ADM8692ARN-REEL [ADI]

IC 2-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO8, MS-012AA, SOIC-8, Power Management Circuit;
ADM8692ARN-REEL
型号: ADM8692ARN-REEL
厂家: ADI    ADI
描述:

IC 2-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO8, MS-012AA, SOIC-8, Power Management Circuit

光电二极管
文件: 总20页 (文件大小:471K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
Microprocessor  
Supervisory Circuits  
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
FEATURES  
FUNCTIONAL BLOCK DIAGRAMS  
Upgrade for ADM690 to ADM695, MAX690 to MAX695  
Specified over temperature  
V
BATT  
V
Low power consumption (0.7 mW)  
Precision voltage monitor  
OUT  
V
CC  
Reset assertion down to 1 V VCC  
Low switch on resistance 0.7 Ω normal, 7 Ω in backup  
High current drive (100 mA)  
RESET  
GENERATOR  
1
RESET  
4.65V  
2
Watchdog timer: 100 ms, 1.6 s, or adjustable  
400 nA standby current  
Automatic battery backup power switching  
Extremely fast gating of chip enable signals (3 ns)  
Voltage monitor for power fail  
WATCHDOG  
TRANSITION DETECTOR  
(1.6s)  
ADM8690/  
ADM8692/  
ADM8694  
WATCHDOG  
INPUT (WDI)  
POWER FAIL  
INPUT (PFI)  
POWER FAIL  
OUTPUT (PFO)  
1.3V  
Available in TSSOP package  
1
2
VOLTAGE DETECTOR = 4.65V (ADM8690, ADM8694)  
4.40V (ADM8692)  
RESET PULSE WIDTH = 50ms (AD8690, ADM8692)  
200ms (ADM8694)  
APPLICATIONS  
Microprocessor systems  
Computers  
Figure 1. ADM8690/ADM8692/ADM8694  
Controllers  
Intelligent instruments  
Automotive systems  
BATT ON  
ADM8691/  
ADM8693/  
ADM8695  
V
BATT  
PRODUCT HIGHLIGHTS  
V
OUT  
The ADM8690, ADM8692, and ADM8694 are available in  
8-lead, PDIP packages and provide:  
V
CC  
CE  
IN  
CE  
OUT  
1. Power-on reset output during power-up, power-down, and  
LOW LINE  
RESET  
1
4.65V  
RESET  
brownout conditions. The  
output remains  
operational with VCC as low as 1 V.  
RESET AND  
RESET  
OSC IN  
2. Battery backup switching for CMOS RAM, CMOS  
microprocessor, or other low power logic.  
WATCHDOG  
GENERATOR  
TIME BASE  
RESET  
OSC SEL  
3. A reset pulse if the optional watchdog timer has not been  
toggled within a specified time.  
WATCHDOG  
INPUT (WDI)  
WATCHDOG  
TRANSITION DETECTOR  
WATCHDOG  
TIMER  
WATCHDOG  
OUTPUT (WDO)  
4. A 1.3 V threshold detector for power-fail warning, low battery  
detection, or to monitor a power supply other than 5 V.  
POWER FAIL  
INPUT (PFI)  
POWER FAIL  
OUTPUT (PFO)  
1.3V  
The ADM8691, ADM8693, and ADM8695 are available in 16-lead  
PDIP and small outline packages (including TSSOP) and  
provide three additional functions:  
1
VOLTAGE DETECTOR = 4.65V (ADM8691, ADM8695)  
4.40V (ADM8693)  
Figure 2. ADM8691/ADM8693/ADM8695  
1. Write protection of CMOS RAM or EEPROM.  
2. Adjustable reset and watchdog timeout periods.  
3. Separate watchdog timeout, backup battery switchover, and  
low VCC status outputs.  
Rev. A  
Information furnished by Analog Devices is believed to be accurate and reliable. However, no  
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other  
rights ofthird parties that may result fromits use. Specifications subject to change without notice. No  
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.  
Trademarks and registeredtrademarks arethe property of their respective owners.  
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.  
Tel: 781.329.4700  
Fax: 781.461.3113  
www.analog.com  
©2006 Analog Devices, Inc. All rights reserved.  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
TABLE OF CONTENTS  
Features .............................................................................................. 1  
Applications....................................................................................... 1  
Product Highlights ........................................................................... 1  
Functional Block Diagrams............................................................. 1  
Revision History ............................................................................... 2  
General Description......................................................................... 3  
Specifications..................................................................................... 4  
Absolute Maximum Ratings............................................................ 6  
ESD Caution.................................................................................. 6  
Pin Configurations and Function Descriptions ........................... 7  
Typical Performance Characteristics ............................................. 8  
Circuit Information........................................................................ 10  
Battery Switchover Section........................................................ 10  
Power-Fail Warning Comparator............................................. 13  
Application Information................................................................ 14  
Increasing the Drive Current.................................................... 14  
Using a Rechargeable Battery for Backup ............................... 14  
Adding Hysteresis to the Power-Fail Comparator................. 14  
Monitoring the Status of the Battery ....................................... 14  
Alternate Watchdog Input Drive Circuits............................... 15  
Typical Applications....................................................................... 16  
ADM8690, ADM8692, and ADM8694 ................................... 16  
ADM8691, ADM8693, and ADM8695 ................................... 16  
RESET  
Output ............................................................................ 16  
Power-Fail Detector ................................................................... 17  
RAM Write Protection............................................................... 17  
Watchdog Timer......................................................................... 17  
Outline Dimensions....................................................................... 18  
Ordering Guide .......................................................................... 19  
RESET  
Power-Fail  
Output......................................................... 10  
RESET  
Watchdog Timer  
Watchdog Output (  
............................................................ 11  
WDO  
) ........................................................ 12  
CE  
Gating and RAM Write Protection  
(ADM8691/ADM8693/ADM8695)......................................... 12  
REVISION HISTORY  
9/06—Rev. 0 to Rev. A  
Updated Format..................................................................Universal  
Changes to Absolute Maximum Ratings....................................... 6  
Updated Ordering Guide............................................................... 20  
2/97—Revision 0: Initial Version  
Rev. A | Page 2 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
GENERAL DESCRIPTION  
The ADM869x family of supervisory circuits offers complete  
single- chip solutions for power supply monitoring and battery  
control functions in microprocessor systems. These functions  
include microprocessor reset, backup battery switchover,  
watchdog timer, CMOS RAM write protection, and power  
failure warning. The complete family provides a variety of  
configurations to satisfy most microprocessor system  
requirements.  
extremely fast chip enable gating (3 ns), and high reliability.  
RESET  
addition, the power switching circuitry is designed for minimal  
voltage drop thereby permitting increased output current drive  
of up to 100 mA without the need of an external pass transistor.  
assertion is guaranteed with VCC as low as 1 V. In  
See Table 1 for a product selection guide listing the characteristics  
of each device in the ADM869x family. To place an order, use  
the Ordering Guide provided as the last section of this data sheet.  
