AD ADP1109AAN-12 Micropower low cost fixed 3.3 v, 5 v, 12 v and adjustable dc-to-dc converter Datasheet

a
Micropower Low Cost
Fixed 3.3 V, 5 V, 12 V and Adjustable
DC-to-DC Converter
ADP1109A
FEATURES
Operates at Supply Voltages 2 V to 9 V
Fixed 3.3 V, 5 V, 12 V and Adjustable Output
Minimum External Components Required
Ground Current: 460 mA
Oscillator Frequency: 120 kHz
Logic Shutdown
8-Lead DIP and SO-8 Packages
APPLICATIONS
Cellular Telephones
Single-Cell to 5 V Converters
Laptop and Palmtop Computers
Pagers
Cameras
Battery Backup Supplies
Portable Instruments
Laser Diode Drivers
Hand-Held Inventory Computers
FUNCTIONAL BLOCK DIAGRAM
VIN
SENSE
ADP1109A-3.3: R1 = 152kV
ADP1109A-5: R1 = 83kV
ADP1109A-12: R1 = 29kV
R2
250kV
SW
COMPARATOR
1.25V
REFERENCE
120kHz
OSCILLATOR
A1
Q1
DRIVER
R1
SHUTDOWN
GND
VIN
PGND
FB
ADP1109A
SW
COMPARATOR
GENERAL DESCRIPTION
1.25V
REFERENCE
120kHz
OSCILLATOR
A1
The ADP1109A is a versatile step-up switching regulator. The
device requires only minimal external components to operate as
a complete switching regulator.
The ADP1109A-5 can deliver 100 mA at 5 V from a 3 V input
and the ADP1109A-12 can deliver 60 mA at 12 V from a 5 V
input. The device also features a logic controlled shutdown
capability that, when a logic low is applied, will shut down the
oscillator. The 120 kHz operating frequency allows for the use
of small surface mount components.
Q1
DRIVER
SHUTDOWN
GND
PGND
TYPICAL APPLICATION
The gated oscillator capability eliminates the need for frequency
compensation.
L1
33mH
D1
3
VIN
5V
1
SW
VIN
VOUT
12V
60mA
SENSE 8
ADP1109A-12
7
SHUTDOWN
PGND
GND
4
SHUTDOWN/PROGRAM
5
+
C1
22mF
16V
Flash Memory VPP Generator
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1997
ADP1109A–SPECIFICATIONS (08C ≤ T ≤ 708C, V
A
IN
= 3 V unless otherwise noted)
Parameter
Conditions
VS
QUIESCENT CURRENT
Switch Off
IQ
INPUT VOLTAGE
VIN
COMPARATOR TRIP POINT
VOLTAGE
ADP1109A
OUTPUT VOLTAGE
ADP1109A-3.3
ADP1109A-5
ADP1109A-12
2 V ≤ VIN ≤ 3 V
2 V ≤ VIN ≤ 5 V
2 V ≤ VIN ≤ 9 V
VOUT
DUTY CYCLE
3.13
4.75
11.45
ADP1109A-3.3
ADP1109A-5
ADP1109A-12
OSCILLATOR FREQUENCY
Full Load
SWITCH-ON TIME
SWITCH SATURATION VOLTAGE
ADP1109A-3.3
ADP1109A-5
ADP1109A-12
ISW = 500 mA
VIN = 3 V
VIN = 3 V
VIN = 3 V
SWITCH LEAKAGE CURRENT
VSW = 9 V, TA = +25°C
Typ
Max
Units
460
580
µA
9
V
1.25
1.30
V
8
12.5
mV
3.30
5.00
12.00
3.47
5.25
12.55
V
V
V
15
25
60
35
50
120
mV
mV
mV
2
1.20
COMPARATOR HYSTERESIS
OUTPUT VOLTAGE RIPPLE
Min
fOSC
95
120
155
kHz
DC
57
67
77
%
tON
3.8
5.6
7.4
µs
0.4
0.4
0.4
0.8
0.8
0.8
V
V
V
1
10
µA
VCESAT
SHUTDOWN PIN HIGH
VIH
2.0
V
SHUTDOWN PIN LOW
VIL
0.8
V
SHUTDOWN PIN INPUT CURRENT
VSHUTDOWN = 4 V
IIH
10
µA
SHUTDOWN PIN INPUT CURRENT
VSHUTDOWN = 0 V
IIL
20
µA
NOTES
All limits at temperature extremes are guaranteed via correlation using standard quality control methods.
Specifications subject to change without notice.
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage, VOUT . . . . . . . . . . . . . . . . . . . . –0.4 V to 20 V
SW Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . –0.4 V to 50 V
Shutdown Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 V
Switch Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 A
Maximum Power Dissipation . . . . . . . . . . . . . . . . . . 300 mW
