AVR180 - Atmel Corporation

AVR180: External Brown-out Protection
Features
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•
•
•
•
•
•
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Low-voltage Detector
Prevent Register and EEPROM Corruption
Two Discrete Solutions
Integrated IC Solution
Extreme Low-cost Solution
Extreme Low-power Solution
Formulas for Component Value Calculations
Complete with Example Schematics
8-bit
Microcontroller
Application
Note
Introduction
This application note shows in detail how to prevent system malfunction during periods of insufficient power supply voltage. It describes techniques to prevent the CPU
from executing code during periods of low power by use of external low voltage detectors. These events are often referred to as “Brown-outs”, where power supply voltage
drops to an insufficient level, or “Black-outs” where power supply voltage is completely
removed for a period of time.
Two discrete solutions are discussed in detail, allowing the user to calibrate the system requirements. A complete guide to Integrated Circuit (IC) solutions is also
included. By the use of these techniques, the following can be prevented in the situations described above:
•
CPU Register Corruption
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I/O Register Corruption
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I/O-pin Random Toggling
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SRAM Corruption
•
EEPROM Corruption
•
External Non-volatile Memory Corruption
Note that AVR® internal Flash Program Memory contents are never affected by insufficient power supply voltage.
Rev. 1051B–AVR–05/02
1
Theory of Operation
For the CPU to successfully decode and execute instructions, the supplied voltage must
always stay above the minimum voltage level set by the chosen operating frequency.
When supplied voltage drops below this level, the CPU may start to execute some
instructions incorrectly. The result is unexpected activity on the internal data and control
lines. This activity may cause CPU Registers, I/O Registers and Data Memories to get
corrupted.
To avoid these problems, the CPU should be prevented from executing code during
periods of insufficient supply voltage. This is best ensured by the use of an external
Power Supply Low Voltage Detector. Below a fixed threshold voltage VT, the detector
circuit forces the RESET pin low (active). Forcing RESET low immediately stops the
CPU from executing code. While the supplied voltage is below the required threshold
voltage VT, the MCU is halted, making sure the system stays in a known state. When
the supplied voltage rises above this predefined voltage, the RESET pin is again
released, and the MCU starts to execute code beginning at the Reset Vector (0x0000).
Threshold Voltage
It is recommended to set the threshold voltage 5 - 15% below typical VCC, to allow for
small fluctuations in supplied voltage. The threshold voltage should always be selected
to ensure that the detector will keep the device properly reset when supply voltage
drops below the critical voltage required by the CPU. Care should be taken to ensure
sufficiently high detector threshold voltage even in worst case situations.
Prevents CPU Register
Corruption
When the Detector keeps the MCU in Reset, all CPU activity is halted. When released
from Reset, the CPU Registers will all be in their default state. For the duration of the
Reset, the General Purpose Register File contents will be preserved.
Without a Detector, random CPU activity such as described in the introduction may
cause the CPU Registers to get corrupted. Also see “Volatile Memory” below.
Note:
Prevents I/O Register
Corruption
The General Purpose Register File contents are not guaranteed to be preserved during
Reset in the AT90S1200, the AT90S8515 and the AT90S4414.
When using a Detector to keep the MCU in reset, all I/O Registers will be kept in their
default state for the duration of the reset. Consequently, all On-chip peripherals will stay
in their reset state.
Without a Detector, random CPU activity such as described in the introduction may write
an unknown value to any I/O Register. This may cause unexpected behavior of the onchip peripherals.
Prevents I/O Pin Random A Detector will keep the MCU in Reset, and all I/O pins will be kept in their default state
for the duration of the Reset.
Toggling
Without a Detector, random CPU activity such as described in the introduction may write
a random value to the I/O Registers. This may cause random toggling of the I/O pins.
Prevents SRAM
Corruption
By the use of a Detector to keep the MCU in Reset, there will be no accesses to the
internal SRAM. The memory contents will keep their present contents for the duration of
the Reset.
Without a Detector, random CPU activity such as described in the introduction may write
an unknown value to any SRAM location. Also see “Volatile Memory” below.
Note:
2
The guaranteed preservation of data in internal SRAM does not apply to the AT90S8515
and 4414. In this device, the SRAM data is not guaranteed to be preserved during Reset.