The ADM869x family is fabricated using an advanced epitaxial  
CMOS process combining low power consumption (0.7 mW),  
Table 1. Product Selection Guide  
Part  
Number  
Nominal  
Reset Time  
Nominal VCC Reset  
Threshold  
Nominal Watchdog  
Timeout Period  
Battery Backup  
Switching  
Base Drive  
Ext PNP  
Chip Enable  
Signals  
ADM8690  
ADM8691  
ADM8692  
ADM8693  
ADM8694  
ADM8695  
50 ms  
50 ms or ADJ  
50 ms  
50 ms or ADJ  
200 ms  
200 ms or ADJ  
4.65 V  
4.65 V  
4.4 V  
4.4 V  
4.65 V  
4.65 V  
1.6 s  
100 ms, 1.6 s, ADJ  
1.6 s  
100 ms, 1.6 s, ADJ  
1.6 s  
100 ms, 1.6 s, ADJ  
Yes  
Yes  
Yes  
Yes  
Yes  
Yes  
No  
Yes  
No  
Yes  
No  
Yes  
No  
Yes  
No  
Yes  
No  
Yes  
Rev. A | Page 3 of 20  
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
SPECIFICATIONS  
VCC = full operating range, VBATT = 2.8 V, TA = TMIN to TMAX, unless otherwise noted.  
Table 2.  
Parameter  
Min  
Typ  
Max  
Unit  
Test Conditions/Comments  
BATTERY BACKUP SWITCHING  
VCC Operating Voltage Range  
ADM8690, ADM8691, ADM8694, ADM8695  
ADM8692, ADM8693  
4.75  
4.5  
5.5  
5.5  
V
V
VBATT Operating Voltage Range  
ADM8690, ADM8691, ADM8694, ADM8695  
ADM8692, ADM8693  
2.0  
2.0  
4.25  
4.0  
V
V
VOUT Output Voltage  
VCC − 0.005  
VCC − 0.2  
VCC − 0.0025  
VCC − 0.125  
V
V
IOUT = 1 mA  
IOUT ≤ 100 mA  
VOUT in Battery Backup Mode  
Supply Current (Excludes IOUT  
VBATT − 0.005 VBATT − 0.002  
V
μA  
μA  
IOUT = 250 μA, VCC < VBATT − 0.2 V  
IOUT = 100 μA  
VCC = 0 V, VBATT = 2.8 V  
5.5 V > VCC > VBATT + 0.2 V  
TA = 25°C  
)
140  
0.4  
200  
1
Supply Current in Battery Backup Mode  
Battery Standby Current  
+ = Discharge, − = Charge  
Battery Switchover Threshold  
VCC – VBATT  
Battery Switchover Hysteresis  
BATT ON Output Voltage  
BATT ON Output Short-Circuit Current  
−0.1  
+0.02 μA  
70  
50  
20  
mV  
mV  
mV  
V
mA  
μA  
Power-up  
Power-down  
0.3  
25  
ISINK = 3.2 mA  
BATT ON = VOUT = 4.5 V sink current  
BATT ON = 0 V source current  
55  
0.5  
2.5  
RESET AND WATCHDOG TIMER  
Reset Voltage Threshold  
ADM8690, ADM8691, ADM8694, ADM8695  
ADM8692, ADM8693  
Reset Threshold Hysteresis  
4.5  
4.25  
4.65  
4.4  
40  
4.73  
4.48  
V
V
mV  
Reset Timeout Delay  
ADM8690, ADM8691, ADM8692, ADM8693  
ADM8694, ADM8695  
Watchdog Timeout Period, Internal Oscillator  
35  
50  
200  
1.6  
100  
4064  
1011  
70  
ms  
ms  
s
OSC SEL = high  
OSC SEL = high  
Long period  
140  
1.0  
70  
3840  
768  
50  
280  
2.25  
140  
4097  
1025  
ms  
Short period  
Watchdog Timeout Period, External Clock  
cycles Long period  
cycles Short period  
ns  
mV  
V
Minimum WDI Input Pulse Width  
RESET Output Voltage @ VCC = 1 V  
RESET, LOW LINE Output Voltage  
VIL = 0.4, VIH = 3.5 V  
4
20  
I
I
SINK = 10 μA, VCC = 1 V  
0.05  
0.4  
SINK = 1.6 mA, VCC = 4.25 V  
3.5  
V
V
ISOURCE = 1 μA  
ISINK = 1.6 mA  
RESET, WDO Output Voltage  
0.4  
25  
3.5  
1
V
μA  
mA  
ISOURCE = 1 μA  
Output Short-Circuit Source Current  
Output Short-Circuit Sink Current  
WDI Input Threshold1  
Logic Low  
Logic High  
WDI Input Current  
10  
25  
0.8  
10  
V
V
μA  
μA  
3.5  
1
−1  
WDI = VOUT  
WDI = 0 V  
−10  
Rev. A | Page 4 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
Parameter  
Min  
Typ  
Max  
Unit  
Test Conditions/Comments  
POWER-FAIL DETECTOR  
PFI Input Threshold  
PFI Input Current  
PFO Output Voltage  
1.25  
−25  
1.3  
0.01  
1.35  
+25  
0.4  
V
nA  
V
VCC = 5 V  
I
SINK = 3.2 mA  
3.5  
1
V
ꢀA  
mA  
ISOURCE = 1 μA  
PFI = low, PFO = 0 V  
PFI = high, PFO = VOUT  
PFO Short-Circuit Source Current  
PFO Short-Circuit Sink Current  
3
25  
25  
CHIP ENABLE GATING  
CEIN Threshold  
0.8  
0.4  
7
V
VIL  
3.0  
V
μA  
V
VIH  
CEIN Pull-Up Current  
CEOUT Output Voltage  
3
3
I
SINK = 3.2 mA  
VOUT − 1.5  
VOUT − 0.05  
V
V
ns  
ISOURCE = 3.0 mA  
ISOURCE = 1 μA, VCC = 0 V  
CE Propagation Delay  
OSCILLATOR  
OSC IN Input Current  
2
5
μA  
μA  
kHz  
kHz  
OSC SEL Input Pull-Up Current  
OSC IN Frequency Range  
OSC IN Frequency with External Capacitor  
0
500  
OSC SEL = 0 V  
OSC SEL = 0 V, COSC = 47 pF  
4
1 WDI is a three-level input that is internally biased to 38% of VCC and has an input impedance of approximately 5 MΩ.  
Rev. A | Page 5 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
ABSOLUTE MAXIMUM RATINGS  
TA = 25°C, unless otherwise noted.  
Stresses above those listed under Absolute Maximum Ratings  
may cause permanent damage to the device. This is a stress  
rating only; functional operation of the device at these or any  
other conditions above those indicated in the operational  
section of this specification is not implied. Exposure to absolute  
maximum rating conditions for extended periods may affect  
device reliability.  
Table 3.  
Parameter  
Rating  
VCC  
VBATT  
All Other Inputs  
−0.3 V to +6 V  
−0.3 V to +6 V  
−0.3 V to VOUT + 0.5 V  
Input Current  
VCC  
VBATT  
ESD CAUTION  
200 mA  
50 mA  
GND  
20 mA  
Digital Output Current  
Power Dissipation, N-8 PDIP  
θJA Thermal Impedance  
Power Dissipation, R-8 SOIC  
θJA Thermal Impedance  
Power Dissipation, N-16 PDIP  
θJA Thermal Impedance  
Power Dissipation, RU-16 TSSOP  
θJA Thermal Impedance  
Power Dissipation, R-16 SOIC_N  
θJA Thermal Impedance  
Power Dissipation, RW-16 SOIC_W  
θJA Thermal Impedance  
Operating Temperature Range  
Industrial (A Version)  
Lead Temperature (Soldering, 10 sec)  
Storage Temperature Range  
20 mA  
400 mW  
120°C/W  
400 mW  
120°C/W  
600 mW  
135°C/W  
600 mW  
158°C/W  
600 mW  
110°C/W  
600 mW  
73°C/W  
−40°C to +85°C  
300°C  
−65°C to +150°C  
Rev. A | Page 6 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS  
V
1
2
3
4
5
6
7
8
16 RESET  
BATT  
V
RESET  
15  
OUT  
ADM8691/  
ADM8693/  
ADM8695  
V
WDO  
14  
CC  
V
V
1
2
3
4
8
7
6
5
OUT  
BATT  
ADM8690/  
ADM8692/  
ADM8694  
GND  
13 CE  
12 CE  
IN  
V
RESET  
WDI  
CC  
BATT ON  
LOW LINE  
OSC IN  
TOP VIEW  
OUT  
GND  
PFI  
(Not to Scale)  
TOP VIEW  
(Not to Scale)  
11 WDI  
10 PFO  
PFO  
OSC SEL  
9
PFI  
Figure 3. ADM8690, ADM8692, and ADM8694  
Pin Configuration  
Figure 4. ADM8691, ADM8693, and ADM8695  
Pin Configuration  
Table 4. Pin Function Descriptions  
Mnemonic Function  
VCC  
VBATT  
VOUT  
Power Supply Input. 5 V nominal.  
