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ADP2109 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADP2109
Beschreibung Step-Down Converter
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 16 Seiten
ADP2109 Datasheet, Funktion
Data Sheet
Compact 600 mA, 3 MHz, Step-Down
Converter with Output Discharge
ADP2109
FEATURES
Peak efficiency: 95%
Discharge switch function
Fixed frequency operation: 3 MHz
Typical quiescent current: 18 μA
Maximum load current: 600 mA
Input voltage: 2.3 V to 5.5 V
Uses tiny multilayer inductors and capacitors
Current mode architecture for fast load and line transient
response
100% duty-cycle low dropout mode
Internal synchronous rectifier
Internal compensation
Internal soft start
Current overload protection
Thermal shutdown protection
Shutdown supply current: 0.2 μA
5-ball WLCSP
Supported by ADIsimPower™ design tool
APPLICATIONS
PDAs and palmtop computers
Wireless handsets
Digital audio, portable media players
Digital cameras, GPS navigation units
GENERAL DESCRIPTION
The ADP2109 is a high efficiency, low quiescent current step-
down dc-to-dc converter with an internal discharge switch that
allows automatic discharge of the output capacitor in an ultra-
small 5-ball WLCSP package.
The total solution requires only three tiny external components.
It uses a proprietary high speed current mode and constant
frequency pulse-width modulation (PWM) control scheme for
excellent stability, and transient response. To ensure the longest
battery life in portable applications, the ADP2109 has a power
save mode that reduces the switching frequency under light
load conditions.
The ADP2109 runs on input voltages of 2.3 V to 5.5 V, which
allow for single lithium or lithium polymer cell, multiple alkaline
or NiMH cells, PCMCIA, USB, and other standard power
sources. The maximum load current of 600 mA is achievable
across the input voltage range.
The ADP2109 is available in fixed output voltages of 1.8 V, 1.5 V,
1.2 V, and 1.0 V. All versions include an internal power switch
and synchronous rectifier for minimal external part count and
high efficiency. The ADP2109 has an internal soft start and internal
compensation. During logic-controlled shutdown, the input is
disconnected from the output and the ADP2109 draws less than
1 μA from the input source.
Other key features include undervoltage lockout to prevent deep
battery discharge and soft start to prevent input current overshoot
at startup. The ADP2109 is available in a 5-ball WLCSP.
A similar converter, the ADP2108, provides the same features
and operations as the ADP2109 without the discharge switch
and is available in both WLCSP and TSOT packages with
additional output voltages.
TYPICAL APPLICATIONS CIRCUIT
2.3V TO 5.5V
4.7µF
VIN
1µH 1.0V TO 1.8V
SW
10µF
ADP2109
ON
OFF
EN FB
GND
Figure 1.
Rev. B
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityisassumedbyAnalogDevices for itsuse,nor foranyinfringementsofpatentsor other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2009–2012 Analog Devices, Inc. All rights reserved.
Free Datasheet http://www.datasheet4u.com/






ADP2109 Datasheet, Funktion
ADP2109
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 3.6 V, TA = 25°C, VEN = VIN, unless otherwise noted.
24
+85°C
22
20
+25°C
18
–40°C
16
14
12
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
Figure 3. Quiescent Supply Current vs. Input Voltage
3500
3400
3300
3200
3100
3000
2900
2800
2700
2600
2500
2.3
–40°C
+25°C
+85°C
2.8 3.3 3.8 4.3 4.8
INPUT VOLTAGE (V)
5.3
Figure 4. Switching Frequency vs. Input Voltage
1.840
1.835
1.830
1.825
1.820
1.815
1.810
1.805
1.800
1.795
–45
–25
IOUT = 10mA
IOUT = 150mA
IOUT = 500mA
–5 15 35
TEMPERATURE (°C)
55
75
Figure 5. Output Voltage vs. Temperature
Data Sheet
1400
1300
1200
1100
1000
900
800
700
600
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE (V)
Figure 6. PMOS Current Limit vs. Input Voltage
0.15
0.14
0.13
0.12
0.11
0.10
0.09
0.08
0.07
–40°C
0.06
0.05
+85°C
0.04
2.5
3.0
PWM TO PSM
PSM TO PWM
3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
Figure 7. Mode Transition Across Temperature
0.15
0.14
0.13
0.12
0.11
0.10
0.09
0.08
0.07
PSM TO PWM
PWM TO PSM
0.06
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
Figure 8. Mode Transition
Rev. B | Page 6 of 16
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ADP2109 pdf, datenblatt
ADP2109
APPLICATIONS INFORMATION
ADISIMPOWER DESIGN TOOL
The ADP2109 is supported by ADIsimPower design tool set.
