REV. 0
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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.
a
ADP3000
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 World Wide Web Site: http://www.analog.com
Fax: 617/326-8703 © Analog Devices, Inc., 1997
Micropower Step-Up/Step-Down
Fixed 3.3 V, 5 V, 12 V and Adjustable
High Frequency Switching Regulator
FUNCTIONAL BLOCK DIAGRAM
COMPARATOR
GAIN BLOCK/
ERROR AMP
400kHz
OSCILLATOR
DRIVER
A1
1.245V
REFERENCE
R1 R2
ADP3000
SET
V
IN
GND SENSE
A0
I
LIM
SW1
SW2
FEATURES
Operates at Supply Voltages from 2 V to 30 V
Works in Step-Up or Step-Down Mode
Very Few External Components Required
High Frequency Operation Up to 400 kHz
Low Battery Detector on Chip
User Adjustable Current Limit
Fixed and Adjustable Output Voltage
8-Pin DIP and SO-8 Package
Small Inductors and Capacitors
APPLICATIONS
Notebook, Palmtop Computers
Cellular Telephones
Hard Disk Drives
Portable Instruments
Pagers
GENERAL DESCRIPTION
The ADP3000 is a versatile step-up/step-down switching
regulator that operates from an input supply voltage of 2 V to
12 V in step-up mode and up to 30 V in step-down mode.
The ADP3000 operates in Pulse Frequency Mode (PFM) and
consumes only 500 µA, making it highly suitable for applica-
tions that require low quiescent current.
The ADP3000 can deliver an output current of 100 mA at
3 V from a 5 V input in step-down configuration and 180 mA at
3.3 V from a 2 V input in step-up configuration.
The auxiliary gain amplifier can be used as a low battery detector,
linear regulator undervoltage lockout or error amplifier.
The ADP3000 operates at 400 kHz switching frequency. This
allows the use of small external components (inductors and
capacitors), making the device very suitable for space constrained
designs.
ADP3000-3.3V
1 2
3
8
4
5
I
LIM
V
IN
SW1
FB
(SENSE)
SW2GND
+
100µF
10V 120Ω
6.8µH IN5817
C1
100µF
10V
V
IN
2V–3.2V 3.3V @
180mA
C1, C2: AVX TPS D107 M010R0100
L1: SUMIDA CD43-6R8
Figure 1. Typical Application
ADP3000
1 2 3
8
4
5
I
LIM
V
IN
SW1
FB
SW2
GND
C1
100µF
10V
R
LIM
120Ω
L1
10µH
V
IN
5V–6V
C1, C2: AVX TPS D107 M010R0100
L1: SUMIDA CD43-100
+
D1
1N5818
CL
100µF
10V
R2
150kΩ
1%
R1
110kΩ
1%
V
OUT
3V
100mA
Figure 2. Step-Down Mode Operation
–2– REV. 0
ADP3000–SPECIFICATIONS
ADP3000
Parameter Conditions Symbol Min Typ Max Units
INPUT VOLTAGE Step-Up Mode V
IN
2.0 12.6 V
Step-Down Mode 30.0 V
SHUTDOWN QUIESCENT CURRENT V
FB
> 1.43 V; V
SENSE
> 1.1 × V
OUT
I
Q
500 µA
COMPARATOR TRIP POINT ADP3000
1
1.20 1.245 1.30 V
VOLTAGE
OUTPUT SENSE VOLTAGE ADP3000-3.3
2
3.135 3.3 3.465 V
ADP3000-5
2
V
OUT
4.75 5.00 5.25 V
ADP3000-12
2
11.40 12.00 12.60 V
COMPARATOR HYSTERESIS ADP3000 8 12.5 mV
OUTPUT HYSTERESIS ADP3000-3.3 32 50 mV
ADP3000-5 32 50 mV
ADP3000-12 75 120 mV
OSCILLATOR FREQUENCY f
OSC
350 400 450 kHz
