rectifiers, as well as
fast signal diodes such as the 1N4148, are appropriate. The
forward voltage of the diode represents power that is not deliv­ered to the load, so V

must also be minimized. Again, Schottky

F

diodes are recommended. Leakage current is especially impor­tant in low current applications, where the leakage can be a
significant percentage of the total quiescent current.

For most circuits, the 1N5818 is a suitable companion to the
ADP1073. This diode has a V

of 0.5 V at 1 A, 4 µA to 10 µA

F

leakage and fast turn-on and turn-off times. A surface mount
version, the MBRS130T3, is also available. For applications
where the ADP1073 is “off” most of the time, such as when the
load is intermittent, a silicon diode may provide higher overall
efficiency due to lower leakage. For example, the 1N4933 has a
1 A capability, but with a leakage current of less than 1 µA. The
higher forward voltage of the 1N4933 reduces efficiency when
the ADP1073 delivers power, but the lower leakage may outweigh
the reduction in efficiency.

For switch currents of 100 mA or less, a Schottky diode such as
the BAT85 provides a V

of 0.8 V at 100 mA and leakage less

F

than 1 µA. A similar device, the BAT54, is available in an SOT-23
package. Even lower leakage, in the 1 nA to 5 nA range, can be
obtained with a 1N4148 signal diode.

General purpose rectifiers, such as the 1N4001, are not suitable
for ADP1073 circuits. These devices, which have turn-on times
of 10 µs or more, are too slow for switching power supply appli-
cations. Using such a diode “just to get started” will result in
wasted time and effort. Even if an ADP1073 circuit appears to
function with a 1N4001, the resulting performance will not be
indicative of the circuit performance when the correct diode is
used.

REV. 0

5

1

8

4

2

I

LIM

VINSW1

FB

SW2

GND

ADP1073

L1

D1
1N5818

V

OUT

C2

R3
220V

R1

R2

V

IN

3

C1

I

LIM

V

IN

SW1

FB

SW2

GND

ADP1073

L1

D1
1N5818

2V

OUT

C2

R3

R2

R1

1V

IN

C1

ADP1073

Circuit Operation, Step-Up (Boost) Mode

In boost mode, the ADP1073 produces an output voltage that is
higher than the input voltage. For example, +5 V can be
derived from one alkaline cell (+1.5 V), or +12 V can be
generated from a +5 V logic power supply.

Figure 15 shows an ADP1073 configured for step-up operation.
The collector of the internal power switch is connected to the
output side of the inductor, while the emitter is connected to
GND. When the switch turns on, Pin SW1 is pulled near ground.
This action forces a voltage across L1 equal to V

IN–VCE(SAT)

current begins to flow through L1. This current reaches a final
value (ignoring second-order effects) of:

V

I

PEAK

IN–VCE(SAT )

≅

L

×38 µs

where 38 µs is the ADP1073 switch’s “on” time.

2

SW2

4

L1 D1

3

SW1

8

FB

R1

C1

R2

V

IN

R3*

1

I

LIMVIN

ADP1073

GND

5

*OPTIONAL

Figure 15. Step-Up Mode Operation

When the switch turns off, the magnetic field collapses. The
polarity across the inductor changes, current begins to flow
through D1 into the load and the output voltage is driven above
the input voltage.

The output voltage is fed back to the ADP1073 via resistors R1
and R2. When the voltage at pin FB falls below 212 mV, SW1
turns “on” again and the cycle repeats. The output voltage is
therefore set by the formula:





V

=212 mV × 1+

OUT

R1





R2





The circuit of Figure 15 shows a direct current path from VIN to

, via the inductor and D1. Therefore, the boost converter

V

OUT

is not protected if the output is short circuited to ground.

Circuit Operation, Step-Down (Buck) Mode)

The ADP1073’s step-down mode is used to produce an output
voltage that is lower than the input voltage. For example, the
output of four NiCd cells (+4.8 V) can be converted to a +3.3 V
logic supply.

