DS1706ESA+T&R [MAXIM]
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| 型号： | DS1706ESA+T&R |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 暂无描述 |
| 文件： | 总12页 (文件大小：255K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-5212; Rev 4/10
DS1705/DS1706
3.3V and 5.0V MicroMonitor
www.maxim-ic.com
FEATURES
PIN ASSIGNMENT
. Halts and restarts an out-of-control
microprocessor
WDS
1
2
3
4
8
7
6
5
PBRST
VCC
RST
ST
. Holds microprocessor in check during power
transients
. Automatically restarts microprocessor after
power failure
GND
IN
NMI
8-Pin DIP (300 -mil)
. Monitors pushbutton for external override
. Accurate 5%, 10% or 20% resets for 3.3V
systems and 5% or 10% resets for 5.0V
systems
. Eliminates the need for discrete components
. 3.3V 20% tolerance for use with 3.0V
systems
WDS
1
8
PBRST
VCC
2
3
4
7
6
5
RST(*RST)
ST
GND
IN
NMI
8-Pin SOIC (150-mil)
. Pin-compatible with the MAXIM
MAX705/MAX706 in 8-pin DIP, 8-pin SOIC,
and -SOP
RST(*RST)
WDS
ST
NMI
IN
1
2
3
4
8
7
6
5
PBRST
VCC
GND
. 8-pin DIP, 8-pin SOIC and 8-pin -SOP
8-Pin -SOP (118-mil)
See Mech. Drawings Section on website
packages
. Industrial temperature range -40C to +85C
DS1705 and DS1706_R/S/T
(*DS1706L and DS1706P)
PIN DESCRIPTION
PBRST
- Pushbutton Reset Input
- Power Supply
- Ground
VCC
GND
IN
- Input
NMI
ST
- Non-maskable Interrupt
- Strobe Input
RST
- Active Low Reset Output
- Active High Reset Output
(DS1706P and DS1706L only)
*RST
WDS
- Watchdog Status Output
DESCRIPTION
The DS1705/DS1706 3.3- or 5.0-Volt MicroMonitor monitors three vital conditions for a microprocessor:
power supply, software execution, and external override. A precision temperature compensated reference
and comparator circuit monitor the status of VCC at the device and at an upstream point for maximum
protection. When the sense input detects an out-of-tolerance condition, a non-maskable interrupt is
generated. As the voltage at the device degrades, an internal power fail signal is generated which forces
1 of 12
DS1705/DS1706
the reset to an active state. When VCC returns to an in-tolerance condition, the reset signal is kept in the
active state for a minimum of 130 ms to allow the power supply and processor to stabilize.
The second function the DS1705/DS1706 performs is pushbutton reset control. The DS1705/DS1706
debounces the pushbutton input and guarantees an active reset pulse width of 130 ms minimum.
The third function is a watchdog timer. The DS1705/DS1706 has an internal timer that forces the WDS
output signal to the active state if the strobe input is not driven low prior to time-out.
OPERATION
Power Monitor
The DS1705/DS1706 detects out-of-tolerance power supply conditions and warns a processor-based
system of impending power failure. When VCC falls below the minimum VCC tolerance, a comparator
outputs the RST (or RST) signal. RST (or RST) is an excellent control signal for a microprocessor, as
processing is stopped at the last possible moment of valid VCC. On power-up, RST (or RST) are kept
active for a minimum of 130 ms to allow the power supply and processor to stabilize.
Pushbutton Reset
The DS1705/DS1706 provides an input pin for direct connection to a pushbutton reset (see Figure 2). The
pushbutton reset input requires an active low signal. Internally, this input is debounced and timed such
that a RST (or RST) signal of at least 130 ms minimum will be generated. The 130 ms delay commences
as the pushbutton reset input is released from the low level. The pushbutton can be initiated by connecting
the WDS or NMI outputs to the PBRST input as shown in Figure 3.
Non-Maskable Interrupt
The DS1705/DS1706 generates a non-maskable interrupt ( NMI ) for early warning of a power failure. A
precision comparator monitors the voltage level at the IN pin relative to an on-chip reference generated
by an internal band gap. The IN pin is a high impedance input allowing for a user-defined sense point. An
external resistor voltage divider network (Figure 5) is used to interface with high voltage signals. This
sense point may be derived from a regulated supply or from a higher DC voltage level closer to the main
system power input. Since the IN trip point VTP is 1.25 volts, the proper values for R1 and R2 can be
determined by the equation as shown in Figure 5. Proper operation of the DS1705/DS1706 requires that
the voltage at the IN pin be limited to VCC. Therefore, the maximum allowable voltage at the supply being
monitored (VMAX) can also be derived as shown in Figure 5. A simple approach to solving the equation is
to select a value for R2 high enough to keep power consumption low, and solve for R1. The flexibility of
the IN input pin allows for detection of power loss at the earliest point in a power supply system,
maximizing the amount of time for system shutdown between NMI and RST (or RST).
