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參數(shù)資料
| 型號： | 207463-1 |
| 英文描述： | BUCHSE SUB D CRIMPKONT GESTANZT 25POL |
| 中文描述： | 比克澤分?CRIMPKONT GESTANZT 25POL |
| 文件頁數(shù)： | 5/9頁 |
| 文件大?。?/td> | 137K |
| 代理商： | 207463-1 |
2
élanSC300 and élanSC310 Microcontrollers Solution For Systems Using A Back-Up Battery
Note:
This workaround requires the BIOS to read
Index Register 0DH as opposed to performing a check-
sum on the RTC RAM. Pulsing RESIN active will clear
VRT, but will not clear the RTC RAM contents.
Backup Battery
The Micro Power Off mode implementation on the
élanSC300 microcontroller allows the main system
power source to be turned off and a back-up power
source to be switched on to maintain power to the
AVCC and VCC pins. Keeping power applied to the
AVCC and VCC pins on the élanSC300 microcontroller
allows the integrated RTC to remain powered on in
Micro Power Off mode, preventing the loss of date,
time, and system configuration data.
If an RTC back-up battery is installed on a system with
power applied only to the AVCC and VCC pins, and the
main power source is unavailable or turned off, the
élanSC300 microcontroller will come up in an unde-
fined state. This causes power consumption in the mA
range, which could drain the secondary battery, de-
pending upon how long this condition is present.
When the élanSC300 microcontroller is powered up by
the main power source and has properly transitioned to
Micro Power Off mode, the undefined condition will not
be an issue as long as the back-up power source was
installed prior to the transition into Micro Power Off
mode. The undefined condition will occur only when
power is applied initially to the AVCC and VCC pins on
the élanSC300 microcontroller with the main power
source turned off or unavailable.
Suggested Workaround:
I
You should implement a switching circuit to allow a
clean transition from the main power source to the
back-up battery source when the system is put into
Micro Power Off mode. This circuit should also gate
off the back-up source from the VCC and AVCC
pins until a main power source is present the first
time. See Figure 1 for a circuit example. Table 1
shows the materials required for this particular cir-
cuit.
When designing this circuit, ensure that the voltage
at the anode of D1 and D3 is lower than that of the
VCC and AVCC pins; otherwise, the élanSC300 mi-
crocontroller will draw power from the back-up bat-
tery rather than the main power source. You should
also ensure that the voltage at the VCC Core and
AVCC pins does not drop out of DC specification
(3.0 V–3.6 V) during normal power-on because of
the forward drop of the Schottky diodes used.
I
If the system design guarantees that the back-up
battery will be in place before the main power
source is present, the following components may be
deleted from Figure 1: U1, R1, and C1. The
AC_GOOD input of U1 would then be tied directly to
U2, pin 3. This is because the CLK input of U2 must
only be clocked when VBATT is present. The
AC_GOOD signal can also be used to drive the
IORESET input to the élanSC300.
I
During the manufacturing process, install the back-
up battery when the system is powered by the main
power source prior to the transition into Micro
Power Off mode. This will prevent the élanSC300
microcontroller from coming up in the undefined
state.
Table 1.
Bill of Materials
Item
1
2
3
Quantity
1
1
1
Reference
U1
U2
Q1
Part
74HCT08
74HCT74
Siliconix SI9430DY
P-channel MOSFET
Rohm RB400D
Schottky diode
1-k
resistor
100-pF capacitor
390-K
resistor
2.2-μF capacitor
4
4
D1–D4
5
6
7
8
2
2
2
2
R1, R2
C1, C2
R3, R4
C3, C4
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 207463-1-P | 制造商:TE Connectivity / AMP 功能描述: |
| 207463-2 | 制造商:TE Connectivity 功能描述:Standard Cable Connectors |
| 207464-1 | 功能描述:D-Sub高密度連接器 HDP-20 25P PLUG RoHS:否 制造商:Amphenol Commercial Products 位置/觸點數(shù)量:9 排數(shù):2 安裝風(fēng)格:Wire 安裝角: 端接類型:Wirewrap 型式:Female |
| 207464-2 | 功能描述:D-Sub標(biāo)準(zhǔn)連接器 25P PLUG TIN IN RoHS:否 制造商:Omron Electronics 位置/觸點數(shù)量:9 排數(shù):2 型式:Female 安裝風(fēng)格:Through Hole 安裝角:Right 端接類型:Solder 過濾: |
| 207464-7 | 功能描述:D-Sub標(biāo)準(zhǔn)連接器 HDP-20 25P PLUG RoHS:否 制造商:Omron Electronics 位置/觸點數(shù)量:9 排數(shù):2 型式:Female 安裝風(fēng)格:Through Hole 安裝角:Right 端接類型:Solder 過濾: |
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