DUTY CYCLE V
FB
> V
REF
D6580 %
SWITCH ON TIME I
LIM
Tied to V
IN
, V
FB
= 0 t
ON
1.5 2 2.55 µs
SWITCH SATURATION VOLTAGE T
A
= +25°C
STEP-UP MODE V
IN
= 3.0 V, I
SW
= 650 mA V
SAT
0.5 0.75 V
V
IN
= 5.0 V, I
SW
= 1 A 0.8 1.1 V
STEP-DOWN MODE V
IN
= 12 V, I
SW
= 650 mA 1.1 1.5 V
FEEDBACK PIN BIAS CURRENT ADP3000 V
FB
= 0 V I
FB
160 330 nA
SET PIN BIAS CURRENT V
SET
= V
REF
I
SET
200 400 nA
GAIN BLOCK OUTPUT LOW I
SINK
= 300 µAV
OL
0.15 0.4 V
V
SET
= 1.00 V
REFERENCE LINE REGULATION 5 V ≤ V
IN
≤ 30 V 0.02 0.15 %/V
2 V ≤ V
IN
≤ 5 V 0.2 0.6 %/V
GAIN BLOCK GAIN R
L
= 100 kΩ
3
A
V
1000 6000 V/V
GAIN BLOCK CURRENT SINK V
SET
≤ 1 V I
SINK
300 µA
CURRENT LIMIT 220 Ω from I
LIM
to V
IN
I
LIM
400 mA
CURRENT LIMIT TEMPERATURE
COEFFICIENT –0.3 %/°C
SWITCH OFF LEAKAGE CURRENT Measured at SW1 Pin 1 10 µA
V
SW1
= 12 V, T
A
= +25°C
MAXIMUM EXCURSION BELOW GND T
A
= +25°C
I
SW1
≤ 10 µA, Switch Off –400 –350 mV
NOTES
1
This specification guarantees that both the high and low trip point of the comparator fall within the 1.20 V to 1.30 V range.
2
The output voltage waveform will exhibit a sawtooth shape due to the comparator hysteresis. The output voltage on the fixed output versions will always be within the
specified range.
3
100 kΩ resistor connected between a 5 V source and the AO pin.
*All limits at temperature extremes are guaranteed via correlation using standard statistical methods.
Specifications subject to change without notice.
(08C ≤ TA ≤ +708C, VIN = 3 V unless otherwise noted)*
ADP3000
–3–
REV. 0
PIN DESCRIPTIONS
Mnemonic Function
I
LIM
For normal conditions this pin is connected to
V
IN
. When lower current is required, a resistor
should be connected between I
LIM
and V
IN.
Limiting the switch current to 400 mA is
achieved by connecting a 220 Ω resistor.
V
IN
Input Voltage.
SW1 Collector of power transistor. For step-down
configuration, connect to V
IN.
For step-up
configuration, connect to an inductor/diode.
SW2 Emitter of power transistor. For step-down
configuration, connect to inductor/diode.
For step-up configuration, connect to ground.
Do not allow this pin to go more than a diode
drop below ground.
GND Ground.
AO Auxiliary Gain (GB) output. The open col-
lector can sink 300 µA. It can be left open
if not used.
SET SET Gain amplifier input. The amplifier’s
positive input is connected to SET pin and its
negative input is connected to 1.245 V. It can
be left open if not used.
FB/SENSE On the ADP3000 (adjustable) version, this pin
is connected to the comparator input. On the
ADP3000-3.3, ADP3000-5 and ADP3000-12,
the pin goes directly to the internal resistor
divider that sets the output voltage.
WARNING!
ESD SENSITIVE DEVICE
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 ADP3000 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.
