DS1706LESA/T&R [MAXIM]
Power Supply Management Circuit, Fixed, 1 Channel, CMOS, PDSO8, 0.150 INCH, SOIC-8;型号: | DS1706LESA/T&R |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Power Supply Management Circuit, Fixed, 1 Channel, CMOS, PDSO8, 0.150 INCH, SOIC-8 光电二极管 |
文件: | 总11页 (文件大小:207K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
DS1705/DS1706
www.maxim-ici.com
FEATURES
PIN ASSIGNMENT
CꢀHalts and restarts an out-of-control
microprocessor
WDS
PBRST
1
2
3
4
8
7
6
5
VCC
RST
ST
CꢀHolds microprocessor in check during power
transients
GND
IN
CꢀAutomatically restarts microprocessor after
power failure
NMI
8-Pin DIP (300 -mil)
CꢀMonitors pushbutton for external override
CꢀAccurate 5%, 10% or 20% resets for 3.3V
systems and 5% or 10% resets for 5.0V
systems
WDS
1
2
3
4
8
7
6
5
PBRST
VCC
RST(*RST)
ST
GND
IN
CꢀEliminates the need for discrete components
Cꢀ3.3V 20% tolerance for use with 3.0V
systems
NMI
8-Pin SOIC (150-mil)
CꢀPin-compatible with the MAXIM
MAX705/MAX706 in 8-pin DIP, 8-pin SOIC,
and ꢀ-SOP
RST(*RST)
WDS
ST
1
2
3
4
8
7
6
5
NMI
PBRST
VCC
IN
GND
Cꢀ8-pin DIP, 8-pin SOIC and 8-pin ꢀ-SOP
packages
8-Pin ꢀ-SOP (118-mil)
See Mech. Drawings Section on website
CꢀIndustrial temperature range -40LC to +85LC
DS1705 and DS1706_R/S/T
(*DS1706L and DS1706P)
PIN DESCRIPTION
PBRST
VCC
- Pushbutton Reset Input
- Power Supply
- Ground
GND
IN
- Input
NMI
- Non-maskable Interrupt
- Strobe Input
ST
RST
*RST
- Active Low Reset Output
- Active High Reset Output
(DS1706P and DS1706L only)
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
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040405
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.
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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
40kꢀ
180kꢀ
PUSH-BUTTON RESET Figure 2
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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
R1ꢀ R2
V
V
SENSE
VSENSE
=
X 1.25
VMAX
=
X VCC
R2
TP
Example:
VSENSE = 4.50V at the trip point
V
CC = 3.3V
10 kΩ = R2
4.50
1.25
Therefore:
X 3.3 = 11.88V maximum
R1ꢀ10k
4.5 =
X 1.25
R1 = 26 kΩ
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DS1705/DS1706
WATCHDOG TIMER Figure 6
TIMING DIAGRAM: STROBE INPUT Figure 7
TIMING DIAGRAM: NON-MASKABLE INTERRUPT Figure 8
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DS1705/DS1706
TIMING DIAGRAM: POWER-DOWN Figure 9
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DS1705/DS1706
TIMING DIAGRAM: POWER-UP Figure 10
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DS1705/DS1706
ABSOLUTE MAXIMUM RATINGS*
Voltage on VCC Pin Relative to Ground
Voltage on I/O Relative to Ground**
Operating Temperature
-0.5V to +7.0V
-0.5V to VCC + 0.5V
-40LC to +85LC
Storage Temperature
-55LC to +125LC
260LC for 10 seconds
Soldering Temperature
* 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
(-40LC to +85LC)
PARAMETER
SYMBOL
VCC
MIN
1.2
TYP
MAX
5.5
UNITS NOTES
Supply Voltage
V
1
VIH
2.0
VCC-0.5
-0.03
VCC+0.3
V
1, 3
1, 4
1
ST and PBRST Input High Level
VIL
+0.5
V
ST and PBRST Input Low Level
DC ELECTRICAL CHARACTERISTICS
(-40LC to +85LC; VCC=1.2V to 5.5V)
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
V
V
V
ꢀA
ꢀA
mA
V
1
1
1
1
1
2
3
3
3
5
Output Current @ 2.4V
Output Current @ 0.4V
Output Voltage @ -500 ꢀA
Operating Current
IOH
IOL
VOH
ICC
350
10
VCC-0.3 VCC-0.1
60
50
ꢀA
@ VCC < 5.5V
Operating Current
ICC
5
ꢀA
@ VCC < 3.6V
IN Input Trip Point
VTP
1.20
1.25
1.30
V
1
CAPACITANCE
PARAMETER
Input Capacitance
(tA=25ꢀC)
SYMBOL
CIN
MIN
TYP
MAX
UNITS NOTES
5
pF
Output Capacitance
COUT
7
pF
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DS1705/DS1706
AC ELECTRICAL CHARACTERISTICS
(-40LC to +85LC; VCC=1.2V to 5.5V)
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
tPDLY
0
ns
ns
PBRST Stable Low to RST and RST
Watchdog Timeout
tTD
tIPD
1.0
1.6
5
2.2
8
s
ꢀs
8
9
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 kꢁꢂtypical and the ST input is
internally pulled up to VCC with an internal impedance of 180 kꢁꢂtypical.