Backup Battery Input.  
Output Voltage. VCC or VBATT is internally switched to VOUT, depending on which is at the highest potential. VOUT can supply up to  
100 mA to power CMOS RAM. Connect VOUT to VCC if VOUT and VBATT are not used.  
GND  
Ground. This is the 0 V ground reference for all signals.  
RESET  
Logic Output. RESET goes low if VCC falls below the reset threshold, or the watchdog timer is not serviced within its timeout  
period. The reset threshold is typically 4.65 V for the ADM8690/ADM8691/ADM8694/ADM8695 and 4.4 V for the ADM8692  
and ADM8693. RESET remains low for 50 ms (ADM8690/ADM8691/ADM8692/ADM8693) or 200 ms (ADM8694/ADM8695)  
after VCC returns above the threshold. RESET also goes low for 50 ms (ADM8690/ADM8691/ADM8692/ADM8693) or 200 ms  
(ADM8694/ADM8695) if the watchdog timer is enabled but not serviced within its timeout period. The RESET pulse width can  
be adjusted on the ADM8691/ADM8693/ADM8695, as shown in Table 5. The RESET output has an internal 3 μA pull-up, and  
can either connect to an open collector reset bus or directly drive a CMOS gate without an external pull-up resistor.  
WDI  
Watchdog Input. WDI is a three-level input. If WDI remains either high or low for longer than the watchdog timeout period,  
RESET pulses low and WDO goes low. The timer resets with each transition on the WDI line. The watchdog timer can be  
disabled if WDI is left floating or is driven to midsupply.  
PFI  
Power-Fail Input. PFI is the noninverting input to the power-fail comparator. When PFI is less than 1.3 V, PFO goes low.  
Connect PFI to GND or VOUT when not used.  
PFO  
Power-Fail Output. PFO is the output of the power-fail comparator. It goes low when PFI is less than 1.3 V. The comparator is  
turned off and PFO goes low when VCC is below VBATT  
.
CEIN  
Logic Input. The input to the CE gating circuit. When not in use, connect this pin to GND or VOUT  
.
CEOUT  
Logic Output. CEOUT is a gated version of the CEIN signal. CEOUT tracks CEIN when VCC is above the reset threshold. If VCC is below  
the reset threshold, CEOUT is forced high. See Figure 21 and Figure 22.  
BATT ON  
Logic Output. BATT ON goes high when VOUT is internally switched to the VBATT input. It goes low when VOUT is internally  
switched to VCC. The output typically sinks 35 mA and can directly drive the base of an external PNP transistor to increase the  
output current above the 100 mA rating of VOUT  
.
LOW LINE  
Logic Output. LOW LINE goes low when VCC falls below the reset threshold. It returns high as soon as VCC rises above the reset  
threshold.  
RESET  
Logic Output. RESET is an active high output. It is the inverse of RESET.  
OSC SEL  
Logic Oscillator Select Input. When OSC SEL is unconnected (floating) or driven high, the internal oscillator sets the reset  
active time and watchdog timeout period. When OSC SEL is low, the external oscillator input, OSC IN, is enabled. OSC SEL has  
a 3 μA internal pull-up (see Table 5).  
OSC IN  
WDO  
Oscillator Logic Input. With OSC SEL low, OSC IN can be driven by an external clock signal or an external capacitor can be  
connected between OSC IN and GND. This sets both the reset active pulse timing and the watchdog timeout period (see  
Table 5 and Figure 17, Figure 18, Figure 19, and Figure 20). With OSC SEL high or floating, the internal oscillator is enabled and  
the reset active time is fixed at 50 ms typical (ADM8691/ADM8693) or 200 ms typical (ADM8695). In this mode, the OSC IN pin  
selects between fast (100 ms) and slow (1.6 s) watchdog timeout periods. In both modes, the timeout period immediately  
after a reset is 1.6 s typical.  
Logic Output. The watchdog output, WDO, goes low if WDI remains either high or low for longer than the watchdog timeout  
period. WDO is set high by the next transition at WDI. If WDI is unconnected or at midsupply, the watchdog timer is disabled  
and WDO remains high. WDO also goes high when LOW LINE goes low.  
Rev. A | Page 7 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
TYPICAL PERFORMANCE CHARACTERISTICS  
1.315  
1.310  
1.305  
1.300  
1.295  
1.290  
1.285  
1.280  
5.00  
4.99  
4.98  
4.97  
4.96  
4.95  
4.94  
–60  
–30  
0
30  
60  
90  
120  
10  
20  
30  
40  
50  
60  
70  
80  
90  
100  
TEMPERATURE (°C)  
I
(mA)  
OUT  
Figure 5. VOUT vs. IOUT Normal Operation  
Figure 8. PFI Input Threshold vs. Temperature  
2.800  
2.798  
2.796  
2.794  
2.792  
2.790  
2.788  
2.786  
53  
52  
51  
V
= 5V  
CC  
ADM8690/  
ADM8691/  
ADM8692/  
ADM8693  
50  
49  
20  
40  
60  
80  
100  
120  
150  
250  
350  
450  
550  
650  
750  
850  
950 1050  
TEMPERATURE (°C)  
I
(µA)  
OUT  
Figure 6. VOUT vs. IOUT Battery Backup  
Figure 9. Reset Active Time vs. Temperature  
4.69  
4.67  
V
= 5V  
CC  
A4  
3.36V  
100  
90  
4.65  
4.63  
4.61  
4.59  
4.57  
4.55  
10  
0%  
1V  
1V  
500ms  
–60  
–30  
0
30  
60  
90  
120  
TEMPERATURE (°C)  
Figure 7. Reset Output Voltage vs. Supply Voltage  
Figure 10. Reset Voltage Threshold vs. Temperature  
Rev. A | Page 8 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
6
5
4
3
2
1
0
6
V
T
= 5V  
PFI  
V
T
= 5V  
CC  
= 25°C  
CC  
= 25°C  
5
4
3
2
1
0
A
A
V
PFI  
5V  
PFO  
1.3V  
10k  
30pF  
V
PFI  
PFO  
PFI  
1.3V  
30pF  
PFO  
1.35  
1.25  
1.35  
1.25  
PFO  
0
0.2  
0.4  
0.6  
0.8  
TIME (µs)  
1.0  
1.2  
1.4  
1.6  
1.8  
0
0.1  
0.2  
0.3  
0.4  
TIME (µs)  
0.5  
0.6  
0.7  
0.8  
Figure 11. Power-Fail Comparator Response Time Falling  
Figure 13. Power-Fail Comparator Response Time with Pull-Up Resistor  
6
5
4
3
2
1
0
V
= 5V  
CC  
= 25°C  
T
A
V
PFI  
PFO  
1.3V  
30pF  
PFI  
1.35  
1.25  
PFO  
0
10  
20  
30  
40  
50  
60  
70  
80  
90  
TIME (µs)  
Figure 12. Power-Fail Comparator Response Time Rising  
Rev. A | Page 9 of 20  
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
CIRCUIT INFORMATION  
charged condition. This extends the life of the backup battery by  
BATTERY SWITCHOVER SECTION  
compensating for its self-discharge current. Also note that this  
current poses no problem when lithium batteries are used for  
backup because the maximum charging current (0.1 μA) is safe  
for even the smallest lithium cells.  