A typical configuration for step-down operation of the ADP1073
is shown in Figure 16. In this case, the collector of the internal
power switch is connected to V

and the emitter drives the

IN

inductor. When the switch turns on, SW2 is pulled up toward

. This forces a voltage across L1 equal to (VIN – VCE) – V

V

IN

and causes current to flow in L1. This current reaches a final
value of:

V

where 38 µs is the ADP1073 switch’s “on” time.

REV. 0

I

PEAK

IN–VCE–VOUT

≅

×38 µs

L

and

Figure 16. Step-Down Mode Operation

When the switch turns off, the magnetic field collapses. The
polarity across the inductor changes and the switch side of the
inductor is driven below ground. Schottky diode D1 then turns
on and current flows into the load. Notice that the Absolute
Maximum Rating for the ADP1073’s SW2 pin is 0.5 V below
ground. To avoid exceeding this limit, D1 must be a Schottky

V

OUT

diode. Using a silicon diode in this application will generate
forward voltages above 0.5 V, which will cause potentially dam­aging power dissipation within the ADP1073.

The output voltage of the buck regulator is fed back to the
ADP1073’s FB pin by resistors R1 and R2. When the voltage at
pin FB falls below 212 mV, the internal power switch turns
“on” again and the cycle repeats. The output voltage is set by
the formula:

V

OUT

=212 mV × 1+





R1





R2





The output voltage should be limited to 6.2 V or less when
using the ADP1073 in step-down mode.

If the input voltage to the ADP1073 varies over a wide range, a
current limiting resistor at Pin 1 may be required. If a particular
circuit requires high peak inductor current with minimum input
supply voltage the peak current may exceed the switch maximum
rating and/or saturate the inductor when the supply voltage is at the
maximum value. See the Limiting the Switch Current section of
this data sheet for specific recommendations.

Positive-to-Negative Conversion

The ADP1073 can convert a positive input voltage to a negative
output voltage, as shown in Figure 17. This circuit is essentially
identical to the step-down application of Figure 16, except that
the “output” side of the inductor is connected to power ground.
When the ADP1073’s internal power switch turns off, current

) to a negative

OUT

OUT

flowing in the inductor forces the output (–V

,

Figure 17. A Positive-to-Negative Converter

potential. The ADP1073 will continue to turn the switch on
until its FB pin is 212 mV above its GND pin, so the output
voltage is determined by the formula:

–9–

ADP1073





V

=212 mV × 1+

OUT

The design criteria for the step-down application also apply to
the positive-to-negative converter. The output voltage should be
limited to |6.2 V| and D1 must be a Schottky diode to prevent
excessive power dissipation in the ADP1073.

Negative-to-Positive Conversion

The circuit of Figure 18 converts a negative input voltage to a
positive output voltage. Operation of this circuit configuration is
similar to the step-up topology of Figure 16, except that the cur­rent through feedback resistor R1 is level-shifted below ground
by a PNP transistor. The voltage across R1 is (V
However, diode D2 level-shifts the base of Q1 about 0.6 V below
ground, thereby cancelling the V
also reduces the circuit’s output voltage sensitivity to tempera­ture, which would otherwise be dominated by the –2 mV/°C V
contribution of Q1. The output voltage for this circuit is deter­mined by the formula:

V

=212 mV × 1+

OUT

Unlike the positive step-up converter, the negative-to-positive
converter’s output voltage can be either higher or lower than the
input voltage.

R1





R2





– V

OUT

BE(Q1)

of Q1. The addition of D2

BE





R1





R2





).

BE

the switch turns on for the next cycle, the inductor current
begins to ramp up from the residual level. If the switch ON time
remains constant, the inductor current will increase to a high
level (see Figure 19). This increases output ripple and can
require a larger inductor and capacitor. By controlling switch
current with the I

resistor, output ripple current can be main-

LIM

tained at the design values. Figure 20 illustrates the action of the

circuit.

