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PDF ASM805L Data sheet ( Hoja de datos )
| Número de pieza | ASM805L | |
| Descripción | (ASMxxxx) UP Power Supply Supervisor | |
| Fabricantes | Alliance Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ASM805L (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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October 2003
ASM690A / 692A
ASM802L / 802M
ASM805L
rev 1.0
µP Power Supply Supervisor With Battery Backup Switch
General Description
Applications
The AS690A / AS692A / AS802L / AS802M / AS805L offers
complete single chip solutions for power supply monitoring and
control battery functions in microprocessor systems. Each
device implements four functions: Reset control, watchdog
monitoring, battery-backup switching and power-failure
monitoring. In addition to microprocessor reset under power-up
and power-down conditions, these devices provide battery-
backup switching to maintain control in power loss and brown-
out situations. Additional monitoring capabilities can provide an
early warning of unregulated power supply loss before the
voltage regulator drops out. The important features of these
www.DafotuarSfuhnecetiot4nUs a.creo:m
• 1.6 second watchdog timer to keep microprocessor
responsive
• 4.40V or 4.65V VCC threshold for microprocessor reset at
power-up and power-down
• SPDT (Single-pole, Double-throw) PMOS switch connects
backup power to RAM if VCC fails
• 1.25V threshold detector for power loss or general purpose
voltage monitoring
These features are pin-compatible with the industry standard
power-supply supervisors. Short-circuit and thermal protection
have also been added. The AS690A / AS802L / AS805L
generate a reset pulse when the supply voltage drops below
4.65V and the AS692A / AS802M generate a reset below
4.40V. The ASM802L / ASM802M have power-fail accuracy to
± 2%. The ASM805L is the same as the ASM690A except that
RESET is provided instead of RESET.
Features
• Two precision supply-voltage monitor options
•4.65V (AS690A / AS802L / AS805L)
•4.40V (AS692A / AS802M )
• Battery-backup power switch on-chip
• Watchdog timer: 1.6 second timeout
• Power failure / low battery detection
• Short circuit protection and thermal limiting
• Small 8-pin SO package
• No external components
• Specified over full temperature range
• Embedded control systems
• Portable/Battery operated systems
• Intelligent instruments
• Wireless instruments
• Wireless communication systems
• PDAs and hand-held equipments
• µP / µC power supply monitoring
• Safety system
Typical Operating Circuit
Unregulated DC
Regulated +5V
R1 0.1 µF
VCC
RESET
PFI PFO
R2
VBATT
WDI
+_
3.6 V
Lithium
Battery
GND
VOUT
ASM690A
VCC
RESET
NMI
I/O LINE
GND
CMOS
VCC RAM
GND
Block Diagram
8
VBATT
Battery-Switchover Circuit
1
VOUT
2
VCC
6
WDI
4
PFI
+
|+ -
1.25V
3.5V
|+
+
-
Reset
Generator
Watchdog
Timer
|+
0.8V
-
+
1.25V
|+
-
+
ASM690A, ASM692A, ASM802L, ASM802M, (ASM805L)
7
RESET
(RESET)
5
PFO
3 GND
Alliance Semiconductor
2575 Augustine Drive . Santa Clara, CA 95054 . Tel: 408.855.4900 . Fax: 408.855.4999 . www.alsc.com
Notice: The information in this document is subject to change without notice
1 page  
October 2003
ASM690A / 692A
ASM802L / 802M
ASM805L
rev 1.0
Backup Power Sources - Batteries
Battery voltage selection is important to insure that the
battery does not discharge through the parasitic device diode
D1 (see Figure 3) when VCC is less than VBATT and VCC >
VRT.
Table 2: Maximum Battery Voltages
diode-resistor pair clamps the capacitor voltage at one diode
drop below VCC. VCC itself should be regulated within ±5% of
5V for the ASM692A/802M or within ±10% of 5V for the
ASM690A/802L/805L to insure that the storage capacitor
does not achieve an over voltage state.