The battery switchover circuit compares VCC to the VBATT input,  
and connects VOUT to whichever is higher. Switchover occurs  
when VCC is 50 mV higher than VBATT as VCC falls, and when VCC  
is 70 mV greater than VBATT as VCC rises. This 20 mV of  
hysteresis prevents repeated rapid switching if VCC falls very  
slowly or remains nearly equal to the battery voltage.  
If the battery switchover section is not used, VBATT should be  
connected to GND and VOUT should be connected to VCC  
.
V
CC  
POWER-FAIL RESET OUTPUT  
V
OUT  
V
BATT  
RESET  
RESET  
is an active low output that provides a signal to  
the microprocessor whenever VCC is at an invalid level. When  
RESET  
output is forced  
GATE DRIVE  
V
CC falls below the reset threshold, the  
low. The nominal reset voltage threshold is 4.65 V (ADM8690/  
ADM8691/ADM8694/ADM8695) or 4.4 V (ADM8692/  
ADM8693).  
100  
mV  
BATT ON  
(ADM8690,  
ADM8695)  
INTERNAL  
SHUTDOWN SIGNAL  
WHEN  
700  
mV  
V
> (V + 0.7V)  
BATT  
CC  
V2  
V2  
V
V1  
V1  
CC  
Figure 14. Battery Switchover Schematic  
t1  
t1  
RESET  
During normal operation, with VCC higher than VBATT, VCC  
is internally switched to VOUT through an internal PMOS tran-  
sistor switch. This switch has a typical on resistance of 0.7 Ω  
and can supply up to 100 mA at the VOUT terminal. VOUT is  
normally used to drive a RAM memory bank, requiring  
instantaneous currents of greater than 100 mA. If this is the  
case, a bypass capacitor should be connected to VOUT. The  
capacitor provides the peak current transients to the RAM.  
A capacitance value of 0.1 μF or greater can be used.  
LOW LINE  
t
= RESET TIME  
1
V1 = RESET VOLTAGE THRESHOLD LOW  
V2 = RESET VOLTAGE THRESHOLD HIGH  
HYSTERESIS = V2–V1  
Figure 15. Power-Fail Reset Timing  
RESET  
On power-up,  
remains low for 50 ms (200 ms for  
If the continuous output current requirement at VOUT exceeds  
100 mA, or if a lower VCC − VOUT voltage differential is desired,  
an external PNP pass transistor can be connected in parallel  
with the internal transistor. The BATT ON output (ADM8691/  
ADM8693/ADM8695) can directly drive the base of the  
external transistor.  
ADM8694 and ADM8695) after VCC rises above the appropriate  
reset threshold. This allows time for the power supply and micro-  
RESET  
processor to stabilize. On power-down, the  
output remains  
low with VCC as low as 1 V. This ensures that the microprocessor  
is held in a stable shutdown condition.  
RESET  
This  
active time is adjustable on the ADM8691/ADM8693/  
A 7 Ω MOSFET switch connects the VBATT input to VOUT during  
battery backup. This MOSFET has very low input-to-output  
differential (dropout voltage) at the low current levels required  
for battery back up of CMOS RAM or other low power CMOS  
circuitry. The supply current in battery back up is typically 0.4 μA.  
ADM8695 by using an external oscillator or by connecting an  
external capacitor to the OSC IN pin. Refer to Table 5 and  
Figure 17, Figure 18, Figure 19, and Figure 20.  
The guaranteed minimum and maximum thresholds of the  
ADM8690/ADM8691/ADM8694/ADM8695 are 4.5 V and  
4.73 V, and the guaranteed thresholds of the ADM8692/ADM8693  
are 4.25 V and 4.48 V. The ADM8690/ADM8691/ADM8694/  
ADM8695 are, therefore, compatible with 5 V supplies with a  
+10%, −5% tolerance and the ADM8692/ADM8693 are com-  
patible with 5 V 10% supplies. The reset threshold comparator  
has approximately 50 mV of hysteresis. The response time of  
the reset voltage comparator is less than1 μs. If glitches are  
present on the VCC line that could cause spurious reset pulses,  
The ADM8690/ADM8691/ADM8694/ADM8695 operate with  
battery voltages from 2.0 V to 4.25 V, and the ADM8692/  
ADM8693 operate with battery voltages from 2.0 V to 4.0 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 μA maximum) flows out of the VBATT terminal. This current  
is useful for maintaining rechargeable batteries in a fully  
VCC should be decoupled close to the device.  
Rev. A | Page 10 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
RESET  
In addition to  
contain an active high RESET output. This is the complement of  
RESET  
, the ADM8691/ADM8693/ADM8695  
The normal (short) timeout period becomes effective following  
RESET  
the first transition of WDI after  
has gone inactive. The  
and is intended for processors requiring an active high  
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 are  
issued after each long (1.6 s) timeout period. The watchdog  
monitor can be deactivated by floating the watchdog input  
(WDI) or by connecting it to midsupply.  
reset signal.  
WATCHDOG TIMER RESET  
The watchdog timer circuit monitors the activity of the micro-  
processor 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  
RESET  
period, a  
pulse is generated. The nominal watchdog  
timeout period is preset at 1.6 seconds on the ADM8690/  
ADM8692/ADM8694. The ADM8691/ADM8693/ADM8695  
can 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 are unable to service  
the watchdog timer immediately after a reset, so the ADM8691/  
ADM8693/ADM8695 automatically select the long timeout  
period directly after a reset is issued. The watchdog timer is  
restarted at the end of reset, whether the reset was caused by  
lack of activity on WDI or by VCC falling below the reset  
threshold.  
WDI  
WDO  
t2  
t3  
RESET  
t1  
t1  
t1  
t1 = RESET TIME  
t2 = NORMAL (SHORT) WATCHDOG TIMEOUT PERIOD  
t3 = WATCHDOG TIMEOUT PERIOD IMMEDIATELY FOLLOWING A RESET  
Figure 16. Watchdog Timeout Period and Reset Active Time  
Table 5. ADM8691, ADM8693, ADM8695 Reset Pulse Width and Watchdog Timeout Selections  
Watchdog Timeout Period  
Reset Active Period  
OSC SEL  
OSC IN  
Normal  
Immediately After Reset  
ADM8691/ADM8693  
ADM8695  
2048 CLKs  
520 ms × C/47 pF  
200 ms  
Low1  
External clock input  
External capacitor  
Low  
1024 CLKs  
400 ms × C/47 pF  
100 ms  
4096 CLKs  
1.6 s × C/47 pF  
1.6 s  
512 CLKs  
200 ms × C/47 pF  
50 ms  
Low1  
Floating or high  
Floating or high  
Floating or high  
1.6 s  
1.6 s  
50 ms  
200 ms  
1 With the OSC SEL pin low, OSC IN can be driven by an external clock signal, or an external capacitor (C) can be connected between OSC IN and GND. The nominal  
internal oscillator frequency is 10.24 kHz. The nominal oscillator frequency with external capacitor is: FOSC (Hz) = 184,000/C (pF).  
