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PDF ADM2914 Data sheet ( Hoja de datos )
| Número de pieza | ADM2914 | |
| Descripción | Quad UV/OV Positive/Negative Voltage Supervisor | |
| Fabricantes | Analog Devices | |
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Data Sheet
FEATURES
Quad UV/OV positive/negative supervisor
Supervises up to 2 negative rails
Adjustable UV and OV input thresholds
High threshold accuracy over temperature: ±1.5%
1 V buffered reference output
Open-drain UV and OV reset outputs
Adjustable reset timeout with disable option
Outputs guaranteed down to VCC of 1 V
Glitch immunity
62 µA supply current
16-lead QSOP package
APPLICATIONS
Server supply monitoring
FPGA/DSP core and I/O voltage monitoring
Telecommunications equipment
Medical equipment
GENERAL DESCRIPTION
The ADM2914 is a quad voltage supervisory IC ideally suited
for monitoring multiple rails in a wide range of applications.
Each monitored rail has two dedicated input pins, VHx and VLx,
which allow each rail to be monitored for both overvoltage (OV)
and undervoltage (UV) conditions. A common active low
undervoltage (UV) and overvoltage (OV) pin is shared by each
of the monitored voltage rails.
The ADM2914 includes a 1 V buffered reference output, REF,
that acts as an offset when monitoring a negative voltage. The
three-state SEL pin determines the polarity of the third and
fourth inputs, that is, it configures the device to monitor
positive or negative supplies.
The device incorporates an internal shunt regulator that enables
the device to be used in higher voltage systems. This feature
Quad UV/OV Positive/Negative
Voltage Supervisor
ADM2914
FUNCTIONAL BLOCK DIAGRAM
VCC TIMER
ADM2914
VH1
500mV
TIMER
VL1
VH2
500mV
UV
VL2
VH3
OUTPUT
LOGIC
500mV
VL3
VH4
500mV
VL4
MUX
SEL GND
Figure 1.
OV
LOGIC
REF
LATCH/DIS
REF
requires a resistor to be placed between the main supply rail and
the VCC pin to limit the current flow into the VCC pin to no
greater than 10 mA. The ADM2914 uses the internal shunt
regulator to regulate VCC if the supply line exceeds the absolute
maximum ratings.
The ADM2914 is available in two models. The ADM2914-1
offers a latching overvoltage output that can be cleared by
toggling the LATCH input pin. The ADM2914-2 has a disable
pin that can override and disable both the OV and UV output
signals.
The ADM2914 is available in a 16-lead QSOP package. The
device operates over the extended temperature range of −40°C
to +125°C.
Rev. E
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityisassumedbyAnalogDevices for itsuse,nor foranyinfringementsofpatentsor other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2009–2015 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
1 page  
ADM2914
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
VCC
UV, OV
TIMER
VLx, VHx, LATCH, DIS, SEL
ICC
Reference Load Current (IREF)
IUV, IOV
Storage Temperature Range
Operating Temperature Range
Lead Temperature (Soldering, 10 sec)
Rating
−0.3 V to +6 V
−0.3 V to +16 V
−0.3 V to (VCC + 0.3 V)
−0.3 V to +7.5 V
10 mA
±1 mA
10 mA
−65°C to +150°C
−40°C to +125°C
300°C
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
Data Sheet
Table 3. Thermal Resistance
Package Type
16-Lead QSOP
ESD CAUTION
θJA
104
Unit
°C/W
Rev. E | Page 4 of 16
5 Page 
ADM2914
Data Sheet
THRESHOLD ACCURACY
The reset threshold accuracy is fundamental, especially at lower
voltage levels. Consider an FPGA application that requires a 1 V
core voltage input with tolerance of ±5%, where the supply has a
specified regulation, for example, ±1.5%. As shown in Figure 19, to
ensure that the supply is within the FPGA input voltage
requirement range, its voltage level must be monitored for UV
and OV conditions. The voltage swing on the supply itself
causes the voltage band available for setting the monitoring
threshold to be quite narrow. In this example, the threshold
voltages, including the tolerances, must fit within a monitor
region of only 0.035 V. The ADM2914 device with 0.1%
resistors can achieve this level of accuracy.
VOLTAGE
1.05V
1.015V
1V CORE
VOLTAGE
0.985V
0.95V
UV
+5% TOLERANCE
–5% TOLERANCE
3.5% RANGE FOR
OV MONITORING
+1.5% SUPPLY REGULATION
–1.5% SUPPLY
REGULATION
3.5% RANGE FOR
UV MONITORING
tUOTO
device, including all the tolerance factors, must fit within the
1.015 V to 1.05 V range. Similarly, the UV threshold range must
be between 0.95 V and 0.985 V.
The four worst-case scenarios of minimum and maximum
undervoltage and overvoltage thresholds are calculated as follows:
Minimum overvoltage threshold
VOV _ MIN
(0.5 V 1.5%)1 (RX
0.1%) (RY 0.1%)
RZ 0.1%
0.49251
(96,500 6420)(0.999)
(96,500)(1.001)
1.016 V 1.015 V
Maximum overvoltage threshold
VOV _ MAX
(0.5 V 1.5%)1 (RX
0.1%) (RY 0.1%)
RZ 0.1%
1.049 V 1.05 V
The maximum and minimum overvoltage threshold values lie
within the 1.015 V to 1.05 V range specified. The minimum and
maximum undervoltage thresholds are calculated as follows:
Minimum undervoltage threshold
TIME
Figure 19. Monitoring Threshold Accuracy Example
VOLTAGE MONITORING EXAMPLE
To illustrate how the ADM2914 device works in a real application,
consider the 1 V input example shown in Figure 19, with the
addition of a −12 V rail.
The first step is to choose the nominal current flow through
both voltage divider circuits, for example, 5 μA.
For the 1 V ±5% input, due to the specified ±1.5% regulation of
the supply, the UV and OV thresholds should be set in the middle
of the voltage monitoring band. In this case, on the ±3.25%
points of the supply, the UV threshold is 0.9675 V and the OV
threshold is 1.0325 V.
Input these values into Equation 1.
VUV _ MIN
(0.5 V 1.5%)1
(RX 0.1%)
RY 0.1% RZ 0.1%
0.953 V 0.95 V
Maximum undervoltage threshold
VUV _ MAX
(0.5 V 1.5%)1
RY
(R X
0.1%
0.1%)
RZ
0.1%
0.984 V 0.985 V
Again, these values fit within the specified undervoltage
monitoring range. All four worst-case scenarios satisfy the
tolerance requirement; therefore, the design approach is valid.
–12V RAIL
1V RAIL
5V
RZ
(0.5)1
1.0325 5106
96.5 kΩ
Insert the value of RZ into Equation 2.
RY
(0.5)1
0.9675 5106
96.5 kΩ 6.42 kΩ
Then substitute the calculated values for RZ and RY into
Equation 3.
RX
1
510 6
96.5 kΩ 6.42
kΩ
96.5
kΩ
96.5kΩ
6.42Ω
96.5kΩ 2.49MΩ
23.4kΩ
89.8kΩ
VH1
VCC
OV
VL1 UV
ADM2914
VL3
VH3
REF
GND
SEL
This design approach meets the application specifications. As
described previously, the 1 V rail is specified with an input
requirement of ±5% and a supply tolerance of ±1.5%. This
effectively means that the OV threshold of the monitoring
Rev. E | Page 10 of 16
Figure 20. Positive and Negative Supply Monitor Example
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet ADM2914.PDF ] | |
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