I

LIM

Figure 19. (I

Operation, R

LIM

LIM

= 0 Ω)

D1

1N5818

NEGATIVE

INPUT

L1

R

LIM

I

V

LIM

IN

C2

ADP1073

AO SET

NC NC

SW1

FB

SW2GND

R1

Q1

2N3906

R2

D2

1N4148

10kV

C

L

POSITIVE
OUTPUT

Figure 18. A Negative-to-Positive Converter

Limiting the Switch Current

The ADP1073’s R

pin permits the switch current to be lim-

LIM

ited with a single resistor. This current limiting action occurs on
a pulse by pulse basis. This feature allows the input voltage to
vary over a wide range without saturating the inductor or ex­ceeding the maximum switch rating. For example, a particular
design may require peak switch current of 800 mA with a 2.0 V
input. If V

rises to 4 V, however, the switch current will exceed

IN

1.6 A. The ADP1073 limits switch current to 1.5 A and thereby
protects the switch, but the output ripple will increase. Selecting
the proper resistor will limit the switch current to 800 mA, even

increases. The relationship between R

if V

IN

and maximum

LIM

switch current is shown in Figure 4.
The I

feature is also valuable for controlling inductor current

LIM

when the ADP1073 goes into continuous conduction mode. This
occurs in the step-up mode when the following condition is met:

V

OUT+VDIODE

VIN–V

SW

<

1– DC

1

where DC is the ADP1073’s duty cycle.
When this relationship exists, the inductor current does not go

all the way to zero during the time that the switch is OFF. When

Figure 20. (I

The internal structure of the I

Operation, R

LIM

circuit is shown in Figure 21.

LIM

= 240 Ω)

LIM

Q1 is the ADP1073’s internal power switch, which is paralleled
by sense transistor Q2. The relative sizes of Q1 and Q2 are
scaled so that I
internal 80 Ω resistor and through the R

is 0.5% of IQ1. Current flows to Q2 through an

Q2

resistor. These two

LIM

resistors parallel the base-emitter junction of the oscillator­disable transistor, Q3. When the voltage across R1 and R

LIM

exceeds 0.6 V, Q3 turns on and terminates the output pulse. If
only the 80 Ω internal resistor is used (i.e., the I
nected directly to V

1.5 A. Figure 4 gives R

), the maximum switch current will be

IN

values for lower current-limit values.

LIM

pin is con-

LIM

The delay through the current limiting circuit is approximately
2 µs. If the switch ON time is reduced to less than 5 µs, accu-
racy of the current trip point is reduced. Attempting to program
a switch ON time of 2 µs or less will produce spurious responses
in the switch ON time. However, the ADP1073 will still provide
a properly regulated output voltage.

–10–

REV. 0

I

V

IN

+5V

GND

ADP1073

R1

AO

SET

R2
33kV

47kV

TO
PROCESSOR

212mV

REF

V

BAT

R3

1.6MV

D1

I

LIM

V

IN

SW1

FB

SW2GND

ADP1073

L1

R1

C1

AO

R2

R3

680kV

SET

V

BAT

V

OUT

V

OUT

= ( +1) (212mV

)

R1
R2

LIM

R1
80V
(INTERNAL)

Q2

SW1

Q1

SW2

V

IN

ADP1073

Q3

OSCILLATOR

R

LIM

(EXTERNAL)

DRIVER

Figure 21. Current Limit Operation

Programming the Gain Block

The gain block of the ADP1073 can be used as a low battery
detector, error amplifier or linear post regulator. The gain block
consists of an op amp with PNP inputs and an open-collector
NPN output. The inverting input is internally connected to the
ADP1073’s 212 mV reference, while the noninverting input is
available at the SET pin. The NPN output transistor will sink
about 100 µA.

Figure 22a shows the gain block configured as a low-battery
monitor. Resistors R1 and R2 should be set to high values to
reduce quiescent current, but not so high that bias current in
the SET input causes large errors. A value of 100 kΩ for R2 is a
good compromise. The value for R1 is then calculated from the
formula:

LOBATT

212 mV

− 212 mV

R2

where V

V

R1=

is the desired low battery trip point. Since the

LOBATT

gain block output is an open-collector NPN, a pull-up resistor
should be connected to the positive logic power supply.