Operating Temperature Range . . . . . . . . . . . . 0°C to +70°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . +300°C
*This is a stress rating only; operation beyond these limits can cause the device to
be permanently damaged.
–2–
REV. 0
ADP1109A
PIN FUNCTION DESCRIPTIONS
PIN CONFIGURATIONS
Pin Mnemonic
Function
1
2
3
4
5
6
7
VIN
NC
SW
PGND
GND
NC
SHUTDOWN
8
FB(SENSE)
Input Supply Voltage.
No Connection.
Collector Node of Power Transistor.
Power Ground.
Ground.
No Connection.
When logic low is applied to this pin,
oscillator is shut down.
On the ADP1109A (Adjustable), this
pin goes directly to the comparator input.
On the ADP1109A-3.3, ADP1109A-5
and ADP1109A-12, this pin is connected
through the internal resistor that sets
the output voltage.
8-Lead Plastic DIP
(N-8)
Package
Description
Package
Options
ADP1109AAN
ADP1109AAR
ADP1109AAN-3.3
ADP1109AAR-3.3
ADP1109AAN-5
ADP1109AAR-5
ADP1109AAN-12
ADP1109AAR-12
ADJ
ADJ
3.3 V
3.3 V
5V
5V
12 V
12 V
Plastic DIP
Small Outline IC
Plastic DIP
Small Outline IC
Plastic DIP
Small Outline IC
Plastic DIP
Small Outline IC
N-8
SO-8
N-8
SO-8
N-8
SO-8
N-8
SO-8
ADP1109A
FB(SENSE)*
7
5
PGND 4
GND
*FIXED VERSIONS
NC = NO CONNECT
8-Lead SOIC
(SO-8)
VIN 1
8
FB(SENSE)*
NC 2
ADP1109A
7
SHUTDOWN
SW 3
TOP VIEW
(Not to Scale)
6
NC
5
GND
PGND 4
Output
Voltage
*FIXED VERSIONS
NC = NO CONNECT
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 ADP1109A 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
2
SHUTDOWN
TOP VIEW
SW 3 (Not to Scale) 6 NC
NC
ORDERING GUIDE
Model
8
VIN 1
–3–
WARNING!
ESD SENSITIVE DEVICE
ADP1109A
2kV
MBRS130T3
20mH*
VIN
3.3V
22mF
MBRS130T3
10mH*
12V
60mA
+
VIN
5V
22mF
2N4403
+
3
SW
VIN
1
3
SENSE 8
1
ADP1109A-12
4
5
7
+
SHUTDOWN
GND PGND
33mF**
25V
*COILTRONICS CTX33-2
SUMIDA CD54-330LC
**AVX TPS SERIES
**AVX TPS SERIES
Figure 1. 3.3 V Powered Flash Memory VPP Generator
+
1mF
L1
33mH*
MBRS130T3
12V
35mA
+
3
SW
VIN
1
3
VIN
3V
SENSE 8
ADP1109A-12
SHUTDOWN
GND PGND
7
4
5
1
SW
VIN
7
+ 33mF**
25V
SHUTDOWN
GND
GND
5
SHUTDOWN
FB 8
ADP1109A
4
R2
250kV
R1
+
40.3kV
VOUT
9V
C1
22mF**
16V
SHUTDOWN
*COILTRONICS CTX10-1
SUMIDA CD54-100LC
*COILTRONICS CTX33-2
SUMIDA CD54-330LC
**AVX TPS SERIES
**AVX TPS SERIES
Figure 2. 2 V Powered Flash Memory VPP Generator
Figure 5. 3 V to 9 V Converter
MBRS130T3
10mH*
22mF
47mF**
20V
Figure 4. 5 V to 12 V Converter With Shutdown to 0 V at
Output
MBRS130T3
10mH*
VIN
2V
+
SHUTDOWN
*COILTRONICS CTX20-1
SUMIDA CD54-220LC
22mF
4
5
SHUTDOWN
VIN
2V
VOUT
12V
110mA
SENSE 8
ADP1109A-12
SHUTDOWN
GND PGND
7
SW
VIN
5V
110mA
+
3
1
SW
VIN
SENSE 8
ADP1109A-5
7
SHUTDOWN
GND PGND
5
4
+ 33mF**
10V
SHUTDOWN
*COILTRONICS CTX10-1
SUMIDA CD54-100LC
**AVX TPS SERIES
Figure 3. 2 V to 5 V Converter
–4–
REV. 0
ADP1109A
68
110
90
25
70
TEMPERATURE – 8C
53
–40
85
0
Figure 7. Duty Cycle vs. Temperature
VCE(SAT) @ VIN = 3V AND ISW = 0.65A
SWITCH-ON TIME – msec
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0
25
70
TEMPERATURE – 8C
VIN = 2V
550
5.0
4.5
4.0
3.5
3.0
0
25
70
TEMPERATURE – 8C
85
QUIESCENT CURRENT – mA
12.00
11.95
11.90
11.85
11.80
500
400
300
11.75
0
25
70
TEMPERATURE – 8C
85
Figure 12. 12 V Output Voltage vs.
Temperature
200
1
1.2
500
450
400
350
2
4
6
8 10 12 14 16
INPUT VOLTAGE – Volts
18
20
Figure 13. Quiescent Current vs.
Input Voltage
–5–
250
–40
0
25
70
TEMPERATURE – 8C
85
Figure 11. Quiescent Current vs.
