DS1708TEUA [MAXIM]
3.3 and 5.0-Volt MicroMonitor; 3.3和5.0伏MicroMonitor
| 型号： | DS1708TEUA |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 3.3 and 5.0-Volt MicroMonitor |
| 文件： | 总10页 (文件大小：182K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS1707/DS1708
www.maxim-ic.com
FEATURES
PIN ASSIGNMENT
CꢀHolds microprocessor in check during power
transients
RST
PBRST
1
2
3
4
8
7
6
5
VCC
RST
NC
CꢀAutomatically restarts microprocessor after
power failure
GND
IN
CꢀMonitors pushbutton for external override
CꢀAccurate 5%, 10% or 20% resets for 3.3V
systems and 5% or 10% resets for 5.0V
systems
NMI
8-Pin DIP (300-mil)
RST
1
2
3
4
8
7
6
5
PBRST
VCC
CꢀEliminates the need for discrete components
Cꢀ20% tolerance compatible with 3.0V systems
CꢀPin compatible with the MAXIM
MAX707/MAX708 in 8-pin DIP, 8-pin SOIC
packages
RST
NC
GND
IN
NMI
8-Pin SOIC (150-mil)
Cꢀ8-pin DIP, 8-pin and ꢀ-SOP SOIC and 8-pin
ꢀ-SOP packages available
CꢀIndustrial temperature range -40LC to +85LC
RST
NC
1
2
3
4
8
7
6
5
RST
PBRST
VCC
NMI
IN
GND
8-Pin ꢀ-SOP (118-mil)
See Mech. Drawings Section on website
DS1707 and DS1708_R/S/T
PIN DESCRIPTION
PBRST
VCC
- Pushbutton Reset Input
- Power Supply
- Ground
GND
IN
- Input
NMI
NC
- Non-maskable Interrupt
- No Connect
RST
RST
- Active Low Reset Output
- Active High Reset Output
DESCRIPTION
The DS1707/DS1708 3.3- or 5.0-Volt MicroMonitor monitors three vital conditions for a microprocessor:
power supply, voltage sense, 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
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.
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041305
DS1707/DS1708
The third function the DS1707/DS1708 performs is pushbutton reset control. The DS1707/DS1708
debounces the pushbutton input and guarantees an active reset pulse width of 130 ms minimum.
OPERATION
Power Monitor
The DS1707/DS1708 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 and RST signals. RST and RST are excellent control signals for a microprocessor, as
processing is stopped at the last possible moment of valid VCC. On power-up, RST and RST are kept
active for a minimum of 130 ms to allow the power supply and processor to stabilize.
Pushbutton Reset
The DS1707/DS1708 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 RST and RST signals 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 NMI output to the PBRST input as shown in Figure 3.
Non-Maskable Interrupt
The DS1707/DS1708 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 DS1707/DS1708 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 shut-down between NMI and RST/ RST .
When the supply being monitored decays to the voltage sense point, the DS1707/DS1708 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 the 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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DS1707/DS1708
MICROMONITOR BLOCK DIAGRAM Figure 1
40kꢀ
PUSHBUTTON RESET Figure 2
PUSHBUTTON RESET CONTROLLED BY NMI Figure 3
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DS1707/DS1708
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
VCC = 3.3V
10 kΩ = R2
4.50
1.25
Therefore:
X 3.3 = 11.88V maximum
R1ꢀ10k
4.50 =
X 1.25
R1 = 26 kΩ
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DS1707/DS1708
TIMING DIAGRAM: NON-MASKABLE INTERRUPT Figure 6
TIMING DIAGRAM: POWER-DOWN Figure 7
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DS1707/DS1708
TIMING DIAGRAM: POWER UP Figure 8
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DS1707/DS1708
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 limits on IN 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
PBRST Input High Level
VIL
+0.5
V
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 DS1707
VCC Trip Point DS1708
VCC Trip Point DS1708T
VCC Trip Point DS1708S
VCC Trip Point DS1708R
Input Leakage
V
V
V
V
1
1
1
1
1
2
3
3
3
5
5
1
V
ꢀA
ꢀA
mA
V
Output Current @ 2.4V
Output Current @ 0.4V
Output Voltage @ -500µA
Operating Current @ VCC < 5.5V
Operating Current @ VCC < 3.6V
IN Input Trip Point
IOH
IOL
VOH
ICC
ICC
VTP
350
10
VCC-0.3 VCC-0.1
60
50
1.30
ꢀA
ꢀA
V
1.20
1.25
CAPACITANCE
PARAMETER
Input Capacitance
Output Capacitance
(tA=25LC)
SYMBOL
CIN
MIN
TYP
MAX
UNITS NOTES
5
7
pF
pF
COUT
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DS1707/DS1708
AC ELECTRICAL CHARACTERISTICS
(-40LC to +85LC; VCC=1.2V to 5.5V)
PARAMETER
SYMBOL MIN
TYP
MAX
UNITS NOTES
tPB
150
ns
PBRST = VIL
Reset Active Time
tRST
tRPD
130
205
5
285
8
ms
ꢀs
7
6
VCC Detect to RST and RST
VCC Slew Rate
tF
20
ꢀs
tRPU
130
205
5
285
ms
VCC Detect to RST and RST
VCC Slew Rate
tR
tPDLY
0
ns
ns
250
8
PBRST Stable Low to RST and RST
VIN Detect to NMI
tIPD
7
ꢀs
NOTES:
1. All voltages are referenced to ground.
2. PBRST is internally pulled up to VCC with an internal impedance of 40 kꢁ typical.
3. VCC ≥ 2.4V
4. VCC < 2.4V
5. Measured with outputs open and all inputs at VCC or ground.
6. tR = 5 ꢀs
7. Noise immunity - pulses < 2 ꢀs at VCCTP minimum will not cause a reset.
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DS1707/DS1708
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
7_, 8_, 8R, 8S, 8T (where’_’ is a blank)
AB
Device type and tolerance
yww or yyww Date Code. Identifies the year and y, the last digit of the year.
work 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
Die Revision
###xx
cccccc
Lot Code
Country of Assembly
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DS1707/DS1708
ORDERING INFORMATION
ORDERING
NUMBER
PACKAGE
OPERATING
VERSION
TEMPERATURE
DS1707EPA
DS1707ESA
DS1707EUA
DS1708EPA
DS1708ESA
DS1708EUA
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, RST
-40°C TO +85°C 5V-5% MONITOR, /RST, RST
-40°C TO +85°C 5V-5% MONITOR, /RST, RST
-40°C TO +85°C 5V-10% MONITOR, /RST, RST
-40°C TO +85°C 5V-10% MONITOR, /RST, RST
-40°C TO +85°C 5V-10% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-20% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-20% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-20% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-10% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-10% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-10% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-5% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-5% MONITOR, /RST, RST
-40°C TO +85°C 3.3V-5% MONITOR, /RST, RST
DS1708REPA 8-pin DIP (300mil)
DS1708RESA 8-pin SOIC (150 mil)
DS1708REUA 8-pin µSOP (118 mil)
DS1708SEPA 8-pin DIP (300mil)
DS1708SESA 8-pin SOIC (150 mil)
DS1708SEUA 8-pin µSOP (118 mil)
DS1708TEPA
DS1708TESA
8-pin DIP (300mil)
8-pin SOIC (150 mil)
DS1708TEUA 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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