ET-AMS1086M-XX [ESTEK]
1.5A LOW DROPOUT POSITIVE VOLTAGE; 1.5A低压差正电压
| 型号： | ET-AMS1086M-XX |
| 厂家： | 
Estek Electronics Co. Ltd |
| 描述： | 1.5A LOW DROPOUT POSITIVE VOLTAGE |
| 文件： | 总4页 (文件大小：567K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
September 2005
Inv № 426
ꢀ
ET- AMS1086M-XX
1.5A LOW DROPOUT POSITIVE VOLTAGE
REGULATOR
DESCRIPTION
The AMS1086M series of positive adjustable and fixed regulators are designed to provide 1.5A 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
PIN DESCRIPTION
•
•
•
High Efficiency Linear Regulators
Post Regulators for Switching Supplies
Adjustable Power Supply
FEATURES
•
•
•
•
•
•
•
Adjustable or Fixed Output
Output Current of 1.5A
Low Dropout, 1.5V max at 1.5A Output Current
0.04% Line Regulation
0.2 % Load Regulation
100% Thermal Limit Burn-In
Fast Transient Response
TYPICAL APPLICATION DATA
4.8V
4.95V
AMS1086M
AMS1086M-3.3
R2
R1
VOUT =VREF × 1+
+ IADJ × R2
BLOCK DIAGRAM
BEIJING ESTEK ELECTRONICS CO.,LTD
Page 1 of 4
ET- AMS1086M-XX
ABSOLUTE MAXIMUM RATINGS
SYMBOL
VCC
PARAMETER
VALUE
Internally Limited
15
UNIT
W
V
Power Dissipation
VIN
Input Voltage
Operation Junction Temperature Range
Control Section
Power Transistor
Storage Temperature Range
Lead Temperature (Soldering 10 sec)
TJ
0 to 125
0 to 150
-65 to +150
300
0C
TSTG
TLEAD
0C
0C
ELECTRICAL CHARACTERISTICS
ILOAD = 0mA and TJ = +25 0C (unless otherwise noted)
UNIT
PARAMETER
DEVICE
TEST CONDITIONS
MIN
TYP
MAX
VIN =5V, ILOAD = 10mA
1.238
1.225
1.250
1.250
1.262
1.275
Reference Voltage
Note 1
AMS1086M
V
VIN – VOUT = 1.5V to 10V,
*
ILOAD = 10mA to 1.5A
VIN – VOUT = 1.5V,
Variator from nominal VOUT
-1
-2
-
-
-
+1
+2
Output Voltage
Note 1
All fixed
versions
%
VIN – VOUT = 1.5V to 10V
ILOAD = 0mA to 1.5A,
*
*
Variator from nominal VOUT
ILOAD = 10mA,
VIN – VOUT = 1.5V to 10V
Line Regulation
Note 1
All
0.04
0.20
%
Load Regulation
Note 1
Minimum Load Current
VIN – VOUT = 1.5V
All
*
*
*
-
-
-
0.2
3
0.40
7
I
LOAD = 10mA to 1.5A
AMS1086M
VIN =5V, VADJ = 0V
VIN – VOUT = 1.5V
ILOAD = 10mA to 1.5A
VIN – VOUT = 1.5V to 10V
ILOAD = 10mA
mA
mA
All fixed
Ground Pin Current
7
10
versions
Adjust Pin Current
Current Limit
Ripple Rejection
Note 2
AMS1086M
*
*
*
-
40
2.2
65
90
-
µA
A
VIN – VOUT = 1.5V
VIN – VOUT = 3V
All
All
1.5
60
-
dB
I
LOAD = 1.5A
Dropout Voltage
Note 1,3
ILOAD = 1.5A
All
*
-
1.3
1.5
-
V
VIN – VOUT = 1.5V,
ILOAD = 10mA
Temperature Coefficient
All
*
-
0.005
%/0C
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%
BEIJING ESTEK ELECTRONICS CO.,LTD
Page 2 of 4
ET- AMS1086M-XX
APPLICATION INFORMATION
Internal resistors are limiting the internal current paths on
the AMS1086M adjustment pin, therefore even with
capacitors on the adjustment pin no protection diode is
needed to ensure device safety under short-circuit
conditions.
The AMS1086M 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.
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 AMS1086M is
used. Normal power supply cycling or even plugging and
unplugging in the system will not generate current large
enough to do any damage.
STABILITY
The circuit design used in the AMS1086M 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.
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.
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.
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 of
the input ripple frequency. If R1=100Ω at 120Hz the
adjust pin capacitor should be 25µF. At 10kHz only
0.22µF is needed.
PROTECTION DIODES
Unlike older regulators, the AMS1086M 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.
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
AMS1086M
voltage to the reference voltage (VOUT
/
VREF).
BEIJING ESTEK ELECTRONICS CO.,LTD
Page 3 of 4
ET- AMS1086M-XX
OUTPUT VOLTAGE
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:
The AMS1086M series develops a 1.25V reference
voltage between the output and 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.
AMS1086M
Connected as shown above, RP 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.
THERMAL CONSIDERATIONS
The AMS1086M series have internal power and thermal
limiting circuitry designed to protect the device under
overload conditions. However maximum junction
temperature ratings should not be exceeded under
continuous normal load conditions.
This current is normally the specified minimum load
current of 7mA. Because IADJ is very small and constant it
represents a small error and it can usually be ignored.
LOAD REGULATION
Careful consideration must be given to all sources of
thermal resistance from junction to ambient, including
junction-to-case, case-to-heat sink interface and heat sink
resistance itself. To ensure safe operating temperatures
and reflect more accurately the device temperature, new
thermal resistance specifications have been developed.
Unlike older regulators with a single junction-to-case
thermal resistance specification, the data section for
True remote load sensing it is not possible to provide,
because the AMS1086M is a three terminal device. The
resistance of the wire connecting the regulator to the load
will limit the load regulation.
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.
these new regulators provides
a separate thermal
resistance and maximum junction temperature for both
the Control Section and the Power Transistor.
Calculations for both temperatures under certain
conditions of ambient temperature and heat sink
resistance and to ensure that both thermal limits are met.
AMS1086M
Junction-to-case thermal resistance is specified from the
IC junction to the bottom of the case directly below the
die. This is the lowest resistance path for the heat flow. In
order to ensure the best possible thermal flow from this
area of the package to the heat sink proper mounting is
required. Thermal compound at the case-to-heat sink
interface is recommended. A thermally conductive spacer
can be used, if the case of the device must be electrically
isolated, but its added contribution to thermal resistance
has to be considered.
BEIJING ESTEK ELECTRONICS CO.,LTD
Page 4 of 4
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