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參數(shù)資料
| 型號： | MAX6728VFKAD4-T |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | TC7WB Series; Surface Mount Type: Y; Series Name: TC7WB; Function: Dual Low Voltage Bus Switch; Package: US8; Number Of Pins: 8 |
| 文件頁數(shù)： | 12/12頁 |
| 文件大?。?/td> | 206K |
| 代理商： | MAX6728VFKAD4-T |
Reset Input
The MAX6701(A)/MAX6702(A)/MAX6703(A) include two
adjustable reset inputs for monitoring up to a total of
three system voltages (including VCC). The thresholds
for the monitored RST_IN supplies are externally set
with resistor-divider networks (Figure 8). The reset out-
put is asserted if any of the monitored supplies (VCC,
RST_IN1, or RST_IN2) go below its specified threshold
and remains asserted for the reset timeout period after
all supplies are above their thresholds.
Applications Information
Ensuring a Valid RESET
Output Down to VCC = 0
When VCC falls below 1V, the MAX6701–MAX6708
RESET output no longer sinks current—it becomes an
open circuit. High-impedance CMOS logic inputs can
drift to undetermined voltages if left undriven. If a pull-
down resistor is added to the RESET pin as shown in
Figure 9, any stray charge or leakage currents are
drained to ground, holding RESET low. A resistor value
(R1) is not critical; 100k
is large enough not to load
RESET and small enough to pull RESET to ground. This
application works for push-pull output only (not for
open-drain resets).
Monitoring Other System Voltages
Other systems can be monitored by connecting a volt-
age-divider to PFI and adjusting the ratio appropriately.
In noisy systems, a capacitor between PFI and GND
reduces the power-fail circuit’s sensitivity to high-fre-
quency noise on the line being monitored. Reset can
be asserted on other voltages in addition to the VCC
supply line. Connect PFO to MR to initiate a reset out-
put pulse when PFI drops below 0.62V. Figure 10
shows the MAX6704–MAX6708 configured to assert a
reset output when the secondary supply falls below the
reset threshold.
Generating a Reset
from Watchdog Overflow
Connect WDO to MR to force a watchdog timeout to gen-
erate a reset pulse for only the reset timeout period on the
MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A). When the MAX6704 watch-
dog times out, reset outputs are automatically asserted
(no external connections required). For the MAX6701/
MAX6702/MAX6703/MAX6705/MAX6706/MAX6707 non-A
versions, do not connect WDO to MR; this creates a
locked condition.
MAX6701–08/MAX6701A–03A/05A–07A
Low-Voltage, SOT23 P Supervisors with Power-
Fail In/Out, Manual Reset, and Watchdog Timer
_______________________________________________________________________________________
9
tWD
+5V
0V
WDI
+5V
0V
WDO
+5V
0V
RESET
+5V
0V
(RESET)
tRP
+5V
0V
MR
( ) ARE FOR MAX6702(A)/MAX6706(A) ONLY.
tWDI
Figure 7. MAX6701(A)/MAX6702(A)/MAX6703(A)/MAX6705(A)/
MAX6706(A)/MAX6707(A) Watchdog Timing
R1
R2
0.62V
PFI, RST_IN1, OR RST_IN2
VEXTERNAL
0.62
R1 = R2 x
(
VEXT-TH
- 1
)
R2
VEXT-TH =
(1 + R1) x 0.62V
WHERE VEXT-TH IS THE EXTERNAL VOLTAGE TRIP LEVEL.
MAX6701(A)–
MAX6708
Figure 8. Calculating Adjustable Voltage Thresholds
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相關代理商/技術參數(shù) |
參數(shù)描述 |
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| MAX6729AKALTD3+ | 制造商:Maxim Integrated Products 功能描述:PROCESSOR SUPERVISOR 4.625V/3.075V 15UA 8PIN SOT-23 - Cut Tape Product |
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| MAX6729AKASDD3+ | 制造商:Maxim Integrated Products 功能描述:PROCESSOR SUPERVISOR 2.925V/0.788V 15UA 8PIN SOT-23 - Cut Tape Product |
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