NSC LM3722E2.32MDC, LM3722EM5X-3.08, LM3722EM5-4.63, LM3722EM5-3.08, LM3722E4.63MWC Datasheet
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June 2001
LM3722/LM3723/LM3724
5-Pin Microprocessor Reset Circuits
General Description
The LM3722/LM3723/LM3724 microprocessor supervisory circuits monitor the power supplies in microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-down, brown-out conditions, and manual reset.
The LM3722/LM3723/LM3724 asserts a reset signal whenever the supply decreases below the factory-programmed reset threshold for at least 100 ms. The reset signal remains asserted for 190 ms after VCC rises above the threshold.
The LM3722 has an active-low RESET push-pull output. The LM3723 has an active-high RESET push-pull output. The LM3724 has an active-low open-drain RESET output.
Three standard reset voltage options are available, suitable for monitoring 5V, 3.3V, and 2.5V supply voltages. Additional reset voltages are also available; contact National Semiconductor for details.
With a low supply current of only 6µA, the LM3722/LM3723/LM3724 are ideal for use in portable equipment. The LM3722/LM3723/LM3724 are available in the 5-pin SOT23 package.
Features
nPrecise monitoring of 2.5V, 3.3V, and 5V supply voltages
nFully specified over temperature
Industrial: −40ÊC to +85ÊC
Extended: −40ÊC to +125ÊC
n100 ms minimum Power-On Reset pulse width, 190 ms typical:
Active-Low RESET Output (LM3722) Active-High RESET Output (LM3723) Active-Low RESET Open Drain Output (LM3724)
nGuaranteed RESET Output valid for VCC ³ 1V
nLow Supply Current, 6µA typical
nPower supply transient immunity
nCompatible with MAX811/812 applications
Applications
nMicroprocessor Systems
nComputers
nControllers
nIntelligent Instruments
nPortable/Battery-Powered Equipment
Typical Application Circuit
20014401 |
20014437 |
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Connection Diagram
SOT23-5
20014402
*( ) are for LM3723
Circuits Reset Microprocessor Pin-5 LM3722/LM3723/LM3724
© 2001 National Semiconductor Corporation |
DS200144 |
www.national.com |
LM3722/LM3723/LM3724
Ordering Information
Industrial Temperature Range (−40ÊC to +85ÊC):
Reset |
LM3722 Supplied as |
LM3722 Supplied as |
Package |
Package |
NSC Package |
Threshold (V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
Type |
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4.63 |
LM3722IM5-4.63 |
LM3722IM5X-4.63 |
R43B |
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3.08 |
LM3722IM5-3.08 |
LM3722IM5X-3.08 |
R41B |
SOT23-5 |
MF05A |
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2.32 |
LM3722IM5-2.32 |
LM3722IM5X-2.32 |
R34B |
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Reset |
LM3723 Supplied as |
LM3723 Supplied as |
Package |
Package |
NSC Package |
Threshold (V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
Type |
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4.63 |
LM3723IM5-4.63 |
LM3723IM5X-4.63 |
R13B |
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3.08 |
LM3723IM5-3.08 |
LM3723IM5X-3.08 |
R11B |
SOT23-5 |
MF05A |
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2.32 |
LM3723IM5-2.32 |
LM3723IM5X-2.32 |
R46B |
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Reset |
LM3724 Supplied as |
LM3724 Supplied as |
Package |
Package |
NSC Package |
Threshold (V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
Type |
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4.63 |
LM3724IM5-4.63 |
LM3724IM5X-4.63 |
R55B |
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3.08 |
LM3724IM5-3.08 |
LM3724IM5X-3.08 |
R53B |
SOT23-5 |
MF05A |
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2.32 |
LM3724IM5-2.32 |
LM3724IM5X-2.32 |
R50B |
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Extended Temperature Range (−40ÊC to +125ÊC):
Reset |
LM3722 Supplied as |
LM3722 Supplied as |
Package |
Package |
NSC Package |
Threshold (V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
Type |
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4.63 |
LM3722EM5-4.63 |
LM3722EM5X-4.63 |
R56B |
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3.08 |
LM3722EM5-3.08 |
LM3722EM5X-3.08 |
R57B |
SOT23-5 |
MF05A |
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2.32 |
LM3722EM5-2.32 |
LM3722EM5X-2.32 |
R58B |
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Reset |
LM3723 Supplied as |
LM3723 Supplied as |
Package |
Package |
NSC Package |
Threshold (V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
Type |
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4.63 |
LM3723EM5-4.63 |
LM3723EM5X-4.63 |
R59B |
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3.08 |
LM3723EM5-3.08 |
LM3723EM5X-3.08 |
R60 |
SOT23-5 |
MF05A |
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2.32 |
LM3723EM5-2.32 |
LM3723EM5X-2.32 |
R61B |
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Reset |
LM3724 Supplied as |
LM3724 Supplied as |
Package |
Package |
NSC Package |
Threshold (V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
Type |
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4.63 |
LM3724EM5-4.63 |
LM3724EM5X-4.63 |
R62B |
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3.08 |
LM3724EM5-3.08 |
LM3724EM5X-3.08 |
R63B |
SOT23-5 |
MF05A |
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2.32 |
LM3724EM5-2.32 |
LM3724EM5X-2.32 |
R64B |
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Custom voltages and improved accuracies are available, subject to minimum orders. Contact your local National Semiconductor Sales Office for information.
