ET-AMS1084M-XX [ESTEK]
LOW DROPOUT POSITIVE VOLTAGE; 低压差正电压
| 型号： | ET-AMS1084M-XX |
| 厂家： | 
Estek Electronics Co. Ltd |
| 描述： | LOW DROPOUT POSITIVE VOLTAGE |
| 文件： | 总3页 (文件大小：412K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
September 2005
Inv № 400
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ET- AMS1084M-XX
REGULATOR
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DESCRIPTION
The AMS1084M series of positive adjustable and fixed regulators are designed to provide 5A with high efficiency. All internal
circuitry is designed to operate down to 1.3V input to output differential. On-chip trimming adjusts the reference voltage to
1%.
APPLICATIONS
•
•
•
High Efficiency Linear Regulators
Post Regulators for Switching Supplies
Adjustable Power Supply
FEATURES
•
•
•
•
•
•
•
Adjustable or Fixed Output
Output Current of 5A
Low Dropout, 1.5V max at 5A Output Current
0.04% Line Regulation
0.2 % Load Regulation
100% Thermal Limit Burn-In
Fast Transient Response
TYPICAL APPLICATION DATA
4.95V
4.8V
AMS1084M
AMS1084M-3.3
PIN DESCRIPTION
BEIJING ESTEK ELECTRONICS CO.,LTD
Page 1 of 3
ET- AMS1084M-XX
ABSOLUTE MAXIMUM RATINGS
SYMBOL
VCC
PARAMETER
VALUE
UNIT
W
Power Dissipation
Input Voltage
Internally Limited
15
VIN
V
Operation Junction Temperature Range
Control Section
TJ
0 to 125
0 to 150
-65 to +150
300
0C
Power Transistor
TSTG
TLEAD
Storage Temperature Range
Lead Temperature (Soldering 10 sec)
0C
0C
ELECTRICAL CHARACTERISTICS
ILOAD = 0mA and TJ = +25 0C (unless otherwise noted)
PARAMETER
DEVICE
TEST CONDITIONS
MIN.
TYP.
MAX.
UNIT
VIN =5V, ILOAD = 10mA
1.238
1.225
1.250
1.250
1.262
1.275
Reference Voltage Note 1 AMS1084M
V
VIN – VOUT = 1.5V to 10V,
*
ILOAD = 10mA to 5A
VIN – VOUT = 1.5V,
-1
-2
-
-
-
+1
+2
Variator from nominal VOUT
All fixed
Output Voltage Note 1
versions
%
VIN – VOUT = 1.5V to 10V
ILOAD = 0mA to 5A,
*
*
Variator from nominal VOUT
I
LOAD = 10mA,
Line Regulation Note 1
All
All
0.04
0.20
VIN – VOUT = 1.5V to 10V
VIN – VOUT = 1.5V
%
Load Regulation Note 1
Minimum Load Current
Ground Pin Current
*
*
*
-
-
-
0.2
3
0.40
7
I
LOAD = 10mA to 5A
AMS1084M VIN =5V, VADJ = 0V
mA
mA
VIN – VOUT = 1.5V
ILOAD = 10mA to 5A
All fixed
7
10
versions
V
IN – VOUT = 1.5V to 10V
Adjust Pin Current
AMS1084M
*
*
*
*
*
-
5
60
-
40
6.5
90
µA
A
ILOAD = 10mA
Current Limit
All
All
All
All
VIN – VOUT = 1.5V
VIN – VOUT = 3V
ILOAD = 5A
-
-
Ripple Rejection Note 2
Dropout Voltage Note 1,3
Temperature Coefficient
72
dB
ILOAD = 5A
1.3
1.5
-
V
%/0C
V
IN – VOUT = 1.5V,
-
0.005
ILOAD = 10mA
The * denotes the specifications which apply over the full temperature range (see previous table, TJ)
NOTES:
1: Low duty pulse testing with Kelvin connections required.