+5V

ADP1073

R1

V

BAT

R2

212mV

SET

GND

V

IN

REF

R1 = R2 ( –1

V

= BATTERY TRIP POINT

LB

AO

V

LB

212mV

100kV

TO
PROCESSOR

)

Figure 22a. Setting the Low Battery Detector Trip Point

ADP1073

Figure 22b. Adding Hysteresis to the Low Battery Detector

The circuit of Figure 22a may produce multiple pulses when
approaching the trip point, due to noise coupled into the SET
input. To prevent multiple interrupts to the digital logic, hyster­esis can be added to the circuit (Figure 22b). Resistor R
a value of 1 MΩ to 10 MΩ, provides the hysteresis. The addi­tion of R

will change the trip point slightly, so the new value

HYS

for R1 will be:

R1=

V



212 mV



R2



LOBATT



–





– 212 mV



V

–212 mV

L



R



L+RHYS






where VL is the logic power supply voltage, RL is the pull-up
resistor and R

creates the hysteresis.

HYS

The gain block can also be used as a control element to reduce
output ripple. The ADP3000 is normally recommended for low­ripple applications, but its minimum input voltage is 2 V. The
gain-block technique using the ADP1073 can be useful for step­up converters operating down to 1 V.

A step-up converter using this technique is shown in Figure 23.
This configuration uses the gain block to sense the output volt­age and control the comparator. The result is that the compara­tor hysteresis is reduced by the open loop gain of the gain block.
Output ripple can be reduced to only a few millivolts with this
technique, versus a typical value of 150 mV for a +5 V converter
using just the comparator. For best results, a large output
capacitor (1000 µF or more) should be specified. This tech-
nique can also be used for step-down or inverting applications,
but the ADP3000 is usually a more appropriate choice. See the
ADP3000 data sheet for further details.

