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| 型号： | ADM697ARZ-REEL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 5/12页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR MPU 16SOIC |
| 标准包装： | 1,000 |
| 类型： | 备用电池电路 |
| 监视电压数目： | 1 |
| 输出： | 推挽式，推挽式 |
| 复位： | 高有效/低有效 |
| 复位超时： | 最小为 35 ms |
| 电压 - 阀值： | 1.3V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 16-SOIC W |
| 包装： | 带卷 (TR) |
ADM696/ADM697
CIRCUIT INFORMATION
Battery-Switchover Section (ADM696)
The battery switchover circuit compares V CC to the V BATT
input, and connects V OUT to whichever is higher. Switchover
occurs when V CC is 50 mV higher than V BATT as V CC falls, and
when V CC is 70 mV greater than V BATT as V CC rises. This
20 mV of hysteresis prevents repeated rapid switching if V CC
falls very slowly or remains nearly equal to the battery voltage.
During normal operation with V CC higher than V BATT , V CC is
internally switched to V OUT via an internal PMOS transistor
switch. This switch has a typical on resistance of 1.5 ? and can
supply up to 100 mA at the V OUT terminal. V OUT is normally
used to drive a RAM memory bank which may require instanta-
neous currents of greater than 100 mA. If this is the case, then
a bypass capacitor should be connected to V OUT . The capacitor
will provide the peak current transients to the RAM. A capaci-
tance value of 0.1 μ F or greater may be used.
If the continuous output current requirement at V OUT exceeds
Low Line RESE T OUTPUT
RESET is an active low output which provides a RESET signal
to the microprocessor whenever the Low Line Input (LL IN ) is
below 1.3 V. The LL IN input is normally used to monitor the
power supply voltage. An internal timer holds RESET low for
50 ms after the voltage on LL IN rises above 1.3 V. This is in-
tended as a power-on RESET signal for the processor. It allows
time for the power supply and microprocessor to stabilize. On
power-down, the RESET output remains low with V CC as low
as 1 V. This ensures that the microprocessor is held in a stable
shutdown condition.
The LL IN comparator has approximately 12 mV of hysteresis
for enhanced noise immunity.
In addition to RESET , an active high RESET output is also
available. This is the complement of RESET and is useful for
processors requiring an active high RESET.
100 mA or if a lower V CC –V OUT voltage differential is desired,
an external PNP pass transistor may be connected in parallel
LL
IN
V2
V1
V2
V1
with the internal transistor. The BATT ON output can directly
drive the base of the external transistor.
RESET
t 1
t 1
A 20 ? MOSFET switch connects the V BATT input to V OUT
during battery backup. This MOSFET has very low input-to-
output differential (dropout voltage) at the low current levels
required for battery backup of CMOS RAM or other low power
CMOS circuitry. The supply current in battery backup is typi-
cally 0.6 μ A.
The ADM696 operates with battery voltages from 2.0 V to V CC
–0.3 V). High value capacitors, either standard electrolytic or
the farad-size double layer capacitors, can also be used for short-
term memory backup. A small charging current of typically
10 nA (0.1 μ A max) flows out of the V BATT terminal. This cur-
rent is useful for maintaining rechargeable batteries in a fully
charged condition. This extends the life of the backup battery
by compensating for its self discharge current. Also note that
this current poses no problem when lithium batteries are used
for backup since the maximum charging current (0.1 μ A) is safe
for even the smallest lithium cells.
If the battery-switchover section is not used, V BATT should be
connected to GND and V OUT should be connected to V CC .
V CC
V OUT
V BATT
GATE DRIVE
LOW LINE
t 1 = RESET TIME
V1 = RESET VOLTAGE THRESHOLD LOW
V2 = RESET VOLTAGE THRESHOLD HIGH
HYSTERESIS = V2–V1
Figure 2. Power-Fail Reset Timing
Watchdog Timer RESET
The watchdog timer circuit monitors the activity of the micro-
processor in order to check that it is not stalled in an indefinite
loop. An output line on the processor is used to toggle the
Watchdog Input (WDI) line. If this line is not toggled within
the selected timeout period, a RESET pulse is generated. The
ADM696/ADM697 may be configured for either a fixed
“short” 100 ms or a “long” 1.6 second timeout period or for an
adjustable timeout period. If the “short” period is selected some
systems may be unable to service the watchdog timer immedi-
ately after a reset, so a “long” timeout is automatically initiated
directly after a reset is issued. The watchdog timer is restarted
at the end of Reset, whether the Reset was caused by lack of ac-
tivity on WDI or by LL IN falling below the reset threshold.
The normal (short) timeout period becomes effective following
the first transition of WDI after RESET has gone inactive. The
700
mV
100
mV
INTERNAL
SHUT DOWN SIGNAL
WHEN
V BATT > (V CC + 0.7V)
BATT ON
(ADM691, ADM693,
ADM695, ADM696)
watchdog timeout period restarts with each transition on the
WDI pin. To ensure that the watchdog timer does not time out,
either a high-to-low or low-to high transition on the WDI pin
must occur at or less than the minimum timeout period. If WDI
remains permanently either high or low, reset pulses will be is-
sued after each timeout period (1.6 s). The watchdog monitor
can be deactivated by floating the Watchdog Input (WDI) or by
REV. 0
Figure 1. Battery Switchover Schematic
–5 –
connecting it to midsupply.
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相关代理商/技术参数 |
参数描述 |
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| adm697sq | 制造商:Analog Devices 功能描述: 制造商:Rochester Electronics LLC 功能描述:5V CMOS SUPERVISORS IC - Bulk |
| ADM698 | 制造商:AD 制造商全称:Analog Devices 功能描述:Microprocessor Supervisory Circuits |
| ADM698AN | 功能描述:IC SUPERVISOR MPU 4.65V 8DIP RoHS:否 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:400 系列:- 类型:备用电池电路 监视电压数目:1 输出:开路漏极，推挽式 复位:高有效/低有效 复位超时:最小为 35 ms 电压 - 阀值:4.65V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 供应商设备封装:16-SOIC W 包装:带卷 (TR) 其它名称:ADM691ARZ-REEL7TR |
| ADM698ANZ | 功能描述:IC SUPERVISOR MPU 4.65V 8DIP RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 其它有关文件:STM6717 View All Specifications 标准包装:1 系列:- 类型:多压监控器 监视电压数目:2 输出:开路漏极或开路集电极 复位:低有效 复位超时:最小为 600 ms 电压 - 阀值:1.11V，3.075V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:Digi-Reel® 产品目录页面:1194 (CN2011-ZH PDF) 其它名称:497-7019-6 |
| ADM698AQ | 制造商:AD 制造商全称:Analog Devices 功能描述:Microprocessor Supervisory Circuits |
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