AVR180
1051B–AVR–05/02
AVR180
Prevents Non-volatile
Memory Corruption
Non-volatile memories like EPROM, EEPROM, and Flash are designed to keep their
contents even when power is completely removed from the system. By the use of a
Detector to keep the MCU in Reset, all activity on the control lines cease. The memory
contents are such prevented from unintentional writes from the CPU for the duration of
the Reset.
Without a Detector, random CPU activity such as described in the introduction may initialize an unintended write to the non-volatile memory. This may cause random
corruption of the memory contents.
Notes:
1. As the AVR CPU is not capable of writing to its own program memory, the internal
Flash Program memory contents are never affected by a power failure situation.
2. For any write to non-volatile memory, a minimum voltage is required to successfully
write the new values into the memory. If supplied voltage at any time during the write
cycle drops below the minimum voltage, the write will fail, corrupting the location
written to.
3. In some AVR devices, when the reset activates during a write to the internal
EEPROM, the EEPROM Address Register will be set to zero (0x000). The result may
be seen as corruption of both the location being written, and of location zero (0x000).
Flash Program Memory
The Internal Flash Program Memory contents are never affected by a power failure situation. The AVR CPU is incapable of writing to its own program memory.
Volatile Memory
Even when external low voltage detectors halts the CPU, volatile memory (like Registers and RAM) will eventually loose their contents if the supply voltage drops below the
minimum voltage required for each memory cell to preserve its current value. When the
CPU is halted, the minimum voltage where the AVR internal RAM is guaranteed to preserve the contents is typically 2.0 volts. Factory tests on actual silicon have shown that
AVR devices may preserve the RAM contents even down to 0.5 - 1.0 volts.
Implementation
A variety of Integrated Circuit (IC) solutions are available from a range of manufacturers.
These offer a high accuracy solution at a low price, typically guaranteeing the threshold
voltage to be within ± 1%. Although the elementary three pin fixed voltage detector is
available, there is also a whole range of devices offering additional features like Reset
Pulse stretching, Power-on Reset Time-out, Watchdogs, Power regulation, dual supply
switching for UPS operation and more. Included in this application note is a guide to the
world of integrated circuit solutions. As an alternative, this application note also presents
two discrete Low-Power Supply Voltage RESET Detectors.
Design Hint: Supply
Voltage Filtering
•
Alternative 1: Minimum Power Consumption. Well-suited for battery-powered
applications where power consumption is the most critical parameter.
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Alternative 2: Minimum Cost. This is a minimum component cost solution for
applications where cost is a key parameter and power consumption is not critical.
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Alternative 3: High accuracy. High-quality semiconductor ICs are used to build an
accurate Brown-out Detector with low-power consumption.
Use low impedance capacitors (low ESR and ESL) on the VCC and multi-layer PCB with
power planes to improve transient rejection from the power supply.
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1051B–AVR–05/02
Alternative 1: Lowpower Consumption
Characteristics
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Very Low-power Consumption, (Typ 0.5µ[email protected], 1µ[email protected])
Low-cost
Large Hysteresis, Typ. 0.3 Volts
Fast Output Transitions
Accuracy ± 5-10%
High Component Count
Long Response Time on VCC
Figure 1. Low-power Consumption Brown-out Detector
VCC
R4
R1
R3
C3
R5
<50K
T3
T2
R2 C1
T1
C2
ISP
AVR
VCC
100 - 500K
OPTIONAL RESET
RESET
GND
SWITCH
Figure 2. These Oscilloscope Plots Show How the Voltage on RESET Varies with VCC
4
AVR180
1051B–AVR–05/02
AVR180
Introduction
The circuit in Figure 1 benefits from low-power consumption, which makes it suitable for
battery operated applications. Standard discrete components give a low cost design.
The voltage transition on the RESET pin is very steep. Combined with the large hysteresis, the accuracy is high. On the other hand, the response time is slow, which makes it
unsuitable for rapidly varying supply voltages.
Theory of Operation
This Detector has two stages, the Detector and the Amplifier. In the Detector stage, the
threshold voltage is set by the resistors R1 and R2 in relation to the critical voltage of
transistor T1. Under normal operation, this transistor is conducting, When the supply
voltage drops below the threshold voltage, the transistor shuts off.
The output from this Detector is lead to the input of the ultra low power Amplifier stage.