Rev. A | Page 11 of 20  
 
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
8
7
On the ADM8690/ADM8692 the watchdog timeout period is  
OSC SEL  
NC  
fixed at 1.6 seconds and the reset pulse width is fixed at 50 ms.  
On the ADM8694 the watchdog timeout period is also 1.6 seconds  
but the reset pulse width is fixed at 200 ms. The ADM8691/  
ADM8693/ADM8695 allow these times to be adjusted, as shown  
in Table 5. Figure 17, Figure 18, Figure 19, and Figure 20 show  
ADM8691/  
ADM8693/  
ADM8695  
OSC IN  
Figure 20. Internal Oscillator (100 ms Watchdog)  
the various oscillator configurations that can be used to adjust  
the reset pulse width and watchdog timeout period.  
CE GATING AND RAM WRITE PROTECTION  
(ADM8691/ADM8693/ADM8695)  
The internal oscillator is enabled when OSC SEL is high or  
floating. In this mode, OSC IN selects between the 1.6 second  
and 100 ms watchdog timeout periods. With OSC IN connected  
high or floating, the 1.6 second timeout period is selected; and  
with it connected low, the 100 ms timeout period is selected. In  
either case, the timeout period is 1.6 seconds immediately after  
a reset. This gives the microprocessor time to reinitialize the  
system. If OSC IN is low, the 100 ms watchdog period becomes  
effective after the first transition of WDI. The software should  
be written such that the input/output port driving WDI is left in  
its power-up reset state until the initialization routines are  
completed and the microprocessor is able to toggle WDI at the  
minimum watchdog timeout period of 70 ms.  
The ADM8691/ADM8693/ADM8695 products include  
memory protection circuitry that ensures the integrity of data  
in memory by preventing write operations when VCC is at an  
CE  
CE  
invalid level. There are two additional pins ( IN and  
)
OUT  
that can be used to control the chip enable or write inputs of  
CE  
CMOS RAM. When VCC is present, OUT is a buffered replica  
CE  
of IN, with a 3 ns propagation delay. When VCC falls below the  
CE  
reset voltage threshold or VBATT, an internal gate forces  
CE  
OUT  
high, independent of  
.
IN  
CE  
CE CS  
, or write input of battery  
OUT typically drives the  
,
backed up CMOS RAM. This ensures the integrity of the data in  
memory by preventing write operations when VCC is at an  
invalid level. Similar protection of EEPROMs can be achieved  
WATCHDOG OUTPUT (WDO)  
CE  
using the OUT to drive the store or write inputs.  
WDO  
The Watchdog Output  
(ADM8691/ADM8693/ADM8695)  
provides a status output that goes low if the watchdog timer  
times out and remains low until set high by the next transition  
ADM8691  
ADM8693  
ADM8695  
WDO  
on the watchdog input.  
is also set high when VCC goes  
CE  
IN  
CE  
OUT  
below the reset threshold.  
V
V
LOW = 0  
OK = 1  
CC  
CC  
8
7
OSC SEL  
ADM8691/  
ADM8693/  
ADM8695  
Figure 21. Chip Enable Gating  
CLOCK  
0 TO 500kHz  
V2  
V2  
OSC IN  
V
V1  
V1  
CC  
Figure 17. External Clock Source  
t1  
t1  
RESET  
8
OSC SEL  
ADM8691/  
ADM8693/  
ADM8695  
LOW LINE  
7
OSC IN  
C
OSC  
Figure 18. External Capacitor  
CE  
IN  
8
OSC SEL  
NC  
NC  
ADM8691/  
ADM8693/  
ADM8695  
CE  
OUT  
7
OSC IN  
t
= RESET TIME  
1
V1 = RESET VOLTAGE THRESHOLD LOW  
V2 = RESET VOLTAGE THRESHOLD HIGH  
HYSTERESIS = V2–V1  
Figure 19. Internal Oscillator (1.6 Second Watchdog)  
Figure 22. Chip Enable Timing  
Rev. A | Page 12 of 20  
 
 
 
 
 
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
POWER-FAIL WARNING COMPARATOR  
Table 6. Input and Output Status in Battery Backup Mode  
An additional comparator is provided for early warning of  
failure in the microprocessor power supply. The power-fail  
input (PFI) is compared to an internal 1.3 V reference. The  
Signal  
Status  
VOUT  
VOUT is connected to VBATT via an internal PMOS  
switch.  
PFO  
power-fail output (  
) goes low when the voltage at PFI is less  
RESET  
RESET  
Logic low.  
than 1.3 V. Typically, PFI is driven by an external voltage divider  
that senses either the unregulated dc input to the system 5 V  
regulator or the regulated 5 V output. The voltage divider ratio  
can be chosen such that the voltage at PFI falls below 1.3 V  
several milliseconds before the 5 V power supply falls below the  
PFO  
Logic high. The open-circuit output voltage is equal  
to VOUT  
.
LOW LINE Logic low.  
BATT ON  
WDI  
Logic high. The open-circuit voltage is equal to VOUT  
.
WDI is ignored. It is internally disconnected from the  
internal pull-up resistor and does not source or sink  
current as long as its input voltage is between GND  
and VOUT. The input voltage does not affect supply  
current.  
reset threshold.  
is normally used to interrupt the  
microprocessor so that data can be stored in RAM and the shut-  
down procedure executed before power is lost.  
WDO  
PFI  
Logic high. The open circuit voltage is equal to VOUT.  
ADM869x  
INPUT  
POWER  
The power-fail comparator is turned off and has no  
effect on the power-fail output.  
Logic low.  
POWER  
FAIL  
OUTPUT  
1.3V  
PFO  
R1  
R2  
PFO  
CEIN  
POWER  
FAIL  
INPUT  
CEIN is ignored. It is internally disconnected from its  
internal pull-up and does not source or sink current  
as long as its input voltage is between GND and  
Figure 23. Power-Fail Comparator  
V
OUT. The input voltage does not affect supply  
current.  
CEOUT  
Logic high. The open circuit voltage is equal to VOUT  
OSC IN is ignored.  
OSC SEL is ignored.  
.
OSC IN  
OSC SEL  
Rev. A | Page 13 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
APPLICATION INFORMATION  
7V TO 15V  
INPUT  
POWER  
5V  
INCREASING THE DRIVE CURRENT  
7805  
If the continuous output current requirements at VOUT exceed  
100 mA, or if a lower VCC – VOUT voltage differential is desired,  
an external PNP pass transistor can be connected in parallel  
with the internal transistor. The BATT ON output (ADM8691/  
ADM8693/ADM8695) can directly drive the base of the  
external transistor.  