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Pin Description
PIN |
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NAME |
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FUNCTION |
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1 |
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GND |
Ground reference |
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GND |
Ground reference, device substrate, connect to ground. |
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Active-low output. |
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remains low while VCC is below the reset threshold |
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RESET |
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RESET |
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3 |
LM3722/LM3724 |
voltage, and for 190 ms after VCC rises above the reset threshold voltage. |
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RESET |
Active-high output. RESET remains high while VCC is below the reset threshold, and |
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LM3723 |
for 190 ms after VCC rises above the reset threshold. |
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Active-low input. Reset is asserted whenever this pin is pulled low and remains |
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4 |
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MR |
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asserted for 190 ms after the MR pin goes high. May be left open. |
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5 |
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VCC |
Supply Voltage (+5V, +3.3V, or +2.5V, nominal) |
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Block Diagram
LM3722/LM3723/LM3724 Block Diagram
20014435
LM3722/LM3723/LM3724
3 |
www.national.com |
LM3722/LM3723/LM3724
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
VCC, MR |
−0.3V to 6.0V |
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RESET, |
RESET |
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−0.3V to (V CC+ 0.3V) |
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Input Current, VCC Pin |
20mA |
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Output Current, RESET, |
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20mA |
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RESET |
Pin |
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ESD Rating (Note 2) |
2kV |
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Continuous Power Dissipation (TA = +70ÊC)
SOT-23 (Note 3) |
320mW |
Operating Temperature Range |
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Industrial: |
−40ÊC to +85ÊC |
Extended: |
−40ÊC to +125ÊC |
Maximum Junction Temperature |
125ÊC |
Storage Temperature Range |
−65ÊC to +160ÊC |
Lead Temperature |
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(soldering, 10sec) |
+300ÊC |
Electrical Characteristics
Typical values are at TA = +25ÊC. Limits with standard typeface are for TA = +25ÊC, and limits in boldface type apply for the operating temperature range (−40ÊC to +85ÊC) for LM372_IM5X, and (−40ÊC to +125ÊC) for LM372_EM5X, unless otherwise noted. (Note 4)
Symbol |
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Parameter |
Conditions |
Min |
Typ |
Max |
Units |
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VCC |
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VCC Range |
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1.0 |
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5.5 |
V |
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Supply Current |
LM372 _ -4.63 |
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VCC = 5.5V |
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8 |
15 |
µA |
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LM372 _ -3.08 |
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VCC = 3.6V |
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7 |
10 |
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(ILOAD = 0A) |
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LM372 _ -2.32 |
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VCC = 2.5V |
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6 |
10 |
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LM372 _ -4.63 |
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4.54 |
4.63 |
4.72 |
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4.50 |
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4.75 |
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VTH |
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Reset Threshold |
LM372 _ -3.08 |
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3.03 |
3.08 |
3.14 |
V |
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3.00 |
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3.15 |
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LM372 _ -2.32 |
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2.27 |
2.32 |
2.37 |
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2.25 |
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2.40 |
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VTH |
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Reset Threshold |
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30 |
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ppm/ÊC |
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Tempco |
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Temperature Coefficient |
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tRD |
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VCC to Reset Delay (Note 5) |
VCC = VTH to (VTH − 100mV) |
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20 |
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µs |
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tRP |
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Reset Active Timeout Period |
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100 |
190 |
560 |
ms |
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tMR |
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10 |
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µs |
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MR |
Minimum Pulse Width |
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tMD |
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MR |
to Reset Propagation |
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2 |
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µs |
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Delay |
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100 |
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ns |
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MR |
Glitch Immunity (Note 6) |
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VIH |
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VCC > VTH(MAX), LM372_ -4.63 |
2.3 |
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VIL |
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0.8 |
V |
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MR Input Threshold |
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VIH |
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VCC > VTH(MAX), LM372_ -3.08, LM372_ |
0.7 VCC |
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VIL |
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-2.32 |
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0.25 VCC |
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22 |
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kΩ |
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MR |
Pull-Up Resistance |
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VCC = VTH min, ISINK = 1.2mA, |
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0.3 |
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(LM3722-2.32/3.08) |
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RESET Output Voltage Low |
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VOL |
VCC = VTH min, ISINK = 3.2mA, |
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0.4 |
V |
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(LM3722) |
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(LM3722-4.63) |
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VCC > 1V, ISINK = 50µA |
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0.3 |
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VCC > VTH max, ISOURCE = 500µA, |
0.8VCC |
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(LM3722-2.32/3.08) |
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VOH |
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RESET |
Output Voltage High |
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V |
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(LM3722) |
VCC > VTH max, ISOURCE = 800µA, |
VCC−1.5 |
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(LM3722-4.63) |
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VCC = VTH max, ISINK = 1.2mA |
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0.3 |
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VOL |
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RESET Output Voltage Low |
(LM3723 -2.32/3.08) |
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V |
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(LM3723) |
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VCC = VTH max, ISINK = 3.2mA |
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0.4 |
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(LM3723 -4.63) |
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4 |
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