HYS

, with

REV. 0

Figure 23. Using the Gain Block to Reduce Output Ripple

–11–

ADP1073

1N5818

I

LIM

V

IN

SW1

SW2GND

ADP1073-12

L1

*

120mH

47mF

SENSE

1.5 VOLT
CELL

12V OUTPUT
5mA AT V

BATTERY

= 1.0V

12mA AT V

BATTERY

= 1.5V

*

L1 = GOWANDA GA10-123k

OR CADDELL-BURNS 7300-14

1N5818

I

LIMVIN SW1

SW2GND

ADP1073-12

L1

*

68mH

47mF

51V

SENSE

TWO

1.5 VOLT
CELLS

12V OUTPUT
25mA AT V

BATTERY

= 2.0V

*

L1 = GOWANDA GA10-682k

OR CADDELL-BURNS 7300-11

V

SET

*NON-POLARIZED

–Typical Application Circuits

1MV

+12V

1mF*

IIN =

V1

V2 – V1

100V

100V

V2

100mF

ADP1073

CIRCUIT

Figure 24. Test Circuit Measures No Load Quiescent
Current of ADP1073 Converter

*

L1

1N5818

120mH

**

**

9V OUTPUT
5mA AT V
12mA AT V

47mF

BATTERY

BATTERY

1.5 VOLT
CELL

220V

I

V

LIM

ADP1073

*

L1 = GOWANDA GA10-123k
OR CADDELL-BURNS 7300-14
**

1% METAL FILM

SW1

IN

FB

SW2GND

1.00MV

23.3kV

Figure 25. 1.5 V to 9 V Step-Up Converter

*

L1

68mH

1N5818

5V OUTPUT
100mA
AT V

BATTERY

100mF

TWO

1.5 VOLT
CELLS

56V

I

V

LIM

ADP1073-5

*

L1 = GOWANDA GA10-682k

OR CADDELL-BURNS 7300-11

SW1

IN

SENSE

SW2GND

Figure 26. 3 V to 5 V Step-Up Converter

= 2.0V

= 1.00V

= 1.5V

TWO

1.5 VOLT
CELLS

Figure 28. 1.5 V to 12 V Step-Up Converter

Figure 29. 3 V to 12 V Step-Up Converter

*

L1

1N5818

68mH

51V

I

V

LIM

ADP1073

*

L1 = GOWANDA GA10-682k
OR CADDELL-BURNS 7300-11
**

1% METAL FILM

SW1

IN

FB

SW2GND

1.00MV**

14.3kV**

15V OUTPUT
20mA AT V

47mF

BATTERY

Figure 30. 3 V to 15 V Step-Up Converter

= 2.0V

L1

120mH

220V

I

V

LIM

1.5 VOLT
CELL

*

L1 = GOWANDA GA10-123k
OR CADDELL-BURNS 7300-14
**

1% METAL FILM

IN

ADP1073

SW2GND

Figure 27. 1.5 V to 3 V Step-Up Converter

*

SW1

FB

1N5818

536kV**

40.2kV**

3V OUTPUT
15mA AT V

100mF

BATTERY

= 1.00V

–12–

5 V

IN

I

100mF

LIM

ADP1073

*

L1 = GOWANDA GA10-153k
OR CADDELL-BURNS 7200-15
**

1% METAL FILM

*

L1

1N5818

150mH

V

SW1

IN

FB

SW2GND

1MV**

14.3kV**

Figure 31. 5 V to 15 V Step-Up Converter

15V OUTPUT
100mA AT 4.5 V

100mF

IN

REV. 0

ADP1073

*L1 = GOWANDA GA10-103k
OR CADDELL-BURNS 7300-13

1N5818

I

LIM

V

IN

SW1

SW2GND

ADP1073

100mF

220V

FB

9 VOLT

BATTERY

3V OUTPUT

L1

*

100mH

536kV

40.2kV

*

L1 = GOWANDA GA10-103k

OR CADDELL-BURNS 7300-13

1N5818

I

LIMVIN SW1

SW2GND

ADP1073-5

100mF

220V

SENSE

9 VOLT

BATTERY

5V OUTPUT

L1

*

100mH

*

L1 = GOWANDA GA10-472k
OR CADDELL-BURNS 7300-14
MINIMUM START-UP VOLTAGE = 1.1V

I

LIM

V

IN

SW1

SW2GND

ADP1073-5

100mF

56V

SENSE

1.5 VOLT
CELL

5V OUTPUT
25mA

L1

*

47mH

2N3906

2.2V

1N5818

5 V

IN

I

100mF

LIM

ADP1073-12

*

L1 = GOWANDA GA20-153k

OR CADDELL-BURNS 7200-15

*

L1

150mH

V

IN

SW2GND

SW1

SENSE

1N5818

12V OUTPUT
100mA AT 4.5 V

100mF

IN

Figure 32. 5 V to 12 V Step-Up Converter

*

1.5 VOLT
CELL

SHUTDOWN OPERATE

*

L1 = GOWANDA GA10-822k
OR CADDELL-BURNS 7200-12
**

1% METAL FILM

I

LIM

ADP1073

L1

82mH

V

IN

1N5818

SW1

FB

SW2GND

1N4148

909kV**

40.2kV**

74C04

5V OUTPUT

100mF

Figure 33. 1.5 V to 5 V Step-Up Converter with Logic
Shutdown

*

L1

1N5818

82mH

5V OUTPUT

Figure 35. 9 V to 3 V Step-Down Converter

Figure 36. 9 V to 5 V Step-Down Converter

442kV**

1.5 VOLT
CELL

100kV**

*

L1 = GOWANDA GA10-822k
OR CADDELL-BURNS 7300-12
**

1% METAL FILM

7

Figure 34. 1.5 V to 5 V Step-Up Converter with Low
Battery Detector

REV. 0

I

V

LIM

IN

SET

ADP1073-5

SW1

SENSE

SW2GND

AO

100kV

100mF

LO BATT
GOES LOW
AT V

BATTERY

= 1.15V

Figure 37. 1.5 V to 5 V Bootstrapped Step-Up Converter

–13–

ADP1073

1.5 VOLT
CELL

5V OUTPUT
5mA AT
V

BATTERY

= 1.00V

*

L1 = GOWANDA GA10-473k
OR CADDELL-BURNS 7300-21
**

1% METAL FILM

EFFICIENCY = 83% AT 5mA LOAD

1N5818

I

LIM

V

IN

SW1

SW2GND

ADP1073

L1

*

470mH

FB

680kV

SET

909kV**

40.2kV**

100mF
OS-CON

AO

10mV p-p RIPPLE

51V

*

L1 = COILTRONICS

CTX25-5-52

**

1% METAL FILM

I

LIM

V

IN

SW1

SW2GND

ADP1073

560kV

FB

OUTPUT
+6V, 1A
AT V

IN

= 3V

L1

*

25mH

2200mF
10V

MTP3055EL

1000mF
10V

AO

549kV**

SET

20kV**

1N5818

5.1kV

2N3906

1N5820

INPUT

3V TO 6V

(2 LITHIUM CELLS)

