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PDF PAM2301 Data sheet ( Hoja de datos )
| Número de pieza | PAM2301 | |
| Descripción | 800mA Step-Down DC-DC Converters | |
| Fabricantes | Power Analog Micoelectronics | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de PAM2301 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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Features
n Efficiency up to 96%
n Only 40μA(TYP.) Quiescent Current
n Output Current: Up to 800mA
n Internal Synchronous Rectifier
n 1.5MHz Switching Frequency
n Soft Start
n Under-Voltage Lockout
n Short Circuit Protection
n Thermal Shutdown
n 5-pin Small SOT23-5 Package
n Pb-Free Package
Applications
n Cellular Phone
n Portable Electronics
n Wireless Devices
n Cordless Phone
n Computer Peripherals
n Battery Powered Widgets
n Electronic Scales
n Digital Frame
Typical Application
www.DataSheet4U.com
Fixed Output Voltage
VIN
CIN
10μF
4 VIN
3 4.7μH
SW
1 EN
5
VOUT
GND
2
Vo
Co
10μF
PAM2301
800mA Step-Down DC-DC Converters
General Description
The PAM2301 is a step-down current-mode, DC-
DC converter. At heavy load, the constant-
frequency PWM control performs excellent
stability and transient response. To ensure the
longest battery life in portable applications, the
PAM2301 provides a power-saving Pulse-
Skipping Modulation (PSM) mode to reduce
quiescent current under light load operation to
save power.
The PAM2301 supports a range of input voltages
from 2.5V to 5.5V, allowing the use of a single
Li+/Li-polymer cell, multiple Alkaline/NiMH cell,
USB, and other standard power sources. The
output voltage is adjustable from 0.6V to the input
voltage, while the part number suffix PAM2301-
XX indicates pre-set output voltage of 3.3V, 2.8V,
2.5V, 1.8V, 1.5V, 1.2V or adjustable. All versions
employ internal power switch and synchronous
rectifierfor to minimize external part count and
realize high efficiency. During shutdown, the input
is disconnected from the output and the shutdown
current is less than 0.1μA. Other key features
include under-voltage lockout to prevent deep
battery discharge.
The PAM2301 is available in SOT23-5 package.
Adjustable Output Voltage
VIN
CIN
10μF
4 VIN
3 4.7μH
SW
1 EN
5
FB
GND
2
R1
R2
Vo
20pF Co
10μF
VO
=
0.6 ´
æçè1 +
R1
R2
ö
÷ø
Power Analog Microelectronics,Inc
www.poweranalog.com
1
09/2008 Rev 1.3
1 page  
PAM2301
800mA Step-Down DC-DC Converters
Typical Performance Characteristics
TA=25 OC, CIN=10μF, CO=10uF,L=4.7μH, unless otherwise noted.
Efficiency VS Output Current (Vo=1.2V)
100
90
80
70
60
50
40
30
Vin=2.7V
20 Vin=3.6V
10 Vin=4.2V
0
1 10 100 1000
Output Current(m A)
Efficiency VS Output Current (Vo=1.5V)
100
90
80
70
60
50
40
30
20
1
2.5V
3.6V
4.2V
10 100 1000
Output Current(mA)
Efficiency VS Output Current (Vo=1.8V)
100
90
80
70
60
50
40
30
20
www.DataS1heet4U.com
10 100
Output Current(mA)
2.5V
3.6V
4.2V
1000
Efficiency VS Output Current (Vo=2.5V)
100
90
80
70
60
50
40
30
20
1
3V
3.6V
4.2V
10 100 1000
Output Current(mA)
Efficiency VS Output Current (Vo=2.8V)
100
90
80
70
60
50
40
30
20
1
3V
3.6V
4.2V
10 100 1000
Output Current(mA)
Eifficiency VS Output Current (Vo=3.3V)
100
90
80
70
60
50
40
30 Vin=3.6V
20 Vin=4.2V
10 Vin=5.0V
0
1 10 100 1000
Output Current(mA)
Power Analog Microelectronics,Inc
www.poweranalog.com
5
09/2008 Rev 1.3
5 Page 
100% Duty Cycle Operation
As the input voltage approaches the output
voltage, the converter turns the P-channel
transistor continuously on. In this mode the
output voltage is equal to the input voltage minus
the voltage drop across the P - channel
transistor:
VOUT = VIN – ILOAD × (Rdson + RL)
where Rdson = P-channel switch ON resistance,
ILOAD = Output current, RL = Inductor DC
resistance
UVLO and Soft-Start
The reference and the circuit remain reset until
the VIN crosses its UVLO threshold.
The PAM2301 has an internal soft-start circuit
that limits the in-rush current during start-up.
This prevents possible voltage drops of the input
voltage and eliminates the output voltage
overshoot. The soft-start acts as a digital circuit
to increase the switch current in several steps to
the P-channel current limit (1500mA).
Short Circuit Protection
The switch peak current is limited cycle-by-cycle
to a typical value of 1500mA. In the event of an
output voltage short circuit, the device operates
with a frequency of 400kHz and minimum duty
cycle, therefore the average input current is
wwwty.DpaitcaSahlleyet240U.0cmomA.
Thermal Shutdown
When the die temperature exceeds 150°C, a
reset occurs and the reset remains until the
temperature decrease to 120°C, at which time
the circuit can be restarted.
PAM2301
800mA Step-Down DC-DC Converters
PCB Layout Check List
When laying out the printed circuit board, the
following checklist should be used to ensure
proper operation of the PAM2301. These items
are also illustrated graphically in Figure 1. Check
the following in your layout:
1. The power traces, consisting of the GND
trace, the SW trace and the VIN trace should be
kept short, direct and wide.
2. Does the VFB pin connect directly to the
feedback resistors? The resistive divider R1/R2
must be connected between the (+) plate of COUT
and ground.
3. Does the (+) plate of CIN connect to VIN as
closely as possible? This capacitor provides the
AC current to the internal power MOSFETs.
4. Keep the switching node, SW, away from the
sensitive VFB node.
5. Keep the (–) plates of CIN and COUT as close
as possible.
Figure 1 :PAM2301 Suggested Layout
Power Analog Microelectronics,Inc
www.poweranalog.com
11
09/2008 Rev 1.3
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet PAM2301.PDF ] | |
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