V
R
4
CC  
R
1
1.3V  
PFO  
TO  
PFI  
MICROPROCESSOR  
NMI  
ADM869x  
R
2
R
3
R
R
R
R
1
2
1
3
5V  
PNP TRANSISTOR  
1+  
= 1.3V  
+
V
H
(
)
5V INPUT  
POWER  
R
R (5V – 1.3V)  
(1.3V (R + R ))  
0.1µF  
0.1µF  
1
1
V
L
= 1.3V 1+  
(
)
PFO  
0V  
R
R
2
3
3
4
V
V
OUT  
BATT  
ON  
CC  
ASSUMING R < < R THEN  
4
3
R
V
1
BATT  
HYSTERESIS V – V = 5V (R )  
H
L
0V  
V
V
H
ADM8691/  
ADM8693/  
ADM8695  
L
2
BATTERY  
V
IN  
Figure 26. Adding Hysteresis to the Power-Fail Comparator  
MONITORING THE STATUS OF THE BATTERY  
Figure 24. Increasing the Drive Current  
The power-fail comparator can be used to monitor the status of  
the backup battery instead of the power supply, if desired. This  
is shown in Figure 27. The PFI input samples the battery voltage  
USING A RECHARGEABLE BATTERY FOR BACKUP  
If a capacitor or a rechargeable battery is used for backup then  
the charging resistor should be connected to VOUT because this  
eliminates the discharge path that would exist during power-  
PFO  
and generates an active low  
signal when the battery voltage  
drops below a chosen threshold. It can be necessary to apply a  
test load to determine the loaded battery voltage. This is done  
down if the resistor is connected to VCC  
.
V
– V  
R
CE  
CE  
under processor control using OUT. Because OUT is forced  
high during the battery backup mode, the test load is not  
applied to the battery while it is in use, even if the  
microprocessor is not powered.  
OUT  
BATT  
I =  
5V INPUT  
POWER  
0.1µF  
R
0.1µF  
V
V
OUT  
CC  
ADM869x  
5V INPUT  
POWER  
V
BATT  
RECHARGEABLE  
BATTERY  
V
V
BATT  
CC  
Figure 25. Rechargeable Battery  
PFO  
R
R
LOW BATTERY  
SIGNAL TO  
MICROPROCESSOR  
I/O PIN  
BATTERY  
10M  
10MΩ  
1
PFI  
ADM869x  
ADDING HYSTERESIS TO THE POWER-FAIL  
COMPARATOR  
2
20kΩ  
OPTIONAL  
CE  
IN  
FROM  
TEST LOAD  
For increased noise immunity, hysteresis can be added to the  
power-fail comparator. Because the comparator circuit is  
noninverting, hysteresis can be added simply by connecting a  
MICROPROCESSOR  
I/O PIN APPLIES  
TEST LOAD  
CE  
OUT  
TO BATTERY  
Figure 27. Monitoring the Battery Status  
PFO  
resistor between the  
output and the PFI input as shown in  
is low, Resistor R3 sinks current from the  
PFO  
Figure 26. When  
PFO  
summing junction at the PFI pin. When  
is high, the series  
combination of R3 and R4 sources current into the PFI  
summing junction. This results in differing trip levels for the  
comparator.  
Rev. A | Page 14 of 20  
 
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
This can be done under program control using the circuit  
shown in Figure 29. When the control input is high, the  
OSC SEL pin is low and the watchdog timeout is set by the  
external capacitor. A 0.01 μF capacitor sets a watchdog time-  
out delay of 100 seconds. When the control input is low, the  
OSC SEL pin is driven high, selecting the internal oscillator.  
The 100 ms or the 1.6 s period is chosen, depending on which  
diode is used, as shown in Figure 29. With D1 inserted, the  
internal timeout is set at 100 ms; with D2 inserted, the timeout  
is set at 1.6 seconds.  
ALTERNATE WATCHDOG INPUT DRIVE CIRCUITS  
The watchdog feature can be enabled and disabled under  
program control by driving WDI with a three-state buffer (see  
Figure 28). When three-stated, the WDI input floats, thereby  
disabling the watchdog timer.  
WATCHDOG  
WDI  
STROBE  
ADM869x  
CONTROL  
INPUT  
Figure 28. Programming the Watchdog Input  
CONTROL  
INPUT  
OSC SEL  
1
This circuit is not entirely foolproof, and it is possible for a  
software fault to erroneously three-state the buffer preventing  
the ADM869x from detecting that the microprocessor is no  
longer operating correctly. In most cases, a better method is to  
extend the watchdog period rather than disable the watchdog.  
D2  
ADM869x  
D1  
OSC IN  
1
LOW = INTERNAL TIMEOUT  
HIGH = EXTERNAL TIMEOUT  
Figure 29. Programming the Watchdog Input  
Rev. A | Page 15 of 20  
 
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
TYPICAL APPLICATIONS  
INPUT  
POWER  
V > 8V  
5V  
ADM8690, ADM8692, AND ADM8694  
7805  
0.1µF  
0.1µF  
R
1
Figure 30 shows the ADM8690/ADM8692/ADM8694 in a  
typical power monitoring, battery backup application. VOUT  
powers the CMOS RAM. Under normal operating conditions  
with VCC present, VOUT is internally connected to VCC. If a power  
failure occurs, VCC decays and VOUT is switched to VBATT, thereby  
V
POWER  
CC  
CMOS RAM  
POWER  
V
PFI  
OUT  
ADM8690/  
ADM8692/  
ADM8694  
R
2
MICROPROCESSOR  
SYSTEM  
RESET  
RESET  
V
BATT  
+
PFO  
WDI  
NMI  
RESET  
maintaining power for the CMOS RAM. A  
generated when VCC falls below 4.65 V for the ADM8690/  
RESET  
pulse is also  
BATTERY  
I/O LINE  
GND  
ADM8694 or 4.4 V for the ADM8692.  
remains low for  
Figure 31. ADM8690/ADM8692/ADM8694 Typical Application Circuit B  
50 ms (200 ms for the ADM8694) after VCC returns to 5 V.  
ADM8691, ADM8693, AND ADM8695  
The watchdog timer input (WDI) monitors an input/output line  
from the microprocessor system. This line must be toggled once  
every 1.6 seconds to verify correct software execution. Failure to  
toggle the line indicates that the microprocessor system is not  
correctly executing its program and can be tied up in an endless  
loop. If this happens, a reset pulse is generated to initialize the  
microprocessor.  
A typical connection for the ADM8691/ADM8693/ADM8695  
is shown in Figure 32. CMOS RAM is powered from VOUT  
When 5 V power is present, this is routed to VOUT. If VCC fails,  
BATT is routed to VOUT. VOUT can supply up to 100 mA from  
.
V
VCC, but if more current is required, an external PNP transistor  
can be added. When VCC is higher than VBATT, the BATT ON  
output goes low, providing up to 25 mA of base drive for the  
external transistor. A 0.1 μF capacitor is connected to VOUT to  
supply the transient currents for CMOS RAM. When VCC is  
lower than VBATT, an internal 20 Ω MOSFET connects the  
If the watchdog timer is not needed, the WDI input should be  
left floating.  
The power-fail input, PFI, monitors the input power supply via  
a resistive divider network. The voltage on the PFI input is  
compared with a precision 1.3 V internal reference. If the input  
backup battery to VOUT  
.
INPUT POWER  
5V  
PFO  
voltage drops below 1.3 V, a power-fail output (  
) signal is  
0.1µF  
0.1µF  
generated. This warns of an impending power failure and can  
be used to interrupt the processor so that the system can be shut  
down in an orderly fashion. The resistors in the sensing  
network are ratioed to give the desired power-fail threshold  
voltage (VT).  