5V TO MEMORY

4.5V WHEN MAIN
SUPPLY OPEN

100mF***

1.5 VOLT
CELL

5V

MAIN SUPPLY

*

L1

1N5818

82mH

I

V

LIM

ADP1073

*

L1 = GOWANDA GA10-822k
OR CADDELL-BURNS 7300-12
**1% METAL FILM

***OPTIONAL

SW1

IN

FB

SW2GND

806kV**

40.2kV**

Figure 38. Memory Backup Supply

*

L1

1N5818

68mH

1MV**

40.3kV**

5V OUTPUT
100mA
LOCKOUT
AT 1.6V

100mF

3 VOLT

CELL

100kV

909kV**

I

100kV

2N3906

2.2MV

100kV

*

L1 = GOWANDA GA10-682k
OR CADDELL-BURNS 7300-11
**

1% METAL FILM

LIM

AO

ADP1073

SET

51V

V

IN

SW1

FB

SW2GND

Figure 39. 3 V to 5 V Step-Up Converter with Undervoltage
Lockout

Figure 41. 1.5 V to 5 V Very Low Noise Step-Up Converter

6.5V

TO 12V

680kV

*

L1 = GOWANDA GA10-472k
OR CADDELL-BURNS 7300-09
**

1% METAL FILM

EFFICIENCY = 80%

= 130µA

I

Q

OUTPUT RIPPLE = 100mV p-p

I

LIM

FB

ADP1073

AO

V

SW1

IN

SET

SW2GND

L1

47mH

1N5818

*

5V

OUT

90mA
AT 6.5V

100mF
OS-CON

900kV**

40.2kV**

IN

Figure 42. 9 V to 5 V Reduced Noise Step-Down Converter

1.5 VOLT

*

L1

1N5818

82mH

5V OUTPUT
20mV p-p RIPPLE

100mF
OS-CON

CELL

680kV

I

V

LIM

FB

ADP1073

AO

*

L1 = GOWANDA GA10-822k
OR CADDELL-BURNS 7300-12
**

1% METAL FILM

SW1

IN

SET

SW2GND

909kV**

40.2kV**

Figure 40. 1.5 V to 5 V Low Noise Step-Up Converter

–14–

Figure 43. 3 V to 6 V @ 1 A Step-Up Converter

REV. 0

0.210 (5.33)
MAX

0.160 (4.06)

0.115 (2.93)

0.022 (0.558)

0.014 (0.356)

0.1574 (4.00)

0.1497 (3.80)

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Lead Plastic DIP

(N-8)

0.430 (10.92)

0.348 (8.84)

8

14

PIN 1

0.100
(2.54)

BSC

5

0.280 (7.11)

0.240 (6.10)

0.060 (1.52)

0.015 (0.38)

0.070 (1.77)

0.045 (1.15)

0.130
(3.30)
MIN

SEATING
PLANE

0.325 (8.25)

0.300 (7.62)

0.015 (0.381)

0.008 (0.204)

8-Lead Small Outline Package

(SO-8)

0.1968 (5.00)

0.1890 (4.80)

8

5

0.2440 (6.20)

41

0.2284 (5.80)

ADP1073

0.195 (4.95)

0.115 (2.93)

0.0098 (0.25)

0.0040 (0.10)

SEATING

PLANE

PIN 1

0.0500
(1.27)

BSC

0.0688 (1.75)

0.0532 (1.35)

0.0192 (0.49)

0.0138 (0.35)

0.0098 (0.25)

0.0075 (0.19)

0.0196 (0.50)

0.0099 (0.25)

8°
0°

0.0500 (1.27)

0.0160 (0.41)

x 45°

REV. 0

–15–

C2965–8–10/97

–16–

PRINTED IN U.S.A.