Under normal operation, the low voltage of the base of transistor T2 causes it to remain
shut, allowing resistor R5 to pull the RESET input high. The Amplifier stage also contains a hysteresis feedback loop through transistor T3, shorting resistor R3 in the
amplifier when the RESET output is kept low.
Choosing Components
T1, T2, and T3
The production spread of current gain β (or hFE) in transistors T1 affects the threshold
voltage VT (typically ± 0.2 volts). Most small signal transistors can be used, but low production spread transistors are recommended.
Care should be taken if transistor T1 is changed from one type to another. The emitterbase threshold voltage of T1 affects the constant (0.4) in the equation for threshold voltage (below). As a consequence, a change of transistor could cause a change in the
threshold voltage of the detector, which requires the voltage divider R1 + R2 to be
recalculated.
R1 and R2
R1 and R2 forms a voltage divider that defines the threshold voltage VT. As the threshold voltage depends on these resistors, it is recommended to choose resistors with 1%
tolerance or better. Also see “Noise Sensitivity” below.
R1 is usually chosen equal to 10 MΩ to ensure the lowest power consumption possible.
R2 is then found by the equation below. The constant (0.4) in the equation may vary
slightly with variations in transistor T1:
0,4
0,4 ⋅ R1
V T = ( R1 + R2 ) ⋅  -------- , or R2 = -------------------- R2 
V T – 0,4
R3
R3 is a non-critical pull-up resistor which has very little influence on the threshold voltage. It should be selected as large as possible to minimize power consumption. A
resistance of R3 greater than 10 MΩ is not recommended, see “Noise Sensitivity”
below.
R4
Resistor R4 defines the hysteresis of the threshold voltage (VT). By choosing R4 to 3.3
MΩ, the resulting hysteresis will be approximately 0.3 volts. A smaller R4 will give a
larger hysteresis, a larger R4 gives smaller hysteresis. A larger R4 will also result in a
less sharp transition in the output slope. Large deviations from the recommended value
will eventually alter the constant 0.4 in the threshold voltage equation above. As the hysteresis is only slightly changed with variation in R4 resistance, the accuracy is not
critical.
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1051B–AVR–05/02
R5
Resistor R5 pulls the RESET pin high in Normal Operating mode. A value less than
50 kΩ is recommended to tie RESET sufficiently hard to VCC. As no current passes
through this resistor in normal operating mode, its value and accuracy is otherwise of little importance. When RESET is pulled low, this resistor will start conducting a relatively
large current.
C1 and C2
Capacitors C1 and C2 short RF noise picked up in the circuitry and amplified by the
transistors. Both capacitors can be omitted, but a value greater than 1 nF is recommended. For maximum noise immunity, 100 nF (LF) or capacitors with lower ESR (HF)
should be selected when possible. Also see “Response Time” below. The accuracy is
not critical, but to ensure proper RF decoupling, the capacitors should have Z5U dielectric or better.
C3
Capacitor C3 decouples the power lines. It can be omitted if there is RF decoupling of
the power lines somewhere nearby on the circuit board, otherwise 1 nF is recommended. For maximum noise immunity, 100 nF (LF) or low ESR (HF) should be
selected.
Reset Switch/In-System
Programming
If a push button reset and/or ISP capabilities are required, they are simply connected in
parallel as shown in Figure 1. As the switch/programmer will pull RESET low, power
consumption in R5 will be relatively high for the duration of the event. Also see “Power
Consumption” below.
Response Time
Choosing large values for capacitors C1 and C2 will slow down the circuit’s response
time. This is not a problem with battery driven applications where the supply voltage
decreases slowly over time. Observe that the response time also applies to the time
immediately following Power-on. This might affect operation when a flat battery is
loaded. When power can drop more rapidly, the longer response time should be taken
into consideration.
Noise Sensitivity
Choosing values of R1 and R3 greater than 10 MΩ is not recommended, as it makes the
circuitry sensitive to thermal noise generated in the resistor. When noise is not critical,
the values of R1 and R3 can be raised to 20 MΩ. Choosing larger values will result in
the resistors not conducting sufficient current, giving in a non-functional Detector. If
more noise immunity is required, these resistors can be chosen smaller, at the expense
of increased power consumption.
Capacitors C1, C2 and C3 are decoupling capacitors to minimize noise sensitivity to
both RF and 50/60 Hz fields. They can all be omitted, but the noise immunity depend
strongly on the values selected.