Temperature
600
12.05
0.4
0.6
0.8
ISWITCH CURRENT – A
300
12.15
12.10
0.2
Figure 8. Saturation Voltage vs.
ISWITCH Current in Step-Up Mode
5.5
Figure 10. Switch-On Time vs.
Temperature
12.20
OUTPUT VOLTAGE – V
0.4
600
2.0
–40
85
Figure 9. Switch Saturation Voltage
vs. Temperature
REV. 0
0.6
6.0
2.5
0.15
11.70
–40
VIN = 3V
0.8
0.0
0.1
85
25
70
TEMPERATURE – 8C
QUIESCENT CURRENT – mA
0
0.60
VCE(SAT) – V
59
VIN = 5V
1.0
0.2
Figure 6. Oscillator Frequency vs.
Temperature
0.10
–40
62
56
70
0.55
SATURATION VOLTAGE – V
65
130
50
–40
1.4
1.2
150
DUTY CYCLE – %
OSCILLATOR FREQUENCY – kHz
170
ADP1109A
considered for battery powered and similar applications where
the input voltage varies.
APPLICATION INFORMATION
THEORY OF OPERATION
The ADP1109A is a flexible, low power switch-mode power
supply (SMPS) controller for step-up dc/dc converter applications. This device uses a gated-oscillator technique to provide
very high performance with low quiescent current. For example,
more than 2 W of output power can be generated from a +5 V
source, while quiescent current is only 360 µA.
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 two step process:
1. Define the operating parameters: minimum input voltage,
maximum input voltage, output voltage and output current.
A functional block diagram of the ADP1109A is shown on the
front page. The internal 1.25 V 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
1.25 V, the 120 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 1.25 V, the oscillator is shut off. While the oscillator is
off, the ADP1109A quiescent current is only 460 µA. The comparator includes a small amount of hysteresis, which ensures
loop stability without requiring external components for frequency compensation.
2. Calculate the inductor value, using the equations in the following section.
Inductor Selection
In a step-up, or boost, converter (Figure 1), the inductor must
store enough power to make up the difference between the input
voltage and the output voltage. The inductor power is calculated
from the equation:
(
) ( )
P L = VOUT +V D −VIN ( MIN ) × IOUT
(1)
where VD is the diode forward voltage (<0.5 V for a 1N5818
Schottky). Energy is only stored in the inductor while the
ADP1109A switch is ON, so the energy stored in the inductor
on each switching cycle must be must be equal to or greater
than:
A shutdown feature permits the oscillator to be shut off. Holding SHUTDOWN low will disable the oscillator, and the
ADP1109A’s quiescent current will remain 460 µA.
The output voltage of the ADP1109A is set with two external
resistors. Three fixed-voltage models are also available: the
ADP1109A-3.3 (+3.3 V), ADP1109A-5 (+5 V) and ADP1109A-12
(+12 V). The fixed-voltage models are identical to the ADP1109A,
except that laser-trimmed voltage-setting resistors are included on
the chip. On the fixed-voltage models of the ADP1109A, simply
connect the SENSE pin (Pin 8) directly to the output voltage.
PL
f OSC
(2)
in order for the ADP1109A to regulate the output voltage. When
the internal power switch turns ON, current flow in the inductor
increases at the rate of:
COMPONENT SELECTION
General Notes on Inductor Selection
()
IL t =
When the ADP1109A 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.
− R't 
V IN 
1− e L 

