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ADP3607ARU-5 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADP3607ARU-5
Beschreibung 50 mA Switched Capacitor Voltage Boost with Regulated Output
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 8 Seiten
ADP3607ARU-5 Datasheet, Funktion
a
50 mA Switched Capacitor
Voltage Boost with Regulated Output
ADP3607
FEATURES
Fully Regulated Output Voltage (5 V and Adjustable)
Input Voltage Range From 3 V to 5 V
50 mA Output Current
Output Accuracy: ؎5%
High Switching Frequency: 250 kHz
SO-8 and TSSOP-8 Packages
–40؇C to +85؇C Ambient Temperature Range
APPLICATIONS
Computer Peripherals and Add-On Cards
Portable Instruments
Battery Powered Devices
Pagers and Radio Control Receivers
Disk Drives
Mobile Phones
FUNCTIONAL BLOCK DIAGRAM
CP+
CP
S1
VIN
S3
S4
S2 VOUT
OSC
SD CLOCK
GEN
1.5 V
VREF
FB
VSENSE
GENERAL DESCRIPTION
The ADP3607 is a 50 mA regulated output switched capacitor
voltage doubler. It provides a regulated output voltage with
minimum voltage loss and requires a minimum number of ex-
ternal components. In addition, the ADP3607 does not require
the use of an inductor.
The internal oscillator of the ADP3607 runs at 500 kHz nomi-
nal frequency, which produces an output switching frequency of
250 kHz. This allows for the use of smaller charge pump and
filter capacitors.
The ADP3607 provides an accuracy of ± 5% with a typical shut-
down current of 150 µA. It can also operate from a single posi-
tive input voltage as low as 3 V. The ADP3607 is offered with
the regulation fixed at 5 V, or adjustable via external resistors
over a 3 V to 9 V range.
GND
SD103
VIN
3.3V *CIN+
4.7F
* CP
4.7F
+
D1
VIN
CP+
VOUT
ADP3607-5
VOUT
+
5.0V
* CO
4.7F
CP
OFF
SD
ON
0
GND
VSENSE
*FOR BEST PERFORMANCE, 10F IS RECOMMENDED
CP : SPRAGUE, 293D475X0010B2W
CIN, CO: TOKIN, 1E475ZY5UC205F
Figure 1. Typical Application Circuit
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., 1999






ADP3607ARU-5 Datasheet, Funktion
ADP3607
THEORY OF OPERATION
The ADP3607 uses a switched capacitor principle to generate
a regulated boost voltage from a positive input voltage. An
on-board oscillator generates a two-phase clock to control a
switching network that transfers charge between the storage
capacitors. The switches turn on and off at a 250 kHz rate that
is generated from an internal 500 kHz oscillator. The basic
principle behind the voltage conversion scheme is illustrated in
Figures 14 and 15.
S1
VIN
S2
+
CP
S4 S3
VOUT
Figure 14. ADP3607 Switch Configuration Charging the
Pump Capacitor
During phase one, S1 and S3 are ON, charging the pump ca-
pacitor to the input voltage. Before the next phase begins, S1
and S3 are turned OFF, as are S2 and S4 to prevent any over-
lap. S2 and S4 are turned ON during the second phase (see
Figure 15) and charge stored in the pump capacitor is trans-
ferred to the output capacitor.
When selecting the capacitors, keep in mind that not all manu-
facturers guarantee capacitor ESR in the range required by the
circuit. In general, the capacitor’s ESR is inversely proportional
to its physical size, so larger capacitance values and higher volt-
age ratings tend to reduce ESR. Since the ESR is also a function
of the operating frequency, when selecting a capacitor make sure
its value is rated at the circuit’s operating frequency. Another
factor affecting capacitor performance is temperature.
Figure 16 illustrates the temperature effect on various capaci-
tors. If the circuit has to operate at temperatures significantly
different from +25°C, the capacitance and ESR values must be
carefully selected to adequately compensate for the change.
Various capacitor technologies offer improved performance over
temperature; for example, certain tantalum capacitors provide
good low temperature ESR but at a higher cost. Table II pro-
vides the ratings for different types of capacitor technologies to
help the designer select the right capacitors for the application.
The exact values of CIN and CO are not critical. However, low
ESR capacitors such as solid tantalum and multilayer ceramic
capacitors are recommended to minimize voltage loss at high
currents. Table III shows a partial list of the recommended low
ESR capacitor manufacturers.
S1
VIN
S2
+
CP
S4 S3
VOUT
Figure 15. ADP3607 Switch Configuration Charging the
Output Capacitor
During the second phase, the negative terminal of the pump
capacitor is connected to VIN through variable resistance switch
S4, and the positive terminal is connected to the output, result-
ing in a voltage shift at the output terminal. The ADP3607
block diagram is shown on the front page.
10
ALUMINUM
1.0
CERAMIC
TANTALUM
0.1
ORGANIC SEMIC
40
ADP3607-5
35
30
ILOAD = 50mA
25
20
150m
15
100m
10
50m
5
0 20 40 60 80 100 120 140
CAPACITANCE – F
Figure 17. Output Ripple Voltage (mV) vs. Capacitance
and ESR
Input Capacitor
A small 1 µF input bypass capacitor (preferably with low ESR)
such as tantalum or multilayer ceramic, is recommended to
reduce noise and supply transients, and supply part of the peak
input current drawn by the ADP3607. A large capacitor is rec-
ommended if the input supply is connected to the ADP3607
through long leads, or if the pulse current drawn by the device
might affect other circuitry through supply coupling.
0.01
–50
0 50
TEMPERATURE – ؇C
Figure 16. ESR vs. Temperature
100
APPLICATION INFORMATION
Capacitor Selection
The ADP3607’s high internal oscillator frequency permits the
use of small capacitors for both the pump and the output ca-
pacitors. For a given load current, factors affecting the output
voltage performance are:
• Pump (CP) and output (CO) capacitance.
• ESR of the CP and CO.
Output Capacitor
The output capacitor (CO) is alternately charged to the CP volt-
age when CP is switched in parallel with CO. The ESR of CO
introduces steps in the VOUT waveform whenever the charge
pump charges CO, which contributes to VOUT ripple. Thus,
ceramic or tantalum capacitors are recommended for CO to
minimize ripple on the output. Figure 17 illustrates the output
ripple voltage effect for various capacitance and ESR values.
Note that as the capacitor value increases beyond the point
where the dominant contribution to the output ripple is due to
the ESR, no significant reduction in VOUT ripple is achieved by
added capacitance. Since output current is supplied solely by
–6– REV. 0

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