参数资料
型号: STM704SM6E
厂商: 意法半导体
英文描述: 3V Supervisor with Battery Switchover
中文描述: 3V的监控与电池切换
文件页数: 10/31页
文件大小: 194K
代理商: STM704SM6E
STM690/704/795/802/804/805/806
10/31
Chip-Enable Gating (STM795 only)
Internal gating of the chip enable (E) signal pre-
vents erroneous data from corrupting the external
CMOS RAM in the event of an undervoltage con-
dition. The STM795 uses a series transmission
gate from E to E
CON
(see Figure
12
). During nor-
mal operation (reset not asserted), the E transmis-
sion gate is enabled and passes all E transitions.
When reset is asserted, this path becomes dis-
abled, preventing erroneous data from corrupting
the CMOS RAM. The short E propagation delay
from E to E
CON
enables the STM795 to be used
with most μPs. If E is low when reset asserts,
E
CON
remains low for typically 10μs to permit the
current WRITE cycle to complete.
Chip Enable Input (STM795 only)
The chip-enable transmission gate is disabled and
E is high impedance (disabled mode) while reset
is asserted. During a power-down sequence when
V
CC
passes the reset threshold, the chip-enable
transmission gate disables and E immediately be-
comes high impedance if the voltage at E is high.
If E is low when reset asserts, the chip-enable
transmission gate will disable 10μs after reset as-
serts (see Figure
13
). This permits the current
WRITE cycle to complete during power-down.
Any time a reset is generated, the chip-enable
transmission gate remains disabled and E remains
high impedance (regardless of E activity) for the
first half of the reset time-out period (t
rec
/2). When
the chip enable transmission gate is enabled, the
impedance of E appears as a 40
resistor in se-
ries with the load at E
CON
. The propagation delay
through the chip-enable transmission gate de-
pends on V
CC
, the source impedance of the drive
connected to E, and the loading on E
CON
. The chip
enable propagation delay is production tested
from the 50% point on E to the 50% point on E
CON
using a 50
driver and a 50pF load capacitance
(see
Figure 35., page 22
). For minimum propaga-
tion delay, minimize the capacitive load at E
CON
and use a low-output impedance driver.
Chip Enable Output (STM795 only)
When the chip-enable transmission gate is en-
abled, the impedance of E
CON
is equivalent to a
40
resistor in series with the source driving E. In
the disabled mode, the transmission gate is off
and an active pull-up connects E
CON
to V
OUT
(see
Figure
12
). This pull-up turns off when the trans-
mission gate is enabled.
Figure 12. Chip-Enable Gating
Figure 13. Chip Enable Waveform (STM795)
AI08802
V
RST
V
OUT
V
CC
COMPARE
E
CON
t
Generator
E
CON
OUTPUT
CONTROL
RST
E
AI08855b
RST
E
V
CC
V
RST
V
BAT
E
CON
trec
trec
trec
trec
10μs
相关PDF资料
PDF描述
STM704SM6F 3V Supervisor with Battery Switchover
STM704TDS6E 3V Supervisor with Battery Switchover
STM704TDS6F 3V Supervisor with Battery Switchover
STM704TM6E 3V Supervisor with Battery Switchover
STM704TM6F 3V Supervisor with Battery Switchover
相关代理商/技术参数
参数描述
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STM704T 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:3V Supervisor with Battery Switchover
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