When the supply being monitored decays to the voltage sense point, the DS1705/DS1706 pulses the NMI
output to the active state for a minimum 200 s. The NMI power-fail detection circuitry also has built-in
hysteresis of 100 V. The supply must be below the voltage sense point for approximately 5 s before a
low NMI will be generated. In this way, power supply noise is removed from the monitoring function,
preventing false interrupts. During a power-up, any detected IN pin levels below VTP by the comparator
are disabled from generating an interrupt until VCC rises to VCCTP. As a result, any potential NMI pulse
will not be initiated until VCC reaches VCCTP
.
Connecting NMI to PBRST would allow non-maskable interrupt to generate an automatic reset when an
out-of-tolerance condition occurred in a monitored supply. An example is shown in Figure 3.
2 of 12
DS1705/DS1706
Watchdog Timer
The watchdog timer function forces WDS signals active when the ST input is not clocked within the 1
second time-out period. Time-out of the watchdog starts when RST (or RST) becomes inactive. If a high-
to-low transition occurs on the ST input pin prior to time-out, the watchdog timer is reset and begins to
time out again. If the watchdog timer is allowed to time out, the WDS signal is driven active (low) for a
minimum of 130 ms. The ST input can be derived from many microprocessor outputs. The typical signals
used are the microprocessors address signals, data signals, or control signals. When the microprocessor
functions normally, these signals would, as a matter of routine, cause the watchdog to be reset prior to
time-out. To guarantee that the watchdog timer does not time out, a high-to-low transition must occur at
or less than the minimum watchdog time-out of 1 second. A typical circuit example is shown in Figure 6.
MICROMONITOR BLOCK DIAGRAM Figure 1
40k
180k
PUSH-BUTTON RESET Figure 2
3 of 12
DS1705/DS1706
PUSH-BUTTON RESET CONTROLLED BY NMI AND WDS Figure 3
TIMING DIAGRAM: PUSHBUTTON RESET Figure 4
NON-MASKABLE INTERRUPT CIRCUIT EXAMPLE Figure 5
R1 R2
V
SENSE
VSENSE
=
X 1.25
VMAX
=
X VCC
R2
V
TP
Example:
VSENSE = 4.50V at the trip point
CC = 3.3V
V
10 kΩ = R2
4.50
Therefore:
X 3.3 = 11.88V maximum
1.25
R110k
4.5 =
X 1.25
R1 = 26 kΩ
10k
4 of 12
DS1705/DS1706
WATCHDOG TIMER Figure 6
TIMING DIAGRAM: STROBE INPUT Figure 7
TIMING DIAGRAM: NON-MASKABLE INTERRUPT Figure 8
5 of 12
DS1705/DS1706
TIMING DIAGRAM: POWER-DOWN Figure 9
6 of 12
DS1705/DS1706
TIMING DIAGRAM: POWER-UP Figure 10
7 of 12
DS1705/DS1706
ABSOLUTE MAXIMUM RATINGS
Voltage Range on VCC Pin Relative to Ground
Voltage Range on I/O Relative to Ground*
Operating Temperature Range
Storage Temperature Range
Lead Temperature (soldering, 10s)
Soldering Temperature (reflow)
Lead(Pb)-free
-0.5V to +7.0V
-0.5V to (VCC + 0.5V)
-40C to +85C
-55C to +125C
+260C
+260C
+240C
Containing lead(Pb)
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect
reliability.
*The voltage input on IN, ST, and PBRST can be exceeded if the input current is less than 10 mA.
RECOMMENDED DC OPERATING CONDITIONS
(TA = -40C to +85C)
MAX UNITS NOTES
PARAMETER
SYMBOL
VCC
MIN
1.2
TYP
Supply Voltage
5.5
V
V
1
VIH
2.0
VCC+0.3
1, 3
1, 4
1
ST and PBRST Input High Level
VCC-0.5
-0.03
VIL
+0.5
V
ST and PBRST Input Low Level
DC ELECTRICAL CHARACTERISTICS
(VCC = 1.2V to 5.5V, TA = -40C to +85C.)
PARAMETER
SYMBOL
VCCTP
VCCTP
VCCTP
VCCTP
VCCTP
IIL
MIN
4.50
4.25
3.00
2.85
2.55
-1.0
TYP
4.65
4.40
3.08
2.93
2.63
MAX
4.75
4.50
3.15
3.00
2.70
+1.0
UNITS NOTES
VCC Trip Point DS1705/DS1706L
VCC Trip Point DS1706
VCC Trip Point DS1706T
VCC Trip Point DS1706S
VCC Trip Point DS1706P or R
Input Leakage
V
V
1
1
1
1
1
2
3
3
3
5
V
V
V
A
A
mA
V
Output Current @ 2.4V
Output Current @ 0.4V
Output Voltage @ -500 A
Operating Current
IOH
350
IOL
10
VOH
VCC-0.3 VCC-0.1
ICC
60
50
A
@ VCC < 5.5V
Operating Current
ICC
5
1
A
@ VCC < 3.6V
IN Input Trip Point
VTP
1.20
1.25
1.30
V
CAPACITANCE
PARAMETER
(TA = +25C)
UNITS NOTES
SYMBOL
CIN
MIN
TYP
MAX
Input Capacitance
Output Capacitance
5
7
pF
pF
COUT
8 of 12
DS1705/DS1706
AC ELECTRICAL CHARACTERISTICS
(VCC = 1.2V to 5.5V, TA = -40C to +85C.)
