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FEATURES
5V power-on reset
3.3V power-on reset
Internal power is drawn from higher of either
the 5VIN input or the 3.3VIN input
Excellent for systems designed to operate
with dual power supplies
Asserts resets during power transients
Pushbutton reset input for system override
Maintains reset for 350 ms after VCC returns
to an in-tolerance condition
Reduces need for discrete components
Precision temperature-compensated voltage
reference and voltage sensor
8-pin DIP, 8-pin SOIC, and 8-pin µ-SOP
available
CMOS output for low current operation on
the DS1834 and DS1834D
Operating temperature of -40°C to +85°C
PIN ASSIGNMENT
PIN DESCRIPTION
5VIN - 5V Power Supply Input
5VRST (*RST) - 5V Reset Output
5V TOL - Selects 5V Input Tolerance
GND - Ground
PBRST - Pushbutton Reset
3.3V TOL - Selects 3.3V Input Tolerance
3.3V RST (*RST) - 3.3V Reset Output
3.3VIN - 3.3V Power Supply Input
*DS1834D Active High Reset
DESCRIPTION
The DS1834 Dual EconoResets monitors three vital system conditions: 5-volt supply, 3.3-volt supply,
and an external ove rri de. Fi rst a pr eci sion t emperat u re r eferenc e and comp arato r ci rcuit monit or th e stat us
of the 5-volt supply and the 3.3-volt supply. When an out-of-tolerance condition is detected, an internal
power-fail signal is generated which forces the reset of the affected supply to an active state.
Lastly, the DS1834 supports an external reset via an internally debounced pushbutton input. When the
pushbutton is pulled low both resets will be asserted for approximately 350 ms after the pushbutton is
released.
DS1834/A/D
Dual EconoReset with Pushbutton
www.dalsemi.com
DS1834 8-Pin SOIC (150-mil)
1
2
3
4
8
7
6
5
5VIN
5V RST
5V TOL
GND
3.3VIN
3.3V RST
3.3V TOL
PBRST
DS1834 8-Pin
µ
-SOP (118-mil)
5V
IN
5V RST
(
*RST
)
5V TOL
GND
3.3VIN
3.3V RST (*RST)
3.3V TOL
PBRST
1
2
3
4
8
7
6
5
DS1834 8-Pin DIP (300-mil)
5VIN
5V RST
5V TOL
GND
3.3VIN
3.3V RST
3.3V TOL
PBRST
1
2
3
4
8
7
6
5
DS1834/A/D
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OPERATION
Power Monitor
The DS1834 provides the functions of detecting out-of-tolerance conditions on a 3.3-volt and 5-volt
power supply and warning a processor-based system of impending power failure. When an input is
detected as out of tolerance on either voltage input the RST for that supply will be forced active. When
that input returns to a valid state the RST will remain active for about 350 ms and then return to an
inactive state until the next input out-of-tolerance condition.
On power-up both resets are kept active for approximately 350 ms after the power supply inputs have
reached the sel ected tolerance. This allows the powe r supply and s ystem power to stabilize befor e RST is
released.
All internal operating current fo r the DS1834 will be drawn from the input with the hi ghest voltage level.
The outputs will draw current only from the controlling input (5V IN or 3.3V IN).
DS1834 BLOCK DIAGR AM Figure 1
DS1834A BLOCK DIAGRAM OUTPUT Figure 2
DS1834/A/D
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Tolerance Select
The DS1834 provides two TOL inputs for individual customization of the DS1834 to specific application
requirements. If the TOL for the 5-volt supply is tied to the 5-volt input a 10% tolerance is selected for
the 5 volt supply. If the TOL for the 3.3-volt supply is tied to the 3.3-volt input, a 20% tolerance is
selected for the 3.3-volt supply. If TOL inputs are tied to ground, the 5-volt input will be set at a 5%
tolerance and the 3.3-volt input would be set to a 10% tolerance.
Pushbutton Reset
The DS1834 provides a pushbutton switch for manual reset control. When at least one of the DS1834
resets are not in a reset cycle, a pushbutton reset can be generated by pulling the PBRST pin low for at
least 2 ms. When the pushbutton is held low, both resets are forced active and will remain active for about
350 ms after the pushbutton is released. The pushbutton input is pulled high through an internal
40 kΩ=pull-up resistor and debounced via internal circuitry. See Figure 3 for an application example and
Figure 4 for the timing diagram.
PUSHBUTTON RESET Figure 3
TIMING DI AGRAM: PUSHBUTTON RESET Figure 4
DS1834/A/D
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OUTPUT VALID CONDITIONS
All versions of the DS1834 can maintain valid outputs as long as one input remains above 1.2 volts.
