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PDF AMS1505CM-50 Data sheet ( Hoja de datos )
| Número de pieza | AMS1505CM-50 | |
| Descripción | 5A LOW DROPOUT VOLTAGE REGULATORS | |
| Fabricantes | Advanced Monolithic Systems | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AMS1505CM-50 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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Advanced
Monolithic
Systems
AMS1505
5A LOW DROPOUT VOLTAGE REGULATORS
FEATURES
• Adjustable or Fixed Output
1.5V, 2.5V, 2.85V, 3.0V, 3.3V, 3.5V and 5.0V
• Output Current of 5A
• Low Dropout, 500mV at 5A Output Current
• Fast Transient Response
• Remote Sense
APPLICATIONS
• High Current Regulators
• Post Regulators for Switching Supplies
• Microprocessor Supply
• Adjustable Power Supply
• Notebook/Personal Computer Supplies
GENERAL DESCRIPTION
TThhee AMS1505 series of adjustable and fixed low dropout voltage regulators are designed to provide 5A output current to
power the new generation of microprocessors. The dropout voltage of the device is 100mV at light loads and rising to 500mV
at maximum output current. A second low current input voltage 1V or greater then the output voltage is required to achieve
this dropout. The AMS1505 can also be used as a single supply device.
New features have been added to the AMS1505: a remote Sense pin is brought out virtually eliminating output voltage
variations due to load changes. The typical load regulation, measured at the Sense pin, for a load current step of 100mA to 5A
is less than 1mV.
The AMS1505 series has fast transient response. The Adjust pin is brought out on fixed devices. To further improve the
transient response the addition of a small capacitor on the Adjust pin is recommended.
The AMS1505 series are ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V
supplies are available.
The AMS1505 devices are offered in 5 lead TO-220 and TO-263 (plastic DD) packages and in the 7 lead TO-220 package.
ORDERING INFORMATION:
PACKAGE TYPE
OPERATING JUNCTION
5 LEAD TO-263 5 LEAD TO-220 7 LEAD TO-220 TEMPERATURE RANGE
AMS1505CM AMS1505CT
AMS1505CT-1.5
AMS1505CM-1.5 AMS1505CT-1.5 AMS1505CT-2.5
AMS1505CM-2.5 AMS1505CT-2.5 AMS1505CT-2.85
AMS1505CM-2.85 AMS1505CT-2.85 AMS1505CT-3.0
AMS1505CM-3.0 AMS1505CT-3.0 AMS1505CT-3.3
AMS1505CM-3.3 AMS1505CT-3.3 AMS1505CT-3.5
AMS1505CM-3.5 AMS1505CT-3.5 AMS1505CT-5.0
AMS1505CM-5.0 AMS1505CT-5.0
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
0 to 125° C
PIN CONNECTIONS
5 LEAD TO-220
5
4
3
2
1
FRONT VIEW
VPOWER
VCONTROL
OUTPUT
ADJUST/GND
SENSE
7 LEAD TO-220
7
6
5
4
3
2
1
FRONT VIEW
NC
Vpower
ADJUST
OUTPUT
Vcontrol
GND
SENSE
5 LEAD TO-263
5 Vpower
4 Vcontrol
3 OUTPUT
2 ADJUST/GND
1 SENSE
FRONT VIEW
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
1 page  
AMS1505
APPLICATION HINTS
5V
3.3V
CONTROL
POWER SENSE
AMS1505
OUTPUT
ADJ
R1
R2
RP
LOAD
RP
+
VOUT
-
Figure 2. Remote Load Sensing
VOUT
FIGURE 1
VOUT
FIGURE 2
(∆IOUT)(RP)
to allow this capability. To ensure good transient response with
heavy load current changes capacitor values on the order of
100µF are used in the output of many regulators. To further
improve stability and transient response of these devices larger
values of output capacitor can be used.
The modern processors generate large high frequency current
transients. The load current step contains higher order frequency
components than the output coupling network must handle until
the regulator throttles to the load current level. Because they
contain parasitic resistance and inductance, capacitors are not
ideal elements. These parasitic elements dominate the change in
output voltage at the beginning of a transient load step change.
The ESR of the output capacitors produces an instantaneous step
in output voltage (∆V=∆I)(ESR). The ESL of the output
capacitors produces a droop proportional to the rate of change of
the output current (V= L)(∆I/∆t). The output capacitance
produces a change in output voltage proportional to the time until
the regulator can respond (∆V=∆t) (∆I/C). Figure 4 illustrates
these transient effects.
ESR
EFFECTS
ESL
EFFECTS
CAPACITANCE
EFFECTS
IOUT
TIME
Figure 3. Remote Sensing Improves Load Regulation
Voltage drops due to RP are not eliminated; they will add to the
dropout voltage of the regulator regardless of whether they are
inside or outside the regulation loop. The AMS1505 can control
the voltage at the load as long as the input-output voltage is
greater than the total of the dropout voltage of the device plus the
voltage drop across RP.
Stability
The circuit design used in the AMS1505 series requires the use of
an output capacitor as part of the device frequency compensation.
The addition of 150µF aluminum electrolytic or a 22µF solid
tantalum on the output will ensure stability for all operating
conditions. For best frequency response use capacitors with an
ESR of less than 1Ω.
In order to meet the transient requirements of the processor larger
value capacitors are needed. Tight voltage tolerances are required
in the power supply. To limit the high frequency noise generated
by the processor high quality bypass capacitors must be used. In
order to limit parasitic inductance (ESL) and resistance (ESR) in
the capacitors to acceptable limits, multiple small ceramic
capacitors in addition to high quality solid tantalum capacitors are
required.
When the adjustment terminal is bypassed to improve the ripple
rejection, the requirement for an output capacitor increases. The
Adjust pin is brought out on the fixed voltage device specifically
SLOPE, V/t = ∆I/C
POINT AT WHICH REGULATOR
TAKES CONTROL
Figure 4.
Output Voltage
The AMS1505 series develops a 1.25V reference voltage
between the Sense pin and the Adjust pin (Figure5). Placing a
resistor between these two terminals causes a constant current to
flow through R1 and down through R2 to set the overall output
voltage. In general R1 is chosen so that this current is the
specified minimum load current of 10mA.The current out of the
Adjust pin is small, typically 50µA and it adds to the current
from R1. Because IADJ is very small it needs to be considered
only when very precise output voltage setting is required. For
best regulation the top of the resistor divider should be connected
directly to the Sense pin.
VCONTROL
+
VPOWER
+
CONTROL
POWER OUTPUT
AMS1505
SENSE
ADJ
IADJ
50µA
VREF
VOUT = VREF (1+ R2/R1)+IADJR2
+
R1
R2
VOUT
Figure 5. Setting Output Voltage
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet AMS1505CM-50.PDF ] | |
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