PARAMETER
SYMBOL MIN
TYP
205
5
MAX
285
8
UNITS NOTES
tPB
150
ns
PBRST = VIL
Reset Active Time
tRST
tST
130
10
ms
ns
6
9
ST Pulse Width
tRPD
s
VCC Detect to RST and RST
VCC Slew Rate
tF
20
s
tRPU
130
205
285
250
ms
7
VCC Detect to RST and RST
VCC Slew Rate
tR
0
ns
ns
tPDLY
PBRST Stable Low to RST and RST
Watchdog Timeout
tTD
1.0
1.6
5
2.2
8
s
8
9
tIPD
s
VIN Detect to NMI
NOTES:
1. All voltages are referenced to ground.
2. PBRST is internally pulled up to VCC with an internal impedance of 40 ktypical and the ST input is
internally pulled up to VCC with an internal impedance of 180 ktypical.
3. VCC ≥ 2.4V.
4. VCC < 2.4V.
5. Measured with outputs open and all inputs at VCC or ground.
6. Must not exceed tTD minimum.
7. tR = 5 s.
8. Minimum watchdog time-out tested at 2.7V for the 3.3V devices and 4.5V for the 5.0V devices.
9. Noise immunity pulses < 2 s will not cause a reset.
9 of 12
DS1705/DS1706
PART MARKING CODES
DS170AB
yywwrv
8-pin DIP
(300 MIL)
cccccc
###xx
DS170AB
yywwrv
###xx
8-pin SOIC
(150 MIL)
cccccc
8-pin µSOP
(118 MIL)
170AB
ywwrv
###xx
BRAND CODES
DESCRIPTION
Device type and tolerance
Date Code. Identifies the year and work y, the last digit of the year.
CODE
VALUES
5_, 6_, 6L, 6P, 6R, 6S, 6T (where’_’ is a blank)
AB
yww or yyww
week the device was assembled.
yy, the last two digits of the year.
ww, the work week (values 01 through 52).
A letter followed by a number (eg. B1)
Three numbers followed by 2 letters
Abbreviation of country name.
rv
###xx
cccccc
Die Revision
Lot Code
Country of Assembly
10 of 12
DS1705/DS1706
VERSION
ORDERING INFORMATION
PART
TEMP 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
PIN-PACKAGE
DS1705EPA
DS1705ESA
DS1705EUA
DS1706EPA
DS1706ESA
DS1706EUA
DS1706LEPA
DS1706LESA
DS1706LEUA
DS1706PEPA
DS1706PESA
DS1706PEUA
DS1706REPA
DS1706RESA
DS1706REUA
DS1706SEPA
DS1706SESA
DS1706SEUA
DS1706TEPA
DS1706TESA
DS1706TEUA
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
8-pin PDIP (300 mils)
8-pin SO (150 mils)
8-pin µSOP (118 mils)
5V-5% MONITOR, /RST, /WDS
5V-5% MONITOR, /RST, /WDS
5V-5% MONITOR, /RST, /WDS
5V-10% MONITOR, /RST, /WDS
5V-10% MONITOR, /RST, /WDS
5V-10% MONITOR, /RST, /WDS
5V-5% MONITOR, RST, /WDS
5V-5% MONITOR, RST, /WDS
5V-5% MONITOR, RST, /WDS
3.3V-20% MONITOR, RST, /WDS
3.3V-20% MONITOR, RST, /WDS
3.3V-20% MONITOR, RST, /WDS
3.3V-20% MONITOR, /RST, /WDS
3.3V-20% MONITOR, /RST, /WDS
3.3V-20% MONITOR, /RST, /WDS
3.3V-10% MONITOR, /RST, /WDS
3.3V-10% MONITOR, /RST, /WDS
3.3V-10% MONITOR, /RST, /WDS
3.3V-5% MONITOR, /RST, /WDS
3.3V-5% MONITOR, /RST, /WDS
3.3V-5% MONITOR, /RST, /WDS
Note: Devices are also available in a lead(Pb)-free/RoHS-compliant package. Specify lead-free by adding a plus (+) to the part number
when ordering.
E = -40°C to +85°C temperature range
A = 8-lead device
P = Plastic DIP (300 mils)
S = SO (150 mils)
U = µSOP (118 mils)
PACKAGE INFORMATION
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-”
in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
8 PDIP
PACKAGE CODE
DOCUMENT NO.
21-0043
P8-2
S8-2
U8-1
8 SO
21-0041
21-0036
8 SOP
11 of 12
DS1705/DS1706
REVISION HISTORY
REVISION
PAGES
CHANGED
DESCRIPTION
DATE
Added the lead temperature and updated the soldering
temperature in the Absolute Maximum Ratings; corrected Note 9.
4/10
8, 9
12 of 12
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim
reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Maxim Integrated Products, Inc.
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