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 ꢃ pulses < 2 ꢀs at VCCTP minimum will not cause a reset.
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DS1705/DS1706
PART MARKING CODES
DS170AB
yywwrv
###xx
8-pin DIP
(300 MIL)
cccccc
DS170AB
yywwrv
###xx
8-pin SOIC
(150 MIL)
cccccc
8-pin µSOP
(118 MIL)
170AB
###xx
ywwrv
Brand Codes
Code
Description
Values
AB
Device type and tolerance
5_, 6_, 6L, 6P, 6R, 6S, 6T (where’_’ is a blank)
y, the last digit of the year.
yww or yyww Date Code. Identifies the
year and work week the
yy, the last two digits of the year.
device was assembled.
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
Die Revision
###xx
cccccc
Lot Code
Country of Assembly
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DS1705/DS1706
ORDERING INFORMATION
ORDERING
NUMBER
PACKAGE
OPERATING
VERSION
TEMPERATURE
DS1705EPA
DS1705ESA
DS1705EUA
DS1706EPA
DS1706ESA
DS1706EUA
DS1706LEPA
DS1706LESA
DS1706LEUA
8-pin DIP (300mil)
8-pin SOIC (150 mil)
8-pin µSOP (118 mil)
8-pin DIP (300mil)
8-pin SOIC (150 mil)
8-pin µSOP (118 mil)
8-pin DIP (300mil)
8-pin SOIC (150 mil)
8-pin µSOP (118 mil)
-40°C TO +85°C 5V-5% MONITOR, /RST, /WDS
-40°C TO +85°C 5V-5% MONITOR, /RST, /WDS
-40°C TO +85°C 5V-5% MONITOR, /RST, /WDS
-40°C TO +85°C 5V-10% MONITOR, /RST, /WDS
-40°C TO +85°C 5V-10% MONITOR, /RST, /WDS
-40°C TO +85°C 5V-10% MONITOR, /RST, /WDS
-40°C TO +85°C 5V-5% MONITOR, RST, /WDS
-40°C TO +85°C 5V-5% MONITOR, RST, /WDS
-40°C TO +85°C 5V-5% MONITOR, RST, /WDS
-40°C TO +85°C 3.3V-20% MONITOR, RST, /WDS
-40°C TO +85°C 3.3V-20% MONITOR, RST, /WDS
-40°C TO +85°C 3.3V-20% MONITOR, RST, /WDS
-40°C TO +85°C 3.3V-20% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-20% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-20% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-10% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-10% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-10% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-5% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-5% MONITOR, /RST, /WDS
-40°C TO +85°C 3.3V-5% MONITOR, /RST, /WDS
DS1706PEPA 8-pin DIP (300mil)
DS1706PESA 8-pin SOIC (150 mil)
DS1706PEUA 8-pin µSOP (118 mil)
DS1706REPA 8-pin DIP (300mil)
DS1706RESA 8-pin SOIC (150 mil)
DS1706REUA 8-pin µSOP (118 mil)
DS1706SEPA 8-pin DIP (300mil)
DS1706SESA 8-pin SOIC (150 mil)
DS1706SEUA 8-pin µSOP (118 mil)
DS1706TEPA
DS1706TESA
8-pin DIP (300mil)
8-pin SOIC (150 mil)
DS1706TEUA 8-pin µSOP (118 mil)
* Contact factory for availability of Pb-free versions.
E = -40°C to +85°C temperature range
A = 8 lead device
P = Plastic DIP (300 mil)
S = SOIC (150 mil)
U = µSOP (118 mil)
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