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参数资料
| 型号： | MAX6750KA18-T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | µP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO8 |
| 封装： | SOT-23, 8 PIN |
| 文件页数： | 14/14页 |
| 文件大小： | 170K |
| 代理商： | MAX6750KA18-T |
Watchdog Timer
MAX6746–MAX6751
The watchdog’s circuit monitors the P’s activity. It the
P does not toggle the watchdog input (WDI) within
tWD (user-selected), RESET asserts for the reset time-
out period. The internal watchdog timer is cleared by
any event that asserts RESET, by a falling transition at
WDI (which can detect pulses as short as 300ns) or by
a transition at WDS. The watchdog timer remains
cleared while reset is asserted; as soon as reset is
released, the timer starts counting.
The MAX6746–MAX6751 feature two modes of watch-
dog operation: normal mode and extended mode. In nor-
mal mode (Figure 4a), the watchdog timeout period is
determined by the value of the capacitor connected
between SWT and ground. In extended mode (Figure
4b), the watchdog timeout period is multiplied by 128.
For example, in extended mode, a 0.1F capacitor gives
a watchdog timeout period of 65s (see the Extended-
Mode Watchdog Timeout Period vs. CSWT graph in the
Typical Operating Characteristics). To disable the watch-
dog timer function, connect SWT to ground.
MAX6752/MAX6753
The MAX6752 and MAX6753 have a windowed watch-
dog timer that asserts RESET for the adjusted reset
timeout period when the watchdog recognizes a fast
watchdog fault (tWDI < tWD1), or a slow watchdog fault
(period > tWD2). The reset timeout period is adjusted
independently of the watchdog timeout period.
The slow watchdog period, tWD2 is calculated as follows:
tWD2 = 0.65 x 109 x CSWT
with tWD2 in seconds and CSWT in Farads.
The fast watchdog period, tWD1, is selectable as a ratio
from the slow watchdog fault period (tWD2). Select the
fast watchdog period by pinstrapping SET0 and SET1,
where HIGH is VCC and LOW is GND. Table 1 illus-
trates the SET0 and SET1 configuration for the 8, 16,
and 64 window ratio ( tWD2/tWD1).
For example, if CSWT is 1500pF, and SET0 and SET1 are
low, then tWD2 is 975ms (typ) and tWD1 is 122ms (typ).
RESET asserts if the watchdog input has two falling
edges too close to each other (faster than tWD1) (Figure
5a) or falling edges that are too far apart (slower than
tWD2) (Figure 5b). Normal watchdog operation is dis-
played in (Figure 5c). The internal watchdog timer is
cleared when a WDI falling edge is detected within the
valid watchdog window or when RESET is deasserted.
All WDI inputs are ignored while RESET is asserted.
The watchdog timer begins to count after RESET is
deasserted. The watchdog timer clears and begins to
count after a valid WDI falling logic input. WDI falling
transitions within periods shorter than tWD1 or longer
than tWD2 force RESET to assert low for the reset time-
out period. WDI falling transitions within the tWD1 and
tWD2 window do not assert RESET. WDI transitions
between tWD1(min) and tWD1(max) or tWD2(min) and
tWD2(max) are not guaranteed to assert or deassert the
RESET. To guarantee that the window watchdog does
not assert the RESET, strobe WDI between tWD1(max)
and tWD2(min). The watchdog timer is cleared when
RESET is asserted or after a falling transition on WDI or
after a state change on SET0 or SET1. Disable the
watchdog timer by connecting SET0 high and SET1 low.
MAX6746–MAX6753
P Reset Circuits with Capacitor-Adjustable
Reset/Watchdog Timeout Delay
_______________________________________________________________________________________
9
tWD x 128
tRP
VCC
WDI
RESET
EXTENDED MODE (WDS = VCC)
VCC
OV
Figure 4b. Watchdog Timing Diagram, WDS = VCC
SET0
SET1
RATIO
LOW
8
LOW
HIGH
16
HIGH
LOW
Watchdog Disabled
HIGH
64
Table 1. Min/Max Watchdog Setting
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX6750KA19 | 制造商:Maxim Integrated Products 功能描述:SINGLE/DUAL-VOLT MICROPROC. RESET C - Rail/Tube |
| MAX6750KA19+T | 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 |
| MAX6750KA19-T | 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 |
| MAX6750KA20 | 制造商:Maxim Integrated Products 功能描述:SINGLE/DUAL-VOLT MICROPROC. RESET C - Rail/Tube |
| MAX6750KA20+T | 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 |
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