ADIsimPower is a collection of tools that produce complete power
designs optimized for a specific design goal. The tools enable
the user to generate a full schematic, bill of materials, and calculate
performance in minutes. ADIsimPower can optimize designs for
cost, area, efficiency, and parts count while taking into consideration
the operating conditions and limitations of the IC and all real
external components. For more information about ADIsimPower
design tools, refer to www.analog.com/ADIsimPower. The tool
set is available from this website, and users can also request an
unpopulated board through the tool.
EXTERNAL COMPONENT SELECTION
Parameters like efficiency and transient response can be
affected by varying the choice of external components in
the applications circuit, as shown in Figure 1.
Inductor
The high switching frequency of the ADP2109 allows for the
selection of small chip inductors. For best performance, use
inductor values between 0.7 μH and 3 μH. Recommended
inductors are shown in Table 6.
The peak-to-peak inductor current ripple is calculated using
the following equation:
I RIPPLE
=
VOUT × (VIN VOUT )
VIN × fSW × L
where:
fSW is the switching frequency.
L is the inductor value.
The minimum dc current rating of the inductor must be greater
than the inductor peak current. The inductor peak current is
calculated using the following equation:
I PEAK
=
I LOAD(MAX)
+
I RIPPLE
2
Inductor conduction losses are caused by the flow of current
through the inductor, which has an associated internal DCR.
Larger sized inductors have smaller DCR, which may decrease
inductor conduction losses. Inductor core losses are related to
the magnetic permeability of the core material. Because the
ADP2109 is a high switching frequency dc-to-dc converter,
shielded ferrite core material is recommended for its low core
losses and low EMI.
Table 6. Suggested 1.0 μH Inductors
Vendor Model
Dimensions
Murata LQM2HPN1R0M 2.5 × 2.0 × 1.1
Coilcraft LPS3010-102 3.0 × 3.0 × 0.9
Toko
MDT2520-CN 2.5 × 2.0 × 1.2
TDK CPL2512T
2.5 × 1.5 × 1.2
ISAT (mA)
1500
1700
1800
1500
DCR (mΩ)
90
85
100
100
Data Sheet
Output Capacitor
Higher output capacitor values reduce the output voltage ripple
and improve load transient response. When choosing this value,
it is also important to account for the loss of capacitance due to
output voltage dc bias.
Ceramic capacitors are manufactured with a variety of dielectrics,
each with a different behavior over temperature and applied
voltage. Capacitors must have a dielectric that is adequate to
ensure the minimum capacitance over the necessary temper-
ature range and dc bias conditions. X5R or X7R dielectrics
with a voltage rating of 6.3 V or 10 V are recommended for
best performance. Y5V and Z5U dielectrics are not recom-
mended for use with any dc-to-dc converter because of their
poor temperature and dc bias characteristics.
The worst-case capacitance accounting for capacitor variation
over temperature, component tolerance, and voltage is
calculated using the following equation:
CEFF = COUT × (1 – TEMPCO) × 1(1 – TOL)
where:
CEFF is the effective capacitance at the operating voltage.
TEMPCO is the worst-case capacitor temperature coefficient.
TOL is the worst-case component tolerance.
In this example, the worst-case temperature coefficient (TEMPCO)
over −40°C to +85°C is assumed to be 15% for an X5R dielectric.
The tolerance of the capacitor (TOL) is assumed to be 10%, and
COUT is 9.2481 μF at 1.8 V from the graph in Figure 28.
Substituting these values in the equation yields
CEFF = 9.2481 μF × (1 – 0.15) × (1 – 0.1) = 7.0747 μF
To guarantee the performance of the ADP2109, it is imperative
that the effects of dc bias, temperature, and tolerances on the
behavior of the capacitors be evaluated for each application.
12
10
8
6
4
2
0
0123456
DC BIAS VOLTAGE (V)
Figure 28. Typical Capacitor Performance
Rev. B | Page 12 of 16
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