V
BATT  
ON  
V
CC  
OUT  
CMOS  
RAM  
3V  
BATTERY  
CE  
V
OUT  
BATT  
ADM8691/  
ADM8693/  
ADM8695  
ADDRESS  
DECODE  
CE  
R
R
IN  
1
PFI  
A0 TO 15  
I/O LINE  
GND  
2
WDI  
PFO  
VT = (1.3 R1/R2) + 1.3 V  
NC  
OSC IN  
NMI  
OSC SEL  
RESET  
RESET  
0.1µF  
R1/R2 = (VT/1.3) − 1  
MICROPROCESSOR  
SYSTEM  
LOW LINE WDO  
RESET  
5V  
R
R
SYSTEM STATUS  
INDICATORS  
1
2
POWER  
V
CC  
CMOS RAM  
POWER  
V
PFI  
OUT  
Figure 32. ADM8691/ADM8693/ADM8695 Typical Application  
0.1µF  
ADM8690/  
ADM8692/  
ADM8694  
MICROPROCESSOR  
SYSTEM  
RESET OUTPUT  
RESET  
The internal voltage detector monitors VCC and generates a  
RESET  
V
BATT  
+
PFO  
WDI  
NMI  
RESET  
output to hold the microprocessor reset line low when  
CC is below 4.65 V (4.4 V for ADM8693). An internal timer  
BATTERY  
I/O LINE  
GND  
V
RESET  
holds  
low for 50 ms (200 ms for the ADM8695) after  
Figure 30. ADM8690/ADM8692/ADM8694 Typical Application Circuit A  
VCC rises above 4.65 V (4.4 V for the ADM8693). This prevents  
RESET  
repeated toggling of  
, even if the 5 V power drops out  
Figure 31 shows a similar application, but in this case the PFI  
input monitors the unregulated input to the 7805 voltage  
regulator. This gives an earlier warning of an impending power  
failure. It is useful with processors operating at low speeds or  
where there are a significant number of housekeeping tasks to  
be completed before the power is lost.  
and recovers with each power line cycle.  
The crystal oscillator normally used to generate the clock for  
microprocessors can take several milliseconds to stabilize.  
Because most microprocessors need several clock cycles to  
RESET  
reset,  
must be held low until the microprocessor clock  
RESET  
oscillator has started. The power-up  
pulse lasts 50 ms  
Rev. A | Page 16 of 20  
 
 
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
(200 ms for the ADM8695) to allow for this oscillator start-up  
microprocessor from writing erroneous data into RAM during  
power-up, power-down, brownouts, and momentary power  
interruptions.  
time. If a different reset pulse width is required, a capacitor  
should be connected to OSC IN, or an external clock can be  
used. Refer to Table 5 and Figure 17, Figure 18, Figure 19, and  
Figure 20. The manual reset switch and the 0.1 μF capacitor  
connected to the reset line can be omitted if a manual reset is  
not needed. An inverted, active high, RESET output is also  
available.  
WATCHDOG TIMER  
The microprocessor drives the watchdog input (WDI) with an  
input/output line. When OSC IN and OSC SEL are unconnected,  
the microprocessor must toggle the WDI pin once every  
1.6 seconds to verify proper software execution. If a hardware  
or software failure occurs such that WDI is not toggled, the  
ADM8691/ADM8693 issues a 50 ms (200 ms for the ADM8695)  
POWER-FAIL DETECTOR  
The 5 V VCC power line is monitored via a resistive potential  
divider connected to the power-fail input (PFI). When the  
RESET  
pulse after 1.6 seconds. This typically restarts the micro-  
PFO  
voltage at PFI falls below 1.3 V, the power-fail output (  
)
RESET  
processor power-up routine. A new  
pulse is issued every  
drives the processors NMI input low. If, for example, a power-  
fail threshold of 4.8 V is set with Resistor R1 and Resistor R2, the  
microprocessor has the time when VCC falls from 4.8 V to 4.65 V  
to save data into RAM. An earlier power-fail warning can be  
generated if the unregulated dc input to the 5 V regulator is  
available for monitoring. This allows more time for microprocessor  
housekeeping tasks to be completed before power is lost.  
1.6 seconds until WDI is again strobed. If a different watchdog  
timeout period is required, a capacitor should be connected to  
OSC IN or an external clock can be used. Refer to Table 5 and  
Figure 17, Figure 18, Figure 19, and Figure 20.  
WDO  
The watchdog output (  
not serviced within its timeout period. Once  
) goes low if the watchdog timer is  
WDO  
goes low, it  
remains low until a transition occurs at WDI. The watchdog  
timer feature can be disabled by leaving WDI unconnected.  
RAM WRITE PROTECTION  
CE  
The ADM8691/ADM8693/ADM8695 OUT line drives the  
RESET  
The  
output has an internal 3 μA pull-up and can either  
CE  
CE  
chip select inputs of the CMOS RAM. OUT follows IN as  
long as VCC is above the 4.65 V (4.4 V for the ADM8693) reset  
threshold.  
connect to an open collector reset bus or directly drive a CMOS  
gate without an external pull-up resistor.  
CE  
If VCC falls below the reset threshold, OUT goes high,  
CE  
independent of the logic level at IN. This prevents the  
Rev. A | Page 17 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
OUTLINE DIMENSIONS  
0.400 (10.16)  
0.365 (9.27)  
5.00 (0.1968)  
4.80 (0.1890)  
0.355 (9.02)  
8
1
5
4
8
5
4
0.280 (7.11)  
0.250 (6.35)  
0.240 (6.10)  
6.20 (0.2440)  
5.80 (0.2284)  
4.00 (0.1574)  
3.80 (0.1497)  
1
0.325 (8.26)  
0.310 (7.87)  
0.300 (7.62)  
PIN 1  
0.100 (2.54)  
1.27 (0.0500)  
BSC  
0.50 (0.0196)  
0.25 (0.0099)  
BSC  
× 45°  
0.060 (1.52)  
MAX  
0.195 (4.95)  
0.130 (3.30)  
0.115 (2.92)  
1.75 (0.0688)  
1.35 (0.0532)  
0.210  
(5.33)  
MAX  
0.25 (0.0098)  
0.10 (0.0040)  
0.015  
(0.38)  
MIN  
0.150 (3.81)  
0.130 (3.30)  
0.115 (2.92)  
0.015 (0.38)  
GAUGE  
8°  
0.51 (0.0201)  
0.31 (0.0122)  
0.014 (0.36)  
0.010 (0.25)  
0.008 (0.20)  
0° 1.27 (0.0500)  
PLANE  
COPLANARITY  
0.10  
0.25 (0.0098)  
0.17 (0.0067)  
SEATING  
PLANE  
SEATING  
PLANE  
0.40 (0.0157)  
0.022 (0.56)  
0.430 (10.92)  
MAX  
0.005 (0.13)  
MIN  
0.018 (0.46)  
0.014 (0.36)  
COMPLIANT TO JEDEC STANDARDS MS-012-AA  
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS  
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR  
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.  
0.070 (1.78)  
0.060 (1.52)  
0.045 (1.14)  
COMPLIANT TO JEDEC STANDARDS MS-001-BA  
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS  
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR  
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.  
CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS.  