Threshold Accuracy
6
As the threshold voltage is defined mainly by R1 and R2, inaccuracies in these resistors
directly influence the threshold voltage accuracy. It is recommended to choose these
with ± 1% tolerance.
AVR180
1051B–AVR–05/02
AVR180
Power Consumption
The current consumption in normal operating mode (sufficiently high VCC) is found by:
V CC
1
1
I ≈  ---------------------------------------------------------- = V CC  --------------------- + ---------------------
 ( R1 + R2 ) || ( R3 + R4 )
 R1 + R2 R3 + R4
When reset switch or programmer force RESET to GND, the current increases to:
V CC
I ≈ ------------------------------------------------------------------------------------------------||
( R1 + R2 ) ( R3 + R4 ) || R5 || R
RESET
When voltage drops to the level where the detector activates, transistor T1 closes, T2
opens and the current is:
V CC
I ≈ ----------------------------------------------------------------( R1 + R2 ) || R5 || R
RESET
As resistor R5 is usually chosen much smaller than the other resistors R1-R4, the last
two expressions both simplify to:
V CC
I ≈ --------------------------------||
R5 R
RESET
Table 1. Example Values
Example Values
Component
3.0V
4.5V
Recommended Tolerance
T1, T2
BC548/BC848/2N3904
ICE ≥ 2.5 mA, VCE ≥ 8 V, β/hFE ≥ 100
T3
BC558/BC858/2N3906
ICE ≥ 2.5 mA, VCE ≥ 8 V, β/hFE ≥ 100
R1
10 MΩ
≤ 1%
R2
1.54 MΩ
976 kΩ
≤ 1%
R3
10 MΩ
≤ 20%
R4
3.3 MΩ
≤ 20%
R5
47 kΩ
≤ 20%
C1, C2, C3
100 nF
≤ 20%, Z5U dielectric or better
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Alternative 2: Lowcost
Characteristics
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Low-component Count
Very Low-cost
Small Footprint
Short Response Time
Small Hysteresis
Output Drops Slowly with VCC
Low Accuracy (± 4-8%)
High Current Consumption
Sensitive to Component Variations
Figure 3. Low-cost Brown-out Detector
VCC
AVR
VCC
R2
T1
R1
R3
100 - 50K
RESET
GND
Figure 4. Low-cost Brown-out Detector with Manual Reset Button
VCC
ISP
R2
T1
R1
8
R3
R4
AVR
VCC
100 - 50K
OPTIONAL RESET
RESET
GND
SWITCH
AVR180
1051B–AVR–05/02
AVR180
Figure 5. These Oscilloscope Plots Show how the Voltage on RESET Varies with VCC
Introduction
Figure 3 is showing a circuit that features low cost and small physical size. However, its
high current consumption might make it unsuited for battery operated applications. As
the voltage transition on the RESET pin is fairly slow when VCC drops, the circuit is sensitive to inaccuracies in component values. Due to inaccuracies in resistors R1 and R2,
transistor T1 and AVR MCU RESET threshold value, the threshold value VT should be
chosen minimum 15% below nominal VCC.
Theory of Operation
During normal operation, the transistor T1 is open, keeping RESET at VCC. When the
supply voltage VCC drops below the threshold voltage (VT), the transistor T1 closes. This
allows resistor R3 to pull RESET low (active). The closing of the transistor T1 occurs
when the voltage from emitter to base drops below a certain value, usually 0.7 volts in
small signal silicon transistors.
R1 and R2 is a voltage divider that controls the emitter-base voltage. The threshold voltage, VT, is defined by:
R1 + R2
R1 V T
V T ≈ 0.7 ⋅ ---------------------, or ------- ≈ -------- – 1
R2
R2 0.7
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Choosing Components
T1
Almost any small signal PNP transistor can be used. One with high gain (β/hFE) is recommended as it gives faster transitions in the output voltage with variations in V CC
around the threshold voltage. Faster transitions make the circuit more immune to component variation, reducing the need to calibrate the Detector. Also see “Threshold
Accuracy” on page 6.
Calibration is also required if the threshold voltage for the transistor varies. This voltage
is the constant 0.7 in the equation above. The voltage is stable for the same type of transistor, but take care when selecting a transistor. A change in this parameter will
seriously affect the threshold voltage of the Detector.
