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PDF MAX6722A Data sheet ( Hoja de datos )
| Número de pieza | MAX6722A | |
| Descripción | SOT23 uP Supervisory Circuits | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-0536; Rev 1; 7/06
Dual/Triple, Ultra-Low-Voltage, SOT23 µP
Supervisory Circuits
General Description
The MAX6715A–MAX6729A are ultra-low-voltage micro-
processor (µP) supervisory circuits designed to monitor two
or three system power-supply voltages. These devices
assert a system reset if any monitored supply falls below its
factory-trimmed or adjustable threshold and maintain reset
for a minimum timeout period after all supplies rise above
their thresholds. The integrated dual/triple supervisory cir-
cuits significantly improve system reliability and reduce size
compared to separate ICs or discrete components.
www.DTahteasSehedeet4vUic.ceosmmonitor primary supply voltages (VCC1)
from 1.8V to 5.0V and secondary supply voltages (VCC2)
from 0.9V to 3.3V with factory-trimmed reset threshold
voltage options (see the Reset Voltage Threshold Suffix
Guide). An externally adjustable RSTIN input option
allows customers to monitor a third supply voltage down
to 0.62V. These devices are guaranteed to be in the cor-
rect reset output logic state when either VCC1 or VCC2
remains greater than 0.8V.
A variety of push-pull or open-drain reset outputs along
with watchdog input, manual reset input, and power-fail
input/output features are available (see the Selector
Guide). Select reset timeout periods from 1.1ms to
1120ms (min) (see the Reset Timeout Period Suffix
Guide). The MAX6715A–MAX6729A are available in small
5-, 6-, and 8-pin SOT23 packages and operate over the
-40°C to +125°C temperature range.
Applications
Multivoltage Systems
Telecom/Networking
Equipment
Computers/Servers
Portable/Battery-
Operated Equipment
Industrial Equipment
Printers/Fax Machines
Set-Top Boxes
Typical Operating Circuit
UNREGULATED
DC
R1
R2
IN
DC/DC OUT2
CONVERTER
OUT1
VCC1
VCC2
PUSHBUTTON
SWITCH
MAX6715A-
MAX6729A RST
RSTIN/PFI
WDI
MR PFO
MAX67_ _
1.8V 0.9V
I/O CORE
SUPPLY SUPPLY
RESET
I/O µP
NMI
Features
♦ VCC1 (Primary Supply) Reset Threshold Voltages
from 1.58V to 4.63V
♦ VCC2 (Secondary Supply) Reset Threshold
Voltages from 0.79V to 3.08V
♦ Externally Adjustable RSTIN Threshold for
Auxiliary/Triple-Voltage Monitoring
(0.62V Internal Reference)
♦ Watchdog Timer Option
35s (min) Long Startup Period
1.12s (min) Normal Timeout Period
♦ Manual Reset Input Option
♦ Power-Fail Input/Power-Fail Output Option
(Push-Pull and Open-Drain Active-Low)
♦ Guaranteed Reset Valid Down to VCC1 or
VCC2 = 0.8V
♦ Reset Output Logic Options
♦ Immune to Short VCC Transients
♦ Low Supply Current 14µA (typ) at 3.6V
♦ Watchdog Disable Feature
♦ Small 5-, 6-, and 8-Pin SOT23 Packages
Ordering Information
PART
TEMP
RANGE
MAX6715AUT_ _D_+T -40°C +125°C
MAX6716AUT_ _D_+T -40°C +125°C
MAX6717AUK_ _D_+T -40°C +125°C
MAX6718AUK_ _D_+T -40°C +125°C
MAX6719AUT_ _D_+T -40°C +125°C
MAX6720AUT_ _D_+T -40°C +125°C
+Denotes lead-free package.
PIN-
PACKAGE
6 SOT23-6
6 SOT23-6
5 SOT23-5
5 SOT23-5
6 SOT23-6
6 SOT23-6
PKG
CODE
U6-1
U6-1
U5-1
U5-1
U6-1
U6-1
Note: The first “_ _” are placeholders for the threshold voltage
levels of the devices. Desired threshold levels are set by the part
number suffix found in the Reset Voltage Threshold Suffix Guide.
The “_” after the D is a placeholder for the reset timeout delay
time. Desired delay time is set using the timeout period suffix
found in the Reset Timeout Period Suffix Guide. For example, the
MAX6716AUTLTD3-T is a dual-voltage supervisor VTH1 =
4.625V, VTH2 = 3.075V, and 210ms (typ) timeout period.
