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PDF APW7290 Data sheet ( Hoja de datos )
| Número de pieza | APW7290 | |
| Descripción | 1A Synchronous Buck Regulator | |
| Fabricantes | ANPEC | |
| Logotipo |  |
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APW7290
1.5MHz, 1A Synchronous Buck Regulator
Features
General Description
• 1A Output Current
• Support 4 AA alkaline, NiCd or NiMH batteries
• Wide 3.5V~7.2V Input Voltage
• Fixed 1.5MHz Switching Frequency
• Low Dropout Operating at 100% duty cycle
• Low 25µA Quiescent Current
• Integrate Synchronous Rectifier
• 0.6V Low Reference Voltage
• <0.5µA Input Current during Shutdown
• Current-Mode Operation with Internal
Compensation
- Stable with Ceramic Output Capacitors
- Fast Line Transient Response
• Short-Circuit Protection
• Over-Temperature Protection with Hysteresis
• Available in TDFN2x2-8 Package
• Lead Free and Green Devices Available
(RoHS Compliant)
Applications
• E-Book
• Toy
• Portable Instrument
The APW7290 is a high efficiency monolithic synchro-
nous buck regulator. APW7290 operates with a constant
1.5MHz switching frequency and using the inductor cur-
rent as a controlled quantity in the current mode
architecture. The 3.5V to 7.2V input voltage range makes
the APW7290 ideally suited for single Li-Ion battery pow-
ered applications. 100% duty cycle provides low dropout
operation, extending battery life in portable electrical
devices. The internally fixed 1.5MHz operating frequency
allows the use of small surface mount inductors and
capacitors. The synchronous switches included inside
increase the efficiency and eliminate the need for an ex-
ternal Schottky diode.
The APW7290 is available in TDFN2x2-8 package.
Pin Configuration
GND 1
VIN 2
RUN 3
LBI 4
8 LBO
7 SW
6 VOUT
5 FB
TDFN2x2-8
(Top View)
Simplified Application Circuit
1 GND
Low Battery
Output
R3
VIN
C1
ON
OFF
2 VIN
LBO 8
3 RUN
SW 7
VOUT 6
R4 4 LBI
FB 5
R5 APW7290
L1
R1
R2
VOUT
C2
ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and
advise customers to obtain the latest version of relevant information to verify before placing orders.
Copyright © ANPEC Electronics Corp.
Rev. A.2 - Jun., 2013
1
www.anpec.com.tw
1 page  
APW7290
Typical Operating Characteristics
Vin Input Voltage vs. Quiescent
Current
40
35
30
25
20
15
10
5
0
3 3.5 4 4.5 5 5.5 6 6.5 7
Vin Input Voltage (V)
Temperature vs. Feedback Voltage
0.62
0.615
0.61
0.605
0.6
0.595
0.59
0.585
0.58
-60 -40 -20
0 20 40 60 80 100 120 140
Temperature (oC)
100.0
Io vs. Efficiency
95.0
90.0
85.0
80.0
75.0
70.0
65.0
60.0
Vo=3V,L=2.2uH,Cin=10u
55.0 F,Co=10uF
Vin=4V
Vin=5.5V
Vin=7V
50.0
0 100 200 300 400 500 600 700 800 900 1000
Io(mA)
Copyright © ANPEC Electronics Corp.
Rev. A.2 - Jun., 2013
5
Vin Input Voltage vs. Shutdown
Current
1
0.8
0.6
0.4
0.2
0
3 3.5 4 4.5 5 5.5 6 6.5 7
Vin Input Voltage (V)
Temperature vs. Frequency
1.8
1.7
1.6
1.5
1.4
1.3
1.2
-40 -20
0 20 40 60 80 100 120 140
Temperature (oC)
www.anpec.com.tw
5 Page 
APW7290
Application Information
Input Capacitor Selection
Because buck converters have a pulsating input current,
a low ESR input capacitor is required. This results in the
best input voltage filtering, minimizing the interference
with other circuits caused by high input voltage spikes.
Also, the input capacitor must be sufficiently large to sta-
bilize the input voltage during heavy load transients. For
good input voltage filtering, usually a 4.7µF input capaci-
tor is sufficient. It can be increased without any limit for
better input-voltage filtering. Ceramic capacitors show
better performance because of the low ESR value, and
they are less sensitive against voltage transients and
spikes compared to tantalum capacitors. Place the input
capacitor as close as possible to the input and GND pin of
the device for better performance.
shown in “Typical Application Circuits”. A suggestion of
maximum value of R2 is 200kΩ to keep the minimum
current that provides enough noise rejection ability through
the resistor divider. The output voltage can be calculated
as below:
VOUT
=
VREF
⋅ 1+
R1
R2
=
0.6 ⋅ 1+
R1
R2
VOUT
FB
APW7290
GND
R1≤1MΩ
R2 ≤ 200kΩ
Inductor Selection
For high efficiencies, the inductor should have a low DC
resistance to minimize conduction losses. Especially at
high-switching frequencies, the core material has a
higher impact on efficiency. When using small chip
inductors, the efficiency is reduced mainly due to higher
inductor core losses. This needs to be considered when
selecting the appropriate inductor. The inductor value de-
termines the inductor ripple current. The larger the induc-
tor value, the smaller the inductor ripple current and the
lower the conduction losses of the converter. Conversely,
larger inductor values cause a slower load transient
response. A reasonable starting point for setting ripple
current, ∆IL, is 40% of maximum output current. The rec-
ommended inductor value can be calculated as below:
L
≥
VOUT 1−
VOUT
VIN
FSW ⋅ ∆IL
I
L(MAX)
=
I
OUT(MAX)
+
1/2
x
∆IL
To avoid the saturation of the inductor, the inductor should
be rated at least for the maximum output current of the
converter plus the inductor ripple current.
Output Voltage Setting
In the adjustable version, the output voltage is set by a
resistive divider. The external resistive divider is con-
nected to the output, allowing remote voltage sensing as
Output Capacitor Selection
The current-mode control scheme of the APW7290 al-
lows the use of tiny ceramic capacitors. The higher ca-
pacitor value provides the good load transients response.
Ceramic capacitors with low ESR values have the lowest
output voltage ripple and are recommended. If required,
tantalum capacitors may be used as well. The output
ripple is the sum of the voltages across the ESR and the
ideal output capacitor.
∆VOUT
≅
VOUT
⋅ 1−
VOUT
VIN
FSW ⋅ L
⋅ ESR +
1
8 ⋅ FSW ⋅ COUT
When choosing the input and output ceramic capacitors,
choose the X5R or X7R dielectric formulations. These
dielectrics have the best temperature and voltage char-
acteristics of all the ceramics for a given value and size.
VIN IIN
IP-FET
IL
CIN P-FET
SW
N-FET
IOUT VOUT
ESR
COUT
Copyright © ANPEC Electronics Corp.
Rev. A.2 - Jun., 2013
11
www.anpec.com.tw
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet APW7290.PDF ] | |
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