Figure 33. 8-Lead Plastic Dual In-Line Package [PDIP]  
(N-8)  
Figure 35. 8-Lead Standard Small Outline Package [SOIC_N]  
Narrow Body  
(R-8)  
Dimensions shown in inches and (millimeters)  
Dimensions shown in millimeters and (inches)  
0.800 (20.32)  
0.790 (20.07)  
0.780 (19.81)  
10.50 (0.4134)  
10.10 (0.3976)  
16  
1
9
8
0.280 (7.11)  
0.250 (6.35)  
0.240 (6.10)  
16  
1
9
8
7.60 (0.2992)  
7.40 (0.2913)  
0.325 (8.26)  
0.310 (7.87)  
0.300 (7.62)  
PIN 1  
0.100 (2.54)  
10.65 (0.4193)  
10.00 (0.3937)  
BSC  
0.060 (1.52)  
MAX  
0.195 (4.95)  
0.130 (3.30)  
0.115 (2.92)  
0.210  
(5.33)  
MAX  
0.015  
(0.38)  
MIN  
0.150 (3.81)  
0.015 (0.38)  
GAUGE  
PLANE  
1.27 (0.0500)  
0.130 (3.30)  
0.115 (2.92)  
0.75 (0.0295)  
0.25 (0.0098)  
2.65 (0.1043)  
2.35 (0.0925)  
0.014 (0.36)  
0.010 (0.25)  
0.008 (0.20)  
BSC  
× 45°  
SEATING  
PLANE  
0.30 (0.0118)  
0.10 (0.0039)  
0.022 (0.56)  
0.430 (10.92)  
MAX  
0.005 (0.13)  
MIN  
0.018 (0.46)  
0.014 (0.36)  
8°  
0°  
0.070 (1.78)  
0.060 (1.52)  
0.045 (1.14)  
0.51 (0.0201)  
0.31 (0.0122)  
SEATING  
PLANE  
COPLANARITY  
0.10  
1.27 (0.0500)  
0.40 (0.0157)  
0.33 (0.0130)  
0.20 (0.0079)  
COMPLIANT TO JEDEC STANDARDS MS-001-AB  
COMPLIANT TO JEDEC STANDARDS MS-013-AA  
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS  
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR  
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.  
CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS.  
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS  
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR  
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.  
Figure 36. 16-Lead Standard Small Outline Package [SOIC_W]  
Figure 34. 16-Lead Plastic Dual In-Line Package [PDIP]  
(N-16)  
Wide Body  
(RW-16)  
Dimensions shown in inches and (millimeters)  
Dimensions shown in millimeters and (inches)  
Rev. A | Page 18 of 20  
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
5.10  
5.00  
4.90  
10.00 (0.3937)  
9.80 (0.3858)  
16  
1
9
8
6.20 (0.2441)  
5.80 (0.2283)  
4.00 (0.1575)  
3.80 (0.1496)  
16  
9
4.50  
4.40  
4.30  
6.40  
BSC  
1.75 (0.0689)  
1.35 (0.0531)  
1.27 (0.0500)  
BSC  
0.50 (0.0197)  
0.25 (0.0098)  
× 45°  
0.25 (0.0098)  
0.10 (0.0039)  
1
8
PIN 1  
8°  
0°  
0.51 (0.0201)  
0.31 (0.0122)  
SEATING  
PLANE  
1.27 (0.0500)  
0.40 (0.0157)  
COPLANARITY  
0.10  
0.25 (0.0098)  
0.17 (0.0067)  
1.20  
MAX  
0.15  
0.05  
0.20  
0.09  
0.75  
0.60  
0.45  
COMPLIANT TO JEDEC STANDARDS MS-012-AC  
8°  
0°  
0.30  
0.19  
0.65  
BSC  
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS  
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR  
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.  
SEATING  
PLANE  
COPLANARITY  
0.10  
COMPLIANT TO JEDEC STANDARDS MO-153-AB  
Figure 37. 16-Lead Standard Small Outline Package [SOIC_N]  
Figure 38. 16-Lead Thin Shrink Small Outline Package [TSSOP]  
(RU-16)  
Narrow Body  
(R-16)  
Dimensions shown in millimeters  
Dimensions shown in millimeters and (inches)  
ORDERING GUIDE  
Model  
ADM8690AN  
ADM8690ANZ1  
Temperature Range  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
Package Description  
Package Option  
8-Lead Plastic Dual In-Line Package [PDIP]  
8-Lead Plastic Dual In-Line Package [PDIP]  
8-Lead Standard Small Outline Package [SOIC_N]  
8-Lead Standard Small Outline Package [SOIC_N]  
8-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Plastic Dual In-Line Package [PDIP]  
N-8  
N-8  
R-8  
R-8  
ADM8690ARN  
ADM8690ARN-REEL  
ADM8690ARNZ1  
ADM8691AN  
ADM8691ANZ1  
ADM8691ARN  
ADM8691ARN-REEL  
ADM8691ARNZ1  
ADM8691ARW  
ADM8691ARW-REEL  
ADM8691ARWZ1  
ADM8691ARU  
ADM8691ARU-REEL  
ADM8691ARUZ1  
ADM8692AN  
ADM8692ANZ1  
ADM8692ARN  
ADM8692ARN-REEL  
ADM8692ARNZ1  
ADM8693AN  
ADM8693ANZ1  
ADM8693ARN  
R-8  
N-16  
N-16  
R-16  
R-16  
R-16  
RW-16  
RW-16  
RW-16  
RU-16  
RU-16  
RU-16  
N-8  
16-Lead Plastic Dual In-Line Package [PDIP]  
16-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Thin Shrink Small Outline Package [TSSOP]  
16-Lead Thin Shrink Small Outline Package [TSSOP]  
16-Lead Thin Shrink Small Outline Package [TSSOP]  
8-Lead Plastic Dual In-Line Package [PDIP]  
8-Lead Plastic Dual In-Line Package [PDIP]  
N-8  
R-8  
R-8  
R-8  
8-Lead Standard Small Outline Package [SOIC_N]  
8-Lead Standard Small Outline Package [SOIC_N]  
8-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Plastic Dual In-Line Package [PDIP]  
N-16  
N-16  
R-16  
R-16  
R-16  
RW-16  
RW-16  
RW-16  
RU-16  
RU-16  
RU-16  
16-Lead Plastic Dual In-Line Package [PDIP]  
16-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Thin Shrink Small Outline Package [TSSOP]  
16-Lead Thin Shrink Small Outline Package [TSSOP]  
16-Lead Thin Shrink Small Outline Package [TSSOP]  
ADM8693ARN-REEL  
ADM8693ARNZ1  
ADM8693ARW  
ADM8693ARW-REEL  
ADM8693ARWZ1  
ADM8693ARU  
ADM8693ARU-REEL  
ADM8693ARUZ1  
Rev. A | Page 19 of 20  
 
 
ADM8690/ADM8691/ADM8692/ADM8693/ADM8694/ADM8695  
Model  
Temperature Range  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
Package Description  
Package Option  
ADM8694AN  
8-Lead Plastic Dual In-Line Package [PDIP]  
8-Lead Plastic Dual In-Line Package [PDIP]  
8-Lead Standard Small Outline Package [SOIC_N]  
8-Lead Standard Small Outline Package [SOIC_N]  
8-Lead Standard Small Outline Package [SOIC_N]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Standard Small Outline Package [SOIC_W]  
16-Lead Standard Small Outline Package [SOIC_W]  
N-8  
N-8  
R-8  
R-8  
ADM8694ANZ1  
ADM8694ARN  
ADM8694ARN-REEL  
ADM8694ARNZ1  
ADM8695ARW  
ADM8695ARW-REEL  
ADM8695ARWZ1  
R-8  
RW-16  
RW-16  
RW-16  
1 Z = Pb-free part.  
©2006 Analog Devices, Inc. All rights reserved. Trademarks and  
registered trademarks are the property of their respective owners.  
C00093-0-9/06(A)  
Rev. A | Page 20 of 20  
 
 

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