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 . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to V
IN
Feedback Pin Voltage (ADP3000) . . . . . . . . . . . . . . . . . .5.5 V
Switch Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 A
Maximum Power Dissipation . . . . . . . . . . . . . . . . . . 500 mW
Operating Temperature Range . . . . . . . . . . . . . 0°C to +70°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . .+300°C
Thermal Impedance
SO-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170°C/W
N-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120°C/W
PIN CONFIGURATIONS
8-Lead Plastic DIP 8-Lead SOIC
(N-8) (SO-8)
1
2
3
4
8
7
6
5
TOP VIEW
(Not to Scale)
ADP3000
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)
ADP3000
I
LIM
V
IN
SW1
SW2
FB (SENSE)*
SET
AO
GND
* FIXED VERSIONS
ORDERING GUIDE
Output Package
Model Voltage Option
ADP3000AN-3.3 3.3 V N-8
ADP3000AR-3.3 3.3 V SO-8
ADP3000AN-5 5 V N-8
ADP3000AR-5 5 V SO-8
ADP3000AN-12 12 V N-8
ADP3000AR-12 12 V SO-8
ADP3000AN Adjustable N-8
ADP3000AR Adjustable SO-8
N = plastic DIP, SO = small outline package.
Figure 3a. Functional Block Diagram for Adjustable Version Figure 3b. Functional Block Diagram for Fixed Version
COMPARATOR
GAIN BLOCK/
ERROR AMP
OSCILLATOR
DRIVER
A2
1.245V
REFERENCE
ADP3000
SET
V
IN
GND FB
A0
I
LIM
SW1
SW2
A1
COMPARATOR
GAIN BLOCK/
ERROR AMP
OSCILLATOR
DRIVER
A1
1.245V
REFERENCE
R1 R2
ADP3000
SET
V
IN
GND SENSE
A0
I
LIM
SW1
SW2
ADP3000
–4– REV. 0
–Typical Characteristics
SWITCH CURRENT – A
ON VOLTAGE – V
2.5
2.0
0
0.1 0.2 1.5
0.4 0.6 0.8 1.0 1.2 1.4
1.5
1.0
0.5
V
IN
= 2V @ T
A
= +25
°
C
V
IN
= 3V @ T
A
= +25
°
C
V
IN
= 5V @ T
A
= +25
°
C
Figure 4. Switch ON Voltage vs.
Switch Current in Step-Up Mode
INPUT VOLTAGE – V
406
401
396 24 306 8 10 12 15 18 21 24 27
405
402
400
399
404
403
OSCILLATOR FREQUENCY – kHz
OSCILLATOR FREQUENCY –
@ TA = +25°C
Figure 7. Oscillator Frequency vs.
Input Voltage
RLIM – Ω
SWITCH CURRENT – A
1.8
1.6
0110 1k
100
0.6
0.2
0.4
1.0
0.8
1.4
1.2
TA = +85°C
TA = 0°C
TA = +25°C
VIN = 3V
Figure 8c. Maximum Switch Current
vs. R
LIM
in Step-Up Mode (3 V)
SWITCH CURRENT – A
0.1
V
CE(SAT)
– V
0.2 0.9
0.3 0.4 0.5 0.6 0.8
0.0
0.8
0.6
0.4
0.2
1.0
V
IN
= 12V @ T
A
= +25
°
C
V
IN
= 5V @ T
A
= +25
°
C
1.4
1.2
Figure 5. Saturation Voltage vs.
Switch Current in Step-Down Mode
RLIM – Ω
SWITCH CURRENT – A
0.8
0.7
0110 1k
100
0.2
0.1
0.4
0.3
0.6
0.5
TA = +25°C
TA = +85°C
TA = 0°C
VIN = 5V
Figure 8a. Maximum Switch Current
vs. R
LIM
in Step-Down Mode (5 V)
TEMPERATURE –
°
C (T
A
)
OSCILLATOR FREQUENCY – kHz
440
430
330–40 0 85
25 70
380
360
350
340
420
410
400
390
370
Figure 9. Oscillator Frequency vs.
Temperature
INPUT VOLTAGE – V
1400
0
1.5 3 30
6 9 12 15 18 21 24 27
1200
1000
800
600
400
200
QUIESCENT CURRENT – µA
QUIESCENT CURRENT @ T
A
= +25
°
C
Figure 6. Quiescent Current vs.