R' 

(3)
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. In most applications, the voltage drop across the
switch is small compared to VIN so a simpler equation can be
used:
To specify an inductor for the ADP1109A, the proper values of
inductance, saturation current and dc resistance must be determined. This process is not difficult, and specific equations 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 VIN 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 ADP1109A applications, an
inductor of 10 µH to 47 µH, with a saturation current rating of
300 mA to 1 A and dc resistance <0.4 Ω is suitable. Ferrite core
inductors that meet these specifications are available in small,
surface-mount packages. Air-core inductors, as well as RF chokes,
are unsuitable because of their low peak current ratings.
()
IL t =
V IN
t
L
(4)
Replacing t in the above equation with the ON time of the
ADP1109A (5.5 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 = L × I 2 peak
2
The ADP1109A is designed for applications where the input
voltage is fairly stable, such as generating +12 V from a +5 V
logic supply. The ADP1109A does not have an internal switch
current limiting circuit, so the inductor may saturate if the input
voltage is too high. The ADP1111 or ADP3000 should be
–6–
(5)
As previously mentioned, EL must be greater than PL/fOSC so
that the ADP1109A 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.
REV. 0
ADP1109A
In practice, the inductor value is easily selected using the equations above. For example, consider a supply that will generate
12 V at 120 mA from a +5 V source. The inductor power required is, from Equation 1:
Capacitor Selection
For optimum performance, the ADP1109A’s output capacitor
must be carefully selected. Choosing an inappropriate capacitor
can result in low efficiency and/or high output ripple.
PL = (12 V + 0.5 V – 5 V) × (120 mA) = 900 mW
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.
On each switching cycle, the inductor must supply:
P L 900 mW
=
= 7.5 µJ
f OSC 120 kHz
The required inductor power is fairly low in this example, so
the peak current can also be low. Assuming a peak current of
600 mA as a starting point, Equation 4 can be rearranged to
recommend an inductor value:
L=
V IN
I L ( MAX )
t=
Diode Selection
5V
5.5 µs = 45.8 µH
600 mA
In specifying a diode, consideration must be given to speed,
forward voltage drop and reverse leakage current. When the
ADP1109A 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 VF must also be minimized. Again,
Schottky 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.
Substituting a standard inductor value of 33 µH, with 0.2 Ω dc
resistance, will produce a peak switch current of:
I PEAK =
5V
1.0 Ω
–1.0 Ω × 5.5 µs 

33 µH
1−
e

 = 768 mA


Once the peak current is known, the inductor energy can be
calculated from Equation 5:
EL =
(
) (
1
33 µH × 768 mA
2
)
2
For most circuits, the 1N5818 is a suitable companion to the
ADP1109A. This diode has a VF of 0.5 V at 1 A, 4 µA to 10 µA
leakage, and fast turn-on and turn-off times. A surface mount
version, the MBRS130T3, is also available.
= 9.7 µJ
The inductor energy of 9.7 µJ is greater than the PL/fOSC requirement of 7.5 µJ, so the 33 µH inductor will work in this
application. By substituting other inductor values into the same
equations, the optimum inductor value can be selected. When
selecting an inductor, the peak current must not exceed the
maximum switch current of 1.2 A. If the calculated peak current
is greater than 1.2 A, either the input voltage must be increased
or the load current decreased.
For switch currents of 100 mA or less, a Schottky diode such as
the BAT85 provides a VF of 0.8 V at 100 mA and leakage less
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 ADP1109A circuits. These devices, which have turn-on
times of 10 µs or more, are far too slow for switching power
supply applications. Using such a diode “just to get started” will
result in wasted time and effort. Even if an ADP1109A circuit
appears to function with a 1N4001, the resulting performance
will not be indicative of the circuit performance when the correct diode is used.
Output Voltage Selection
The output voltage is fed back to the ADP1109A via resistors
R1 and R2 (Figure 5). When the voltage at the comparator’s
inverting input falls below 1.25 V, the oscillator turns “on” and
the output voltage begins to rise. The output voltage is therefore
set by the formula:

R2 
VOUT = 1.25 V × 1+
R1 

Resistors R1 and R2 are provided internally on fixed-voltage
versions of the ADP1109A. In this case, a complete dc-dc converter requires only four external components.
REV. 0
–7–
ADP1109A
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP
(N-8)
0.1968 (5.00)
0.1890 (4.80)
0.430 (10.92)
0.348 (8.84)
8
5
0.280 (7.11)
0.240 (6.10)
4
PIN 1
0.210 (5.33)
MAX
0.060 (1.52)
0.015 (0.38)
0.160 (4.06)
0.115 (2.93)
0.022 (0.558) 0.100 0.070 (1.77)
0.014 (0.356) (2.54) 0.045 (1.15)
BSC
0.130
(3.30)
MIN
SEATING
PLANE
0.1574 (4.00)
0.1497 (3.80)
0.325 (8.25)
0.300 (7.62)
PIN 1
0.195 (4.95)
0.115 (2.93)
0.0098 (0.25)
0.0040 (0.10)
0.015 (0.381)
0.008 (0.204)
SEATING
PLANE
8
5
1
4
0.2440 (6.20)
0.2284 (5.80)
0.0688 (1.75)
0.0532 (1.35)
0.0500 0.0192 (0.49)
(1.27) 0.0138 (0.35)
BSC
0.0196 (0.50)
x 45°
0.0099 (0.25)
0.0098 (0.25)
0.0075 (0.19)
8°
0°
0.0500 (1.27)
0.0160 (0.41)
PRINTED IN U.S.A.
1
C3183–8–10/97
8-Lead SOIC
(SO-8)
–8–
REV. 0
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