Note: SuperCapTM is a trademark of Baknor Industries
Part Number MAXIMUM Battery Voltage
ASM690A
4.80
ASM802L
www.DataSAhSMee8t045UL.com
4.80
4.80
ASM692A
4.55
ASM802M
4.55
Although most batteries that meet the requirements of Table
2 are acceptable, lithium batteries are very effective backup
source due to their high-energy density and very low self-
discharge rates.
+5V
D1
+ 0.1F
VCC
VOUT
VBATT RESET
(RESET)
ASM692A
ASM802M
GND
To SRAM
To µP
Figure 4: Capacitor as a backup power source
Battery replacement while Powered
Batteries can be replaced even when the device is in a
powered state as long as VCC remains above the reset
threshold voltage VRT. In the ASM devices, a floating VBATT
pin will not cause a powersupply switchover as can occur in
some other supervisory circuits. If VBATT is not used, the pin
should be grounded.
Backup Power Sources - SuperCap™
Capacitor storage, with very high values of capacitance, can
be used as a back-up power source instead of batteries.
SuperCap™ are capacitors with capacities in the fractional
farad range. A 0.1 farad SuperCap™ would provide a useful
backup power source. Like the battery supply, it is important
that the capacitor voltage remain below the maximum
voltages shown in Table 2. Although the circuit of Figure 4
shows the most simple way to connect the SuperCap™, this
circuit cannot insure that an over voltage condition will not
occur since the capacitor will ultimately charge up to VCC. To
insure that an over voltage condition does not occur, the
circuit of Figure 5 is preferred. In this circuit configuration, the
+5V
D1
100K
VCC
VOUT
D2
VBATT RESET
+ 0.1F
(RESET)
ASM692A
ASM802M
GND
To SRAM
To µP
Figure 5: Capacitor as a backup power source
Voltage clamped to 0.5V below VCC
µP Power Supply Supervisor With Battery Backup Switch
5 of 13
Notice: The information in this document is subject to change without notice
5 Page 
October 2003
ASM690A / 692A
ASM802L / 802M
ASM805L
rev 1.0
Plastic DIP (8-Pin)
www.DataSheet4U.com
CerDIP (8-Pin)
SO (8-Pin)
Package Information
Inches
Millimeters
Min
Max
Min Max
Plastic DIP (8-Pin) *
A
-
0.210
- 5.33
A1 0.015
- 0.38 -
A2
0.115
0.195
2.92 4.95
b
0.014
0.022
0.36 0.56
b2
0.045
0.070
1.14 1.78
b3
0.030
0.045
0.80 1.14
D
0.355
0.400
0.80 1.14
D1 0.005
- 0.13 -
E
0.300
0.325
7.62 8.26
E1
0.240
0.280
6.10 7.11
e 0.100
-
2.54
eA 0.300
-
7.62
eB
-
0.430
- 10.92
eC - 0.060
L
0.115
0.150
2.92 3.81
CerDIP (8-Pin)
A
-
0.200
- 5.08
A1
0.015
0.070
0.38 1.78
b
0.014
0.023
0.36 0.58
B2
0.038
0.065
0.97 1.65
C
0.008
0.015
0.20 0.38
D
-
0.405
- 10.29
D1 0.005
- 0.13 -
E
0.290
0.320
7.37 8.13
E1
0.220
0.310
5.59 7.87
e 0.100
2.54
L
0.125
0.200
3.18 5.08
SO (8-Pin) **
A
0.053
0.069
1.35 1.75
A1
0.004
0.010
0.10 0.25
B
0.013
0.020
0.33 0.51
C
0.007
0.010
0.19 0.25
e 0.050
1.27
E
0.150
0.157
3.80 4.00
H
0.228
0.244
5.80 6.20
L
0.016
0.050
0.40 1.27
D
0.189
0.197
4.80 5.00
µP Power Supply Supervisor With Battery Backup Switch
11 of 13
Notice: The information in this document is subject to change without notice
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet ASM805L.PDF ] | |
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