Input Voltage
RLIM – Ω
SWITCH CURRENT – A
1.8
1.6
0110 1k
100
0.6
0.2
0.4
1.0
0.8
1.4
1.2
TA = +25°C
TA = +85°C
TA = 0°C
VIN = 12V
Figure 8b. Maximum Switch Current
vs. R
LIM
in Step-Down Mode (12 V)
TEMPERATURE –
°
C (T
A
)
ON TIME – µs
2.30
2.25
1.80–40 0 85
25 70
2.00
1.95
1.90
1.85
2.20
2.15
2.10
2.05
Figure 10. Switch ON Time vs.
Temperature
ADP3000
–5–
REV. 0
TEMPERATURE –
°
C (T
A
)
DUTY CYCLE – %
100
90
0–40 0 85
25 70
40
30
20
10
80
70
60
50
Figure 11. Duty Cycle vs.
Temperature
TEMPERATURE –
°
C (T
A
)
BIAS CURRENT – µA
250
200
0–40 0 85
25 70
150
100
50
Figure 14. Feedback Bias Current
vs. Temperature
TEMPERATURE –
°
C (T
A
)
SATURATION VOLTAGE – V
0.56
0.54
0.42
–40 0 85
25 70
0.50
0.48
0.46
0.44
0.52
V
IN
= 3V @ I
SW
= 0.65A
Figure 12. Saturation Voltage vs.
Temperature in Step-Up Mode
TEMPERATURE –
°
C (T
A
)
QUIESCENT CURRENT – µA
700
600
0
–40 0 8525 70
400
300
200
100
500
V
IN
= 20V
Figure 15. Quiescent Current vs.
Temperature
TEMPERATURE –
°
C (T
A
)
ON VOLTAGE – V
1.25
1.20
0.90
–40 0 8525 70
1.10
1.05
1.00
0.95
1.15 V
IN
= 12V @ I
SW
= 0.65A
Figure 13. Switch ON Voltage vs.
Temperature in Step-Down Mode
TEMPERATURE – °C (TA)
BIAS CURRENT – µA
350
300
0
–40 0 8525 70
200
150
100
50
250
Figure 16. Set Pin Bias Current vs.
Temperature
ADP3000
–6– REV. 0
THEORY OF OPERATION
The ADP3000 is a versatile, high frequency, 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 high perfor-
mance with low quiescent current.
A functional block diagram of the ADP3000 is shown in
Figure 3a. The internal 1.245 V reference is connected to one
input of the comparator, while the other input is externally
connected (via the FB pin) to a resistor divider connected to
the regulated output. When the voltage at the FB pin falls below
1.245 V, the 400 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 1.245 V, the oscillator is shut off. While the
oscillator is off, the ADP3000 quiescent current is only 500 µA.
The comparator’s hysteresis 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
LIM
pin. When
the maximum current is exceeded, the switch is turned OFF.
The current limit circuitry has a time delay of about 0.3 µs. If
an external resistor is not used, connect I
LIM
to V
IN
. This
yields the maximum feasible current limit. Further information
on I
LIM
is included in the “Applications” section of this data
sheet. The ADP3000 internal oscillator provides typically 1.7
µs ON and 0.8 µs OFF times.
An uncommitted gain block on the ADP3000 can be con-
nected as a low battery detector. The inverting input of the
gain block is internally connected to the 1.245 V reference.
The noninverting input is available at the SET pin. A resistor
divider, connected between V
IN
and GND with the junction
connected to the SET pin, causes the AO output to go LOW
when the low battery set point is exceeded. The AO output is
an open collector NPN transistor that can sink in excess of
300 µA.
The ADP3000 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 step-
up 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 ADP3000 is set with two external
resistors. Three fixed voltage models are also available:
ADP3000–3.3 (+3.3 V), ADP3000–5 (+5 V) and ADP3000–12
(+12 V). The fixed voltage models include laser-trimmed
voltage-setting resistors on the chip. On the fixed voltage models
of the ADP3000, simply connect the feedback pin (Pin 8)
directly to the output voltage.