However, the RST outputs on the DS1834 use a push-pull output structure which can maintain a valid
output below 1.2 volts. To sink current below 1.2 volts a resistor can be connected from RST to GND
(see Figure 5). This arrangement will maintain a valid value on the RST outputs even if all inputs are at 0
volts. During both power-up and power-down this arrangement will draw current when RST is in the high
state. A value of about 100 kΩ=should be adequate to maintain a valid condition.
The DS1834A requires pull-up resistors on the outputs to maintain a valid output. The value of the
resistors is not critical in most cases but must be set low enough to pull the output to a high state. A
common value used is 10 kΩs (see Figure 6 and Figure 7).
APPLICATION DIAGRAM:
RST VALID TO 0 VOLTS VCC ON THE DS1834 Figure 5
APPLICATION DIAGRAM: DS1834A NMOS OUTPUTS Figure 6
Note: If outputs are pulled-up to different voltages the outputs can not be connected to form a wired
"AND".
APPLICATION DIAGRAM: DS1834A WIRED "AND" OUTPUT Figure 7
DS1834/A/D
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TIMING DI AGRAM: POWER-DOWN Figure 8
TIMING DIAGRAM: POWER-UP Figure 9
DS1834/A/D
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ABSOLUTE MAXIMUM RA TINGS*
Voltage on VIN Pin Relative to Ground -0.5V to +7.0V
Voltage on RST (5V) Pin Relative to Ground -0.5V to +0.5VIN + 0.5V (DS1834 & DS1834D)
Voltage on RST (3.3V) Pin Relative to Ground -0.5V to +3.3VIN + 0.5V (DS1834 & DS1834D)
Voltage on PBRST & RST (DS1834A) Pin
Relative to Ground -0.5 to the greater of 0.5VIN + 0.5V or 3VIN + 0.5V
Operating Temperature -40°C to +85°C
Storage Temper ature -55°C to +125°C
Soldering Temperature 260°C for 10 seconds
* 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.
RECOMMENDED DC OPERA TING CONDITIONS (-40°C to +85°C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
5VIN (Supply Voltage) VIN 1.2 5.5 V 1
3VIN (Supply Voltage) VIN 1.2 5.5 V 1
PBRST Input High Level VIH 2
VIN(MAX)
-0.4
VIN(MAX)
+0.3
V
V
1
1, 3
PBRST Input Low Level VIL -0.3 0.5 V 1
DC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC=1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Output Voltage VOH VIN
-0.1V
V1
Input Leakage IIL -1.0 +1.0 µA4
Output Current @ 2.4V IOH 350 µA5
Output Current @ 0.4V IOL +10 mA 5
Operating Current @ Ο 5.5VIN ICC 50 µA6
Operating Current @ Ο 3.6VIN ICC 35 µA7
5VIN Trip Point (TOL=GND) VINTP 4.50 4.63 4.75 V 1
5VIN Trip Point (TOL=5VIN)V
INTP 4.25 4.38 4.49 V 1
3.3VIN Trip Point (TOL=GND) VINTP 2.80 2.88 2.97 V 1
3.3VIN Trip Point (TOL=3.3VIN)V
INTP 2.47 2.55 2.64 V 1
Output Capacitance COUT 10 pF
DS1834/A/D
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AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC=1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
PBRST = VIL tPB 2ms
PBRST Stable Low to Reset
Active tPDLY 2ms
Reset Active Time tRST 200 350 500 ms
VCC Detect to RST (or RST) tRPD 2µs8
VCC Slew Rate (VINTP(MAX) to
VINTP(MIN))tF300 µs
VCC Slew Rate (VINTP(MIN) to
VINTP(MAX))tR0ns
VCC Detect to RST (or RST) tRPU 200 350 500 ms 9
NOTES:
1. All voltages are referenced to ground.
2. Measured with both 3.3VIN and 5VIN =2.7V.
3. Measured with both 3.3VIN and 5VIN =2.7V.
4. PBRST is internally pulled up to VIN(MAX) input with an internal impedance of approximately 40 kΩ.
5. Measured with either 3.3VIN or 5VIN =2.7V (valid for DS1834 and DS1834D only).
6. Measured with outputs open and both 3.3VIN and 5VIN =5.5V.
7. Measured with outputs open and both 3.3VIN and 5VIN =3.6V.
8. Noise immunity - pulses < 2 µs @ VCCTP minimum will not generate a reset.
9. tR =5 µs.
MARKING: DS1834 DS1834A DS1834D
8-pin DIP DS1834 DS1834A DS1834D
8-pin SOIC DS1834 DS1834A DS1834D
8-pin -SOP 834 834A 834D