R1 and R2
As the formula states, the threshold voltage VT is dependent upon R1 and R2. Resistor
R1 should be about 200 kΩ or lower. This ensures that the current out of the transistor
T1’s base will not influence the voltage divider R1-R2. (This is for an amplification
(β/hFE) value of at least 100.)
R3
The AVR’s RESET pin has an internal pull-up resistor with a nominal value of 100 500 kΩ. When transistor T1 is off, the internal pull-up and R3 form a voltage divider.
The resulting RESET voltage has to be sufficiently low to assure that the MCU RESET
line is held active. The recommended value for resistor R3 is 50 kΩ or lower, which
ensures that the voltage at RESET is always less than 1/3 VCC.
Reset Switch/In-System
Programming
If push button reset and/or ISP capabilities are required, a series resistor R4 must be
connected as shown in Figure 4. This resistor allows the reset switch/programmer to
override the transistor T1 and pull the RESET pin low. To ensure proper low voltage
detector operation, the series resistance in R3 + R4 should not exceed the recommended 50 kΩ.
Threshold Accuracy
As the threshold voltage is defined mainly by R1 and R2, inaccuracies in these resistors
directly influence the threshold voltage. It is recommended to use resistors with ± 1%
tolerance.
Due to the slow transitions on the output of the detector, variations in RESET threshold
in the AVR MCU will lead to inaccuracies in threshold voltage. This inaccuracy is typically ± 0.15 volts, which equals ± 3% in a 5V system. (± 5% at 3.3V). This inaccuracy is
lowered by choosing a transistor T1 with higher gain (β/hFE) which increases the transition speed.
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AVR180
1051B–AVR–05/02
AVR180
Power Consumption
The current through the detector in normal operating mode (sufficiently high VCC) is
found by:
V CC
1
1
I ≈ --------------------------------------- = V CC  --------------------- + -------
 R1 + R2 R3
( R1 + R2 ) || R3
When switch or programmer force RESET to GND, the current increases to:
V CC
I ≈ -----------------------------------------------------------------------------||
( R1 + R2 ) R3 || R4 || R
RESET
When voltage drops to the level where the transistor T1 closes, the current drops to:
V CC
I ≈ ------------------------------------------------------------------------------------( R1 + R2 ) || ( R3 + R4 + R
)
RESET
Table 2. Example Values
Example Values
Component
VT = 3.0V
VT = 4.5V
Recommended Tolerance
T1
BC558/BC858/2N3906
ICE ≥ 2.5 mA, VCE ≥ 8 V, β/hFE ≥ 100
R1
180 kΩ
≤ 1%
R2
56 kΩ
33 kΩ
≤ 1%
R3
≤ 47 kΩ
≤ 20%
R4
≤ 4.7 k
≤ 20%
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1051B–AVR–05/02
Alternative 3:
Integrated Circuit
Solutions
Characteristics
•
•
•
•
•
•
Introduction
A selection of integrated circuits is available from various semiconductor suppliers. They
vary from simple 3-pin fixed voltage detectors to advanced circuitry containing Watchdog Timers and Power-on Reset (POR) Timeouts. Because all AVR MCUs have built-in
Watchdog and POR circuitry, these functions do not require handling by the external IC.
The threshold accuracy is better than ± 1% for most circuits. Current consumption is in
the µA range. Make sure to choose a device with an active low output. A wide variety of
package types are available, ranging from miniature 3-pin SOT-23 to large packages
with high pin count.
Easy to Mount
Very Accurate Threshold Voltage
Low Power Consumption
Small Footprint
Low Component Count
Wide Variety in Additional Functionality
Figure 6. Detector with Push-pull Output
VCC
ISP
R1
1 - 4K
DETECTOR
LOGIC
RESET
OPTIONAL
RESET
SWITCH
Figure 7. Detector with Open-drain Output
VCC
ISP
RESET
DETECTOR
LOGIC
OPTIONAL
RESET
SWITCH
Figure 8. Alternative Location of Manual Reset Switch
VCC
VCC
RESET
GND
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AVR180
Output Driver
The IC Reset output can be push-pull or open drain (open collector), either CMOS or
TTL output levels. Open drain solutions allow easy connection of a manual reset button
and/or In-System Programmers. This feature can also be implemented with push-pull
outputs, with the addition of a resistor in series with the output. The ISP and/or manual
button is connected between the resistor and the AVR RESET input (see Figure 6 and
Figure 7).
