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参数资料
| 型号： | MAX690RCSA-T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | 3.0V/3.3V Microprocessor Supervisory Circuits |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO8 |
| 封装： | 0.150 INCH, PLASTIC, SO-8 |
| 文件页数： | 12/12页 |
| 文件大小： | 281K |
| 代理商： | MAX690RCSA-T |
Connecting an ordinary signal diode in series with R3,
as shown in Figure 4b, causes the lower trip point (VL)
to coincide with the trip point without hysteresis (VTRIP),
so the entire hysteresis window occurs above VTRIP.
This method provides additional noise margin without
compromising the accuracy of the power-fail threshold
when the monitored voltage is falling. It is useful for
accurately detecting when a voltage falls past a
threshold.
The current through R1 and R2 should be at least 1A to
ensure that the 25nA (max over extended temperature
range) PFI input current does not shift the trip point. R3
should be larger than 10k
Ω so it does not load down the
–
P
—
F
—
O
–
pin. Capacitor C1 adds additional noise rejection.
Monitoring an Additional Power Supply
These P supervisors can monitor either positive or
negative supplies using a resistor voltage divider to
PFI.
–
P
—
F
—
O
–
can be used to generate an interrupt to the
P (Figure 5). Connecting
–
P
—
F
—
O
–
to
–
M
—
R
–
on the MAX704
and MAX806 causes reset to assert when the
monitored supply goes out of tolerance. Reset remains
asserted as long as
–
P
—
F
—
O
–
holds
–
M
—
R
–
low, and for 200ms
after
–
P
—
F
—
O
–
goes high.
Interfacing to Ps
with Bidirectional Reset Pins
Ps with bidirectional reset pins, such as the Motorola
68HC11 series, can contend with the MAX690_/
MAX704_/MAX802_/MAX806_
–
R
—
E
—
S
—
E
—
T
–
output. If, for
example, the
–
R
—
E
—
S
—
E
—
T
–
output is driven high and the P
wants to pull it low, indeterminate logic levels may
result. To correct this, connect a 4.7k
Ω resistor
between the
–
R
—
E
—
S
—
E
—
T
–
output and the P reset I/O, as in
Figure 6. Buffer the
–
R
—
E
—
S
—
E
—
T
–
output to other system
components.
Negative-Going VCC Transients
While issuing resets to the P during power-up, power-
down, and brownout conditions, these supervisors are
relatively immune to short-duration negative-going VCC
transients (glitches). It is usually undesirable to reset
the P when VCC experiences only small glitches.
Figure 7 shows maximum transient duration vs. reset-
comparator overdrive, for which reset pulses are not
generated. The graph was produced using negative-
going VCC pulses, starting at 3.3V and ending below
the reset threshold by the magnitude indicated (reset
comparator overdrive). The graph shows the maximum
pulse width a negative-going VCC transient may
typically have without causing a reset pulse to be
issued. As the amplitude of the transient increases
(i.e., goes farther below the reset threshold), the
maximum allowable pulse width decreases. Typically,
a VCC transient that goes 100mV below the reset
threshold and lasts for 40s or less will not cause a
reset pulse to be issued.
A 100nF bypass capacitor mounted close to the VCC
pin provides additional transient immunity.
MAX690T/S/R,
704T/S/R,
802T/S/R,
804–806T/S/R
3.0V/3.3V Microprocessor Supervisory Circuits
_______________________________________________________________________________________
9
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
VOUT
TO STATIC
RAM
VBATT
VCC
GND
1N4148
RESET
(RESET)
( ) ARE FOR MAX804T/S/R, MAX805T/S/R ONLY
TO
μP
0.47F
3.0V OR 3.3V
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
VOUT
TO STATIC
RAM
VBATT
VCC
GND
1N4148
RESET
(RESET)
( ) ARE FOR MAX804T/S/R, MAX805T/S/R ONLY
TO
μP
0.47F
3.0V OR
3.3V
+5V
b
a
Figure 3. Using a SuperCap as a Backup Power Source
相关PDF资料 |
PDF描述 |
|---|---|
| MAX690RESA-T | 3.0V/3.3V Microprocessor Supervisory Circuits |
| MAX690SCSA-T | 3.0V/3.3V Microprocessor Supervisory Circuits |
| MAX690SESA-T | 3.0V/3.3V Microprocessor Supervisory Circuits |
| MAX690TCSA-T | 3.0V/3.3V Microprocessor Supervisory Circuits |
| MAX690TESA-T | 3.0V/3.3V Microprocessor Supervisory Circuits |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX690REPA | 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX690REPA+ | 功能描述:监控电路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX690RESA | 功能描述:监控电路 RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX690RESA+ | 功能描述:监控电路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX690RESA+T | 功能描述:监控电路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
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