APPLICATIONS INFORMATION
COMPONENT SELECTION
Inductor Selection
For most applications the inductor used with the ADP3000 will
fall in the range between 4.7 µH to 33 µH. Table I shows
recommended inductors and their vendors.
When selecting an inductor, it is very important to make sure
that the inductor used with the ADP3000 is able to handle a
current that is higher than the ADP3000’s current limit without
saturation.
As a rule of thumb, powdered iron cores saturate softly, whereas
Ferrite cores saturate abruptly. Rod or “open” drum core
geometry inductors saturate gradually. Inductors that saturate
gradually are easier to use. Even though rod or drum core
inductors are attractive in both price and physical size, these
types of inductors must be handled with care because they have
high magnetic radiation. Toroid or “closed” core geometry
should be used when minimizing EMI is critical.
In addition, inductor dc resistance causes power loss. It is best
to use low dc resistance inductors so that power loss in the
inductor is kept to the minimum. Typically, it is best to use an
inductor with a dc resistance lower than 0.2 Ω.
Table I. Recommended Inductors
V
endor Series Core Type Phone Numbers
Coiltronics OCTAPAC Toroid (407) 241-7876
Coiltronics UNIPAC Open (407) 241-7876
Sumida CD43, CD54 Open (847) 956-0666
Sumida CDRH62, CDRH73, Semi-Closed (847) 956-0666
CDRH64 Geometry
Capacitor Selection
For most applications, the capacitor used with the ADP3000
will fall in the range between 33 µF to 220 µF. Table II shows
recommended capacitors and their vendors.
For input and output capacitors, use low ESR type capacitors
for best efficiency and lowest ripple. Recommended capacitors
include AVX TPS series, Sprague 595D series, Panasonic HFQ
series and Sanyo OS-CON series.
When selecting a capacitor, it is important to make sure the
maximum capacitor ripple current rms rating is higher than the
ADP3000’s rms switching current.
It is best to protect the input capacitor from high turn-on cur-
rent charging surges by derating the capacitor voltage by 2:1.
For very low input or output voltage ripple requirements,
Sanyo OS-CON series capacitors can be used since this type of
capacitor has very low ESR. Alternatively, two or more tanta-
lum capacitors can be used in parallel.
ADP3000
–7–
REV. 0
Table II. Recommended Capacitors
Vendor Series Type Phone Numbers
AVX TPS Surface Mount (803) 448-9411
Sanyo OS-CON Through-Hole (619) 661-6835
Sprague 595D Surface Mount (603) 224-1961
Panasonic HFQ Through-Hole (201) 348-5200
DIODE SELECTION
The ADP3000’s high switching speed demands the use of
Schottky diodes. Suitable choices include the 1N5817, 1N5818,
1N5819, MBRS120LT3 and MBR0520LT1. Do not use fast
recovery diodes because their high forward drop lowers effi-
ciency. Neither general-purpose diodes nor small signal diodes
should be used.
PROGRAMMING THE SWITCHING CURRENT LIMIT
OF THE POWER SWITCH
The ADP3000’s R
LIM
pin permits the cycle by cycle switch
current limit to be programmed with a single external resistor.
This feature offers major advantages which ultimately decrease
the component cost and P.C.B. real estate. First, it allows the
ADP3000 to use low value, low saturation current and physi-
cally small inductors. Additionally, it allows the ADP3000 to
use a physically small surface mount tantalum capacitor with a
typical ESR of 0.1 Ω to achieve an output ripple as low as 40
mV to 80 mV, as well as low input ripple.
As a rule of thumb, the current limit is usually set to approximately
3 to 5 times the full load current for boost applications and
about 1.5–3 times of the full load current in buck applications.
The internal structure of the I
LIM
circuit is shown in Figure 17.