Figure 9. Reset Pulse Stretching
VCC
VT
tBROWN-OUT
RESET WITHOUT
PULSE STRETCHING
RESET WITH
tBROWN-OUT tRST PULSE STRETCHING
Reset Pulse Stretching
An additional feature in some of these circuits is stretching of the reset pulse. The Reset
is held active for a defined amount of time after the condition (Power-on Reset, Brownout Reset etc.) that caused the reset has returned to normal (see Figure 9). Some of
these devices also provide this feature for the Manual Reset. The device senses the
output level, detecting the closing and opening of a reset button. When the button is
released, the device keeps the reset line active for an additional amount of time.
WARNING! This feature will interfere with the operation of an In-System Programmer,
which toggles the RESET line actively.
Power Regulator
Several integrated power regulators includes the Low-voltage Detector, combining both
functionalities in one device. This reduces part count, and often adds the functionality at
no extra cost.
Battery Backup
Solutions
Some systems contain a battery to supply power when the main power drops. The
power regulator in such systems often provides a status signal to the MCU telling which
source currently supplies power to the circuit. Connecting this signal to RESET will shut
the AVR down when battery power is used, preserving RAM contents but halting execution. Alternatively, connecting this signal to an input pin, the AVR can detect the event
and execute a safe power down sequence, switching off power hungry peripheral equipment (motor, display etc.) before entering Power-down mode. (The power consumption
in RESET is the same as in Normal Active Running mode, whereas the consumption in
power down mode is in the µA range.) When main power supply voltage returns to an
acceptable level, the AVR should detect the event, wake up and resume execution
where it left off.
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Figure 10. Adding Hysteresis to Threshold Voltage
VCC
R1
R2
DETECTOR
LOGIC
Hysteresis
ISP
R1
1 - 4K W RESET
OPTIONAL
RESET
SWITCH
Hysteresis in the Low-voltage Detector might be implemented in the integrated circuit, or
can be added with external circuitry (Figure 10). This prevents the detector from oscillating when used in battery applications.
Figure 11. Integrated Reset Circuit with Preset Threshold Voltage
VCC
AVR
VCC
ISP
VCC
RESET
GND
RESET
OPTIONAL
RESET
SWITCH
GND
Figure 12. Integrated Reset Circuit with Adjustable Threshold Voltage
VCC
VT
R1
VCC
ISP
RESET
IN RESET
R2
Fixed/Adjustable
Threshold Voltage
GND
AVR
VCC
OPTIONAL
RESET
SWITCH
GND
Some circuits offer the threshold voltage VT to be tuned by external components, while
others have a preset threshold voltage reference. The use of a fixed threshold voltage
IC is shown in Figure 11.
The typical connection for externally tuned threshold voltage is shown in Figure 12. This
device offers an internal voltage reference and a comparator. If the voltage at the input
pin is higher than the reference voltage, the output will be activated. The threshold voltage is easily defined by a voltage divider, R1 and R2.
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AVR180
Table 3. Example Devices
Device
MAX809(1)
MAX811
(1)
MAX821(1)
DS1811
(2)
DS1813/18
V6301
(2)
(3)
V6340(3)
Notes:
ISP Support
Cost Level(4)
Fixed Threshold Voltage, Fixed Pulse Stretching
Yes
A
Fixed Threshold Voltage, Fixed Pulse Stretching, Low Power, Manual Reset Input
Yes
A
Fixed Threshold Voltage, Adjustable Pulse Stretching, Low Power
Yes
Fixed Threshold Voltage, Fixed Pulse Stretching
Yes
Fixed Threshold Voltage, Fixed Pulse Stretching, Feedback Monitor
No
Fixed Threshold Voltage, Fixed Pulse Stretching, Low Power, Low Cost
Yes
C
Fixed Threshold Voltage, No Pulse Stretching, Low Cost
Yes
C
Features
1.
2.
3.
4.
Offered by Maxim Integrated Product, Inc.
Offered by Dallas Semiconductors.
Offered by EM Microelectronic-Marin SA.
A = expensive.
B = moderate.
C = inexpensive.
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TEL (44) 1355-803-000
FAX (44) 1355-242-743
e-mail
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Web Site
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© Atmel Corporation 2002.
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty
which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any errors
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not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted
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