2: 120Hz input ripple (CADJ for ADJ = 25µF, COUT = 25µF)
3: ∆VOUT, ∆VREF = 1%
APPLICATION INFORMATION
The AMS1084M series of adjustable and fixed regulators are easy to use and have all the protection features expected in
high performance voltage regulators: short circuit protection and thermal shut-down.
Pin compatible with older three terminal adjustable regulators, these devices offer the advantage of a lower dropout voltage,
more precise reference tolerance and improved reference stability with temperature.
STABILITY
The circuit design used in the AMS1084M 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.
When the adjustment terminal is bypassed with a capacitor to improve the ripple rejection, the requirement for an output
capacitor increases. The value of 22µF tantalum or 150µF aluminum covers all cases of bypassing the adjustment terminal.
Without bypassing the adjustment terminal smaller capacitors can be used with equally good results.
BEIJING ESTEK ELECTRONICS CO.,LTD
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ET- AMS1084M-XX
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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.
PROTECTION DIODES
Unlike older regulators, the AMS1084M family does not need any protection diodes
between the adjustment pin and the output and from the output to the input to
prevent over-stressing the die.
AMS1084M
Internal resistors are limiting the internal current paths on the AMS1084M
adjustment pin, therefore even with capacitors on the adjustment pin no protection
diode is needed to ensure device safety under short-circuit conditions.
Diodes between the input and output are not usually needed.
Microsecond surge currents of 50A to 100A can be handled by the internal diode between the input and output pins of the
device. In normal operations it is difficult to get those values of surge currents even with the use of large output
capacitances. If high value output capacitors are used, such as 1000µF to 5000µF and the input pin is instantaneously
shorted to ground, damage can occur. A diode from output to input is recommended, when a crowbar circuit at the input of
the AMS1084M is used. Normal power supply cycling or even plugging and unplugging in the system will not generate
current large enough to do any damage.
The adjustment pin can be driven on a transient basis ±25V, with respect to the output without any device degradation. As
with any IC regulator, none the protection circuitry will be functional and the internal transistors will break down if the
maximum input to output voltage differential is exceeded.
RIPPLE REJECTION
The ripple rejection values are measured with the adjustment pin bypassed. The impedance of the adjust pin capacitor at the
ripple frequency should be less than the value of R1 (normally 100Ω to 120Ω) for a proper bypassing and ripple rejection
approaching the values shown. The size of the required adjust pin capacitor is a function of the input ripple frequency. If
R1=100Ω at 120Hz the adjust pin capacitor should be 25µF. At 10kHz only 0.22µF is needed.
The ripple rejection will be a function of output voltage, in circuits without an adjust pin bypass capacitor. The output ripple
will increase directly as a ratio of the output voltage to the reference voltage (VOUT / VREF).
OUTPUT VOLTAGE
The AMS1084M series develops a 1.25V reference voltage between the output and
AMS1084M
the adjust terminal. 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.
This current is normally the specified minimum load current of 10mA. Because IADJ
is very small and constant it represents a small error and it can usually be ignored.
LOAD REGULATION
True remote load sensing it is not possible to provide, because the AMS1084M is a
three terminal device. The resistance of the wire connecting the regulator to the
load will limit the load regulation.
AMS1084M
The data sheet specification for load regulation is measured at the bottom of the
package. Negative side sensing is a true Kelvin connection, with the bottom of the
output divider returned to the negative side of the load.
The best load regulation is obtained when the top of the resistor divider R1 is
connected directly to the case not to the load. If R1 were connected to the load, the
effective resistance between the regulator and the load would be:
Connected as shown Fig.3, RΡ is not multiplied by the divider ratio. Using 16-gauge wire the parasitic line resistance is about
0.004Ω per foot, translating to 4mV/ft at 1A load current. It is important to keep the positive lead between regulator and load
as short as possible and use large wire or PC board traces.
BEIJING ESTEK ELECTRONICS CO.,LTD
Page 3 of 3
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