Q1 is the ADP3000’s internal power switch, which is paralleled
by sense transistor Q2. The relative sizes of Q1 and Q2 are
scaled so that IQ2 is 0.5% of IQ1. Current flows to Q2 through
both an internal 80 Ω resistor and the R
LIM
resistor. The voltage
on these two resistors biases the base-emitter junction of the
oscillator-disable 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
LIM
pin
is connected directly to V
IN
), the maximum switch current will
be 1.5 A. Figure 8a gives values for lower current-limit values.
V
IN
POWER
SWITCH
SW2
SW1
R
LIM
DRIVER
80Ω
(INTERNAL)
I
LIM
I
Q1
V
IN
200
(EXTERNAL)
Q2
ADP3000
Q1
400kHz
OSC
Q3
R1
Figure 17. ADP3000 Current Limit Operation
The delay through the current limiting circuit is approximately
0.3 µs. If the switch ON time is reduced to less than 1.7 µs,
accuracy of the current trip-point is reduced. Attempting to
program a switch ON time of 0.3 µs or less will produce
spurious responses in the switch ON time. However, the
ADP3000 will still provide a properly regulated output voltage.
PROGRAMMING THE GAIN BLOCK
The gain block of the ADP3000 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
ADP3000’s 1.245 V reference, while the noninverting input is
available at the SET pin. The NPN output transistor will sink in
excess of 300 µA.
Figure 18 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 33 kΩ for R2 is a
good compromise. The value for R1 is then calculated from the
formula:
R1=V
LOBATT
–1.245 V
1.245 V
R2
where V
LOBATT
is the desired low battery trip point. Since the
gain block output is an open-collector NPN, a pull-up resistor
should be connected to the positive logic power supply.
ADP3000
1.245V
REF
GND
AO
5V
R
L
47kΩ
TO
PROCESSOR
R1
V
BATT
V
IN
SET
R
HYS
R2
33kΩ1.6MΩ
V
LB
= BATTERY TRIP POINT
R1 = V
LB
– 1.245V
37.7µA
Figure 18. Setting the Low Battery Detector Trip Point
ADP3000
–8– REV. 0
The circuit of Figure 18 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 18). Resistor R
HYS
,
with a value of 1 MΩ to 10 MΩ, provides the hysteresis. The
addition of R
HYS
will change the trip point slightly, so the new
value for R1 will be:
R1=V
LOBATT
–1.245V
1.245V
R2
−V
L
−1.245V
R
L
+R
HYS
where V
L
is the logic power supply voltage, R
L
is the pull-up
resistor, and R
HYS
creates the hysteresis.
POWER TRANSISTOR PROTECTION DIODE IN STEP-
DOWN CONFIGURATION
When operating the ADP3000 in the step-down mode, the
output voltage is impressed across the internal power switch’s
emitter-base junction when the switch is off. In order to protect
the switch, a Schottky diode must be placed in a series with
SW2 when the output voltage is set to higher than 6 V. Figure
19 shows the proper way to place the protection diode, D2.
The selection of this diode is identical to the step-down commut-
ing diode (see Diode Selection section for information).
ILIM VIN SW1
FB
SW2
GND
ADP3000
C2 R3
VIN
4
1 2 3
8
5
+
L1
R1
R2
D2
VOUT > 6V
+
D1
D1, D2 = 1N5818 SCHOTTKY DIODES
C1
Figure 19. Step-Down Model V
OUT
> 6.0 V
THERMAL CONSIDERATIONS
Power dissipation internal to the ADP3000 can be approximated
with the following equations.
Step-Up
P
D
=I
SW 2
R+V
IN
I
SW
β
D1–V
IN
V
O
4I
O
I
SW
+I
Q
[]
V
IN
[]
where: I
SW
is I
LIMIT
in the case of current limit programmed
externally, or maximum inductor current in the case of
current limit not programmed externally.
R = 1 Ω (Typical R
CE(SAT)
).
D = 0.75 (Typical Duty Ratio for a Single Switching
Cycle).
V
O
= Output Voltage.
I
O
= Output Current.
V
IN
= Input Voltage.
I
Q
= 500 µA (Typical Shutdown Quiescent Current).