Ordering Information continued at end of data sheet.
Pin Configurations and Selector Guide appear at end of
data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
Dual/Triple, Ultra-Low-Voltage, SOT23 µP
Supervisory Circuits
(VCC1 = 5V, VCC2 = 3.3V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +5V, VCC2 = +3.3V)
20
TOTAL
18
16 ICC1
14
12
www.DataSheet4U.com
10
8
6
4 ICC2
2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +1.8V, VCC2 = +1.2V)
20
18
16
14
12
TOTAL
10
8 ICC1
6
4
2 ICC2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
NORMALIZED VCC RESET THRESHOLD
vs. TEMPERATURE
1.008
1.007
1.006
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +3.3V, VCC2 = +2.5V)
20
18
16
TOTAL
14
12
10 ICC1
8
6
4
ICC2
2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
NORMALIZED/RESET WATCHDOG
TIMEOUT PERIOD vs. TEMPERATURE
1.020
1.016
1.012
1.008
1.004
1.000
0.996
0.992
0.988
0.984
0.980
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
RESET INPUT AND POWER-FAIL INPUT
THRESHOLD vs. TEMPERATURE
638
637
636
635
634
633
632
631
630
629
628
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
(VCC1 = +2.5V, VCC2 = +1.8V)
20
18
16
14
TOTAL
12
10
ICC1
8
6
4
2 ICC2
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAXIMUM VCC TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
10,000
RESET OCCURS ABOVE
THIS LINE
1000
100
10
1
10 100 1000
RESET THRESHOLD OVERDRIVE (mV)
VCC TO RESET DELAY
vs. TEMPERATURE
20
75mV OVERDRIVE
19
18
17
16
15
14
13
12
11
10
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
_______________________________________________________________________________________ 5
5 Page 
Dual/Triple, Ultra-Low-Voltage, SOT23 µP
Supervisory Circuits
The normal watchdog timeout period (1.12s min)
begins after the first transition on WDI before the con-
clusion of the long initial watchdog period (Figure 2).
During the normal operating mode, the supervisor will
issue a reset pulse for the reset timeout period if the µP
does not update the WDI with a valid transition (high-to-
low or low-to-high) within the standard timeout period
(1.12s min).
Leave WDI unconnected to disable the watchdog timer.
The WDI floating-state detector uses a small (200nA typ)
current source. Therefore, do not connect WDI to any-
www.DthaitnagShtheaett4wUi.lcl soomurce more than 50nA.
Power-Fail Comparator
PFI is the noninverting input to a comparator. If PFI is
less than VPFI (626.5mV), PFO goes low. Common uses
for the power-fail comparator include monitoring prereg-
ulated input of the power supply (such as a battery) or
providing an early power-fail warning so software can
conduct an orderly system shutdown. It can also be
used to monitor supplies other than VCC1 or VCC2 by
setting the power-fail threshold with a resistor-divider, as
shown in Figure 3. PFI is the input to the power-fail com-
parator. The typical comparator delay is 2µs from PFI to
PFO. Connect PFI to ground of VCC1 if unused.
Ensuring a Valid Reset Output
Down to VCC = 0V
The MAX6715A–MAX6729A are guaranteed to operate
properly down to VCC = 0.8V. In applications that require
valid reset levels down to VCC = 0V, use a pulldown
resistor at RST to ground. The resistor value used is not
critical, but it must be large enough not to load the reset
output when VCC is above the reset threshold. For most
applications, 100kΩ is adequate. This configuration does
not work for the open-drain outputs of the MAX6715A/
MAX6717A/MAX6719A/MAX6721A/MAX6723A/MAX6725A/
MAX6727A/MAX6728A. For push-pull, active-high RST
output connect the external resistor as a pullup from RST
to VCC1.
A)
VIN
R1
MAX6728A/
MAX6729A
PFI PFO
R2
( )VTRIP = VPFI
R1 + R2
R2
GND
VTH
VCC tWDI-NORMAL
1.12s MAX
tWDI-STARTUP
35s MAX
WDI
1.12s MAX
RST tRP
B)
VCC
R1
MAX6728A/
MAX6729A
PFI PFO
R2
VIN
GND
[ ( ) ]VTRIP = R2
(VPFI)
1+
R1
1
R2
- VCC
R1
VPFI = 626.5mV
Figure 2. Normal Watchdog Startup Sequence
Figure 3. Using Power-Fail Input to Monitor an Additional
Power-Supply a) VIN is Positive b) VIN is Negative
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet MAX6722A.PDF ] | |
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