DS1232LPS ,Low power micromonitor chipPIN DESCRIPTIONPBRST – Pushbutton Reset InputTD – Time Delay SetTOL – Selects 5% or 10% V DetectCCG ..
DS1232LPS-2 ,Low power micromonitor chipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DS1232LPS-2+ ,Low-Power MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 5% or 10% V DetectCCG ..
DS1232LPS-2+T&R ,Low-Power MicroMonitor ChipFEATURES PIN ASSIGNMENT Super-low power version of DS1232VPBRST 1 8 CC NC 1 16 NC 50 μA quiescent ..
DS1232LPSN-2+ ,Low-Power MicroMonitor ChipFEATURES PIN ASSIGNMENT Super-low power version of DS1232VPBRST 1 8 CC NC 1 16 NC 50 μA quiescent ..
DS1232N ,MicroMonitor ChipFEATURES PIN ASSIGNMENT Halts and restarts an out-of-controlVCCPBRST 1 8microprocessorTD 2 ST7 Ho ..
DTA143ESA , Digital transistors (built-in resistors)
DTA143TCA ,Conductor Holdings Limited - Digital Transistor
DTA143TE ,Bias Resistor TransistorMaximum ratings applied to the device are individual stress limit values (notnormal operating condi ..
DTA143TET1 ,Bias Resistor TransistorDTA114EET1 SeriesPreferred DevicesBias Resistor TransistorsPNP Silicon Surface Mount Transistorswit ..
DTA143TM , PNP -100mA -50V Digital Transistors (Bias Resistor Built-in Transistors)
DTA143XK , DTA/DTC SERIES
DS1232LPS
Low power micromonitor chip
DS1232LP/LPSLow Power MicroMonitor Chip
DS1232LP/LPS
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FEATURESSuper low-power version of DS123250A quiescent currentHalts and restarts an out–of–control microprocessorAutomatically restarts microprocessor after power
failureMonitors pushbutton for external overrideAccurate 5% or 10% microprocessor power supply
monitoring8–pin DIP, 8–pin SOIC or space saving μ–SOP pack-
age availableOptional 16–pin SOIC package availableIndustrial temperature –40°C to +85°C available, des-
ignated N
PIN ASSIGNMENTVCC
RST
RST
PBRST
TOL
GND
DS1232LP 8–Pin DIP
(300 Mil)
See Mech. Drawings
Section
DS1232LPS 16–Pin SOIC
(300 Mil)
See Mech. Drawings
Section
TOL
GND
PBRSTVCC
RST
RST
DS1232LPS–2 8–Pin
SOIC
(150 Mil)
See Mech. Drawings
Section
PBRST
TOL
GND
VCC
RST
RST
DS1232LPμ
(118 MIL μ–SOP)
See Mech. Drawings
Section
VCC
RST
RST
PBRST
TOL
GND
PIN DESCRIPTIONPBRST–Pushbutton Reset Input–Time Delay Set
TOL–Selects 5% or 10% VCC Detect
GND–Ground
RST–Reset Output (Active High)
RST–Reset Output (Active Low, open drain)–Strobe Input
VCC–+5 Volt Power
DESCRIPTIONThe DS1232LP/LPS Low Power MicroMonitor Chip
monitors three vital conditions for a microprocessor:
power supply, software execution, and external over-
ride. First, a precision temperature–compensated refer-
ence and comparator circuit monitors the status of VCC.
When an out–of–tolerance condition occurs, an internal
power fail signal is generated which forces reset to the
active state. When VCC returns to an in-tolerance condi-
tion, the reset signals are kept in the active state for a
minimum of 250 ms to allow the power supply and pro-
cessor to stabilize.
The second function the DS1232LP/LPS performs is
pushbutton reset control. The DS1232LP/LPS de-
bounces the pushbutton input and guarantees an active
reset pulse width of 250 ms minimum. The third function
is a watchdog timer. The DS1232LP/LPS has an inter-
nal timer that forces the reset signals to the active state if
DS1232LP/LPS
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the strobe input is not driven low prior to time–out. The
watchdog timer function can be set to operate on time-
out settings of approximately 150 ms, 600 ms, and 1.2
seconds.
OPERATION – POWER MONITORThe DS1232LP/LPS detects out–of–tolerance power
supply conditions and warns a processor–based sys-
tem of impending power failure. When VCC falls below a
preset level as defined by TOL, the VCC comparator out-
puts the signals RST and RST. When TOL is connected
to ground, the RST and RST signals become active as
VCC falls below 4.75 volts. When TOL is connected to
VCC, the RST and RST signals become active as VCC
falls below 4.5 volts. The RST and RST are excellent
control signals for a microprocessor, as processing is
stopped at the last possible moments of valid VCC. On
power–up, RST and RST are kept active for a minimum
of 250 ms to allow the power supply and processor to
stabilize.
OPERATION – PUSHBUTTON RESETThe DS1232LP/LPS provides an input pin for direct con-
nection to a pushbutton (Figure 1). The pushbutton re-
set input requires an active low signal. Internally, this in-
put is debounced and timed such that RST and RST
signals of at least 250 ms minimum are generated. The
250 ms delay starts as the pushbutton reset input is re-
leased from low level.
OPERATION – WATCHDOG TIMERThe watchdog timer function forces RST and RST sig-
nals to the active state when the ST input is not stimu-
lated for a predetermined time period. The time period is
set by the TD input to be typically 150 ms with TD con-
nected to ground, 600 ms with TD left unconnected, and
1.2 seconds with TD connected to VCC. The watchdog
timer starts timing out from the set time period as soon
as RST and RST are inactive. If a high–to–low transition
occurs on the ST input pin prior to time–out, the watch-
dog timer is reset and begins to time–out again. If the
watchdog timer is allowed to time-out, then the RST and
RST signals are driven to the active state for 250 ms
minimum. The ST input can be derived from micropro-
cessor address signals, data signals, and/or control sig-
nals. When the microprocessor is functioning 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
shown in Table 1. A typical circuit example is shown in
Figure 2.
MICROMONITOR BLOCK DIAGRAMTOL
RST
PBRST
VCC
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PUSHBUTTON RESET Figure 1PBRST
+5 VDC
WATCHDOG TIMER Figure 2RST
PBRST
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TIMING DIAGRAM: PUSHBUTTON RESET Figure 3PBRST
RST
tRST
TIMING DIAGRAM: STROBE INPUT Figure 4RST
INDETERMINATE
STROBE
INVALID
STROBE
VALID
STROBE
WATCHDOG TIME–OUTS Table 1
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TIMING DIAGRAM: POWER DOWN Figure 5VCC
RST
RST
TIMING DIAGRAM: POWER UP Figure 6VCC
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ABSOLUTE MAXIMUM RATINGS*Voltage on VCC Pin Relative to Ground–0.5V to +7.0V
Voltage on I/O Relative to Ground–0.5V to VCC + 0.5V
Operating Temperature0°C to 70°C
Operating Temperature (Industrial Version)–40°C to +85°C
Storage Temperature–55°C to +125°C
Soldering Temperature260°C for 10 secondsThis 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.
RECOMMENDED DC OPERATING CONDITIONS(0°C to 70°C)
DC ELECTRICAL CHARACTERISTICS(0°C to 70°C; VCC = 4.5 to 5.5V)
CAPACITANCE(tA = 25°C)