β = 30 (Typical Forced Beta)
Step-Down
P
D
=I
SW
V
CESAT
1+1
β
V
O
V
IN
–V
CE SAT
()
2I
O
I
SW
+I
Q
[]
V
IN
[]
where: I
SW
is I
LIMIT
in the case of current limit is programmed
externally or maximum inductor current in the case of
current limit is not programmed eternally.
V
CE(SAT)
= Check this value by applying I
SW
to Figure 8b.
1.2 V is typical value.
D = 0.75 (Typical Duty Ratio for a Single Switching
Cycle).
V
O
= Output Voltage.
I
O
= Output Current.
V
IN
= Input Voltage.
I
Q
= 500 µA (Typical Shutdown Quiescent Current).
β = 30 (Typical Forced Beta).
The temperature rise can be calculated from:
∆T=PD×θJA
where:
∆T = Temperature Rise.
P
D
= Device Power Dissipation.
θ
JA
= Thermal Resistance (Junction-to-Ambient).
As example, consider a boost converter with the following
specifications:
V
IN
= 2 V, I
O
= 180 mA, V
O
= 3.3 V.
I
SW
= 0.8 A (Externally Programmed).
With Step-Up Power Dissipation Equation:
= 185 mW
Using the SO-8 Package: ∆T = 185 mW (170°C/W) = 31.5°C.
Using the N-8 Package: ∆T = 185 mW (120°C/W) = 22.2°C.
At a 70°C ambient, die temperature would be 101.45°C for
SO-8 package and 92.2°C for N-8 package. These junction
temperatures are well below the maximum recommended
junction temperature of 125°C.
Finally, the die temperature can be decreased up to 20% by
using a large metal ground plate as ground pickup for the
ADP3000.
ADP3000
–9–
REV. 0
Typical Application Circuits
ILIM VIN SW1
SW2
SENSE
GND
ADP3000-3.3V
L1
6.8µH
120Ω
8
12
45
3
1N5817
C1
100µF
10V
+
C2
100µF
10V
+
VIN
2V → 3.2V VOUT
3.3V
180mA
L1 = SUMIDA CD43-6R8
C1, C2 = AVX TPS D107 M010R100
TYPICAL EFFICIENCY = 75%
Figure 20. 2 V to 3.3 V/180 mA Step-Up Converter
I
LIM
V
IN
SW1
SW2
SENSE
GND
ADP3000-5V
L1
6.8µH
120Ω
8
12
45
3
1N5817
C1
100µF
10V
+
C2
100µF
10V
+
V
IN
2V → 3.2V V
OUT
5V
100mA
L1 = SUMIDA CD43-6R8
C1, C2 = AVX TPS D107 M010R0100
TYPICAL EFFICIENCY = 80%
Figure 21. 2 V to 5 V/100 mA Step-Up Converter
I
LIM
V
IN
SW1
SW2
SENSE
GND
ADP3000-5V
L1
6.8µH
120Ω
8
12
45
3
1N5817
C1
100µF
10V
+
C2
100µF
10V
+
V
IN
2.7V → 4.5V V
OUT
5V
150mA
L1 = SUMIDA CD43-6R8
C1, C2 = AVX TPS D107 M010R100
TYPICAL EFFICIENCY = 80%
Figure 22. 2.7 V to 5 V/150 mA Step-Up Converter
ILIM VIN SW1
SW2
SENSE
GND
ADP3000-12V
L1
15µH
124Ω
8
12
45
3
1N5817
C1
100µF
10V
+
C2
100µF
16V
+
VIN
4.5V → 5.5V VOUT
12V
50mA
L1 = SUMIDA CD54-150
C1 = AVX TPS D107 M010R0100
C2 = AVX TPS E107 M016R0100
TYPICAL EFFICIENCY = 75%
Figure 23. 4.5 V to 12 V/ 50 mA Step-Up Converter
I
LIM
V
IN
SW1
FB
SW2
GND
ADP3000-ADJ
C1
100µF
10V
V
IN
5V → 6V
4
1 2 3
8
5
+
L1
10µH V
OUT
3V
100mA
+
D1
IN5817
R2
150kΩ
R1
110kΩ
C2
100µF
10V
120Ω
L1 = SUMIDA CD43-100
C1, C2 = AVX TPS D107 M010R100
TYPICAL EFFICIENCY = 75%
Figure 24. 5 V to 3 V/100 mA Step-Down Converter
I
LIM
V
IN
SW1
SENSE
SW2
GND
ADP3000-5V
C1
33µF
20V
V
IN
10V → 13V
4
1 2 3
8
5
+
L1
10µH V
OUT
5V
250mA
+
D1
IN5817
250Ω
L1 = SUMIDA CD43-100
C1 = AVX TPS D336 M020R0200
C2 = AVX TPS D107 M010R0100
TYPICAL EFFICIENCY = 77%
C2
100µF
10V
Figure 25. 10 V to 5 V/250 mA Step-Down Converter
ADP3000
–10– REV. 0
I
LIM
V
IN
SW1
SENSE
SW2
GND
ADP3000-5V
C1
47µF
16V
V
IN
5V
4
1 2 3
8
5
+
L1
15µH
+
240Ω
L1 = SUMIDA CD53-150
C1 = AVX TPS D476 M016R0150
C2 = AVX TPS D107 M010R0100
TYPICAL EFFICIENCY = 60%
V
OUT
–5V
100mA
C2
100µF
10V
D1
IN5817
Figure 26. 5 V to –5 V/100 mA Inverter
I
LIM
V
IN
SET
A
O
GND SW2
FB
SW1
ADP3000
IN1
IN2
GND V
O2
V
O1
ADP3302AR1
SD
1MΩ
90kΩ
100kΩ
+100µF
10V
AVX-TPS
–
120Ω
33nF
100kΩ
330kΩ
90kΩ
2N2907
(SUMIDA – CDRH62)
6.8µH
IN5817
348kΩ
1%
200kΩ
1%
+
–
100µF
10V
AVX-TPS
1µF
6V
(MLC)
1µF
6V
(MLC)
3V
100mA
3V
100mA
2.5V → 4.2V
10kΩ
Figure 27. 1 Cell LI-ION to 3 V/200 mA Converter with Shutdown at V
IN
≤
2.5 V
80
75
70
65
% EFFICIENCY
2.6 3.0 3.4 3.8 4.2
AT V
IN
≤ 2.5V
SHDN IQ = 500µA
I
O
= 100mA + 100mA
I
O
= 50mA + 50mA
V
IN
(V)
Figure 28. Typical Efficiency of the Circuit of Figure 27
ADP3000
–11–
REV. 0
8-Lead Plastic DIP 8-Lead SOIC
(N-8) (SO-8)
8
14
5
0.430 (10.92)
0.348 (8.84)
0.280 (7.11)
0.240 (6.10)
PIN 1
SEATING
PLANE
0.022 (0.558)
0.014 (0.356)
0.060 (1.52)
0.015 (0.38)
0.210 (5.33)
MAX 0.130
(3.30)
MIN
0.070 (1.77)
0.045 (1.15)
0.100
(2.54)
BSC
0.160 (4.06)
0.115 (2.93)
0.325 (8.25)
0.300 (7.62)
0.015 (0.381)
0.008 (0.204)
0.195 (4.95)
0.115 (2.93)
0.1968 (5.00)
0.1890 (4.80)
85
41
0.2440 (6.20)
0.2284 (5.80)
PIN 1
0.1574 (4.00)
0.1497 (3.80)
0.0688 (1.75)
0.0532 (1.35)
SEATING
PLANE
0.0098 (0.25)
0.0040 (0.10)
0.0192 (0.49)
0.0138 (0.35)
0.0500
(1.27)
BSC 0.0098 (0.25)
0.0075 (0.19) 0.0500 (1.27)
0.0160 (0.41)
8°
0°
0.0196 (0.50)
0.0099 (0.25) x 45°
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
–12–
C2223–12–1/97
PRINTED IN U.S.A.