DS1831C/D/E 3.3V/2.5V Multi-Supply MicroMonitor www.dalsemi.com FEATURES PIN ASSIGNMENT 2.5V power-on reset 3.3 (or 3V) power-on reset 2 referenced comparators with separate outputs for monitoring additional supplies Internal power is drawn from higher of either the IN2.5V input or the IN3.3V input Excellent for systems designed to operate with multiple power supplies Asserts resets during power transients Pushbutton reset input for system override Maintains reset for user configurable times of 10 ms, 100 ms, or 1 sec Watchdog timer for software monitoring (DS1831D) Precision temperature-compensated voltage reference and voltage sensor 16 pin DIP & 16 pin 150 mil SOIC available Operating Temperature of -40°C to +85°C DS1831C IN2.5V 1 16 IN3.3V RST2.5V 2 15 RST3.3V TOL2.5V 3 14 TOL3.3V TD2.5V 4 13 TD3.3V PBRST2.5V 5 12 PBRST3.3V IN1 6 11 NMI1 IN2 7 10 NMI2 GND 8 9 MPBRST 16-Pin (300 mil) DIP & 16-Pin (150 mil) SOIC DS1831D IN1 6 11 NMI1 ST 7 10 WDS GND 8 9 TDWD DS1831E TD2.5V 4 13 TD3.3V PBRST2.5V 5 12 PBST IN1 6 11 NMI1 DESCRIPTION The DS1831C Multi-Supply Monitor & Reset monitors up to 4 system voltages: 2.5 volt supply, 3.3 (or 3) volt supply, and 2 additional user configurable voltage monitors. DS1831 power for internal operation comes from the higher voltage level of the 3.3 volt input or the 2.5 volt input. One of these inputs must be greater than 1 volt for device operation. Pushbutton (manual reset) functionality is provided for the 2.5 volt reset, the 3.3 volt reset or for all reset outputs by the master pushbutton. The DS1831D replaces one reference comparator and the master pushbutton with watchdog and the DS1831E replaces the 3.3-volt PBRST with a last reset status output. TOL and TD inputs allow user configuration of the DS1831 for multiple applications. The TOL inputs configure the tolerance for the specified output and the TD inputs configure the reset time delays. 1 of 14 051100 DS1831C/D/E PIN CONFIGURATION 1 IN2.5V 2.5V Power Supply Input 2 RST 2.5V 2.5V Reset Open Drain Output 10 Selects 2.5V Input Tolerance Selects 2.5V Reset Time Delay PBRST 2.5V 2.5V Reset Pushbutton IN1 IN2 ST Sense Input 1 Sense Input 2 (DS1831C/E) Watchdog Strobe Inputs (DS1831D) Ground 3 TOL2.5V 4 TD2.5V 5 6 7 8 GND 9 WDS Master Pushbutton (DS1831C/E) Watchdog Time Delay Select (DS1831D) Non Maskable Interrupt 2 (DS1831C/E) Watchdog Status Output (DS1831D) 11 NM11 Non Maskable Interrupt 1 12 PBRST 3.3V 13 TD3.3V 3.3V Reset Pushbutton (DS1831C/E) Pushbutton Status Output (DS1831E) Select 3.3V Reset Time Delay 14 TOL3.3V 15 RST 3.3V Selects 3.3V Input Tolerance 3.3V Reset Open Drain Output 16 IN3.3V 3.3V Power Supply Input MPBRST TDWD NM12 PBST BLOCK DIAGRAM Figure 1 IN2.5V 100 kΩ PBRST2.5V TD2.5V VCC TOL2.5V TOLERANCE BIAS + TIME DELAY 1.25V T.C. REFERENCE - 100 kΩ MPBRS RST2.5V Level Sense & Debounce IN3.3V 100 kΩ PBRST3.3V TD3.3V TOL3.3V VCC TOLERANCE BIAS TIME DELAY + RST3 3V - IN NMI + - IN NMI + GROUN 2 of 14 DS1831C/D/E OPERATION – POWER MONITOR The DS1831 provides the functions of detecting out-of-tolerance conditions on a 3.3 (or 3) volt and 2.5 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 low. When that input returns to a valid state the associated RST will remain active for the time delay selected with the associated TD input and then return to an inactive state until the next input out-of-tolerance condition. On power-up both resets are kept active for the selected reset time after the associated power supply input has reached the selected tolerance. This allows the power supply and system power to stabilize before RST is released. All internal operating current for the DS1831 will be supplied by either the IN3.3V or IN2.5V input which ever has the highest voltage level. OPERATION - TOLERANCE SELECT The DS1831 provides 2 TOL inputs for individual customization of the DS1831 to specific application requirements. If the TOL for the 2.5 volt supply is tied to the 2.5 volt input a 5% tolerance is selected. If the TOL is connected to ground a 10% tolerance is selected or if it is left unconnected a 15% tolerance is selected. If the TOL for the 3.3 volt supply is tied to the 3.3 volt input a 5% tolerance is selected, a 10% tolerance is selected if it is connected to ground, and a 20% tolerance is selected if the input is left unconnected. These tolerance conditions are set at power up and can only be changed by power cycling the device. OPERATION - RESET TIME-DELAY SELECT The DS1831 provides 2 TD inputs for individual customization of reset time delays and an additional one for the DS1831D watchdog. TD inputs select time delays for the IN2.5V and IN3.3V resets outputs and the Watchdog on the DS1831D. The reset time delays are shown in table 1. These allow the selection of minimum delays of 10 ms, 100 ms, and 1000 ms. Wiring an individual reset output to the push-button input of the other voltage reset allows custom reset timings or allows for the sequencing of the reset outputs. See figure 2. These time delays are set at power-up and cannot be changed after the device reaches an in-tolerance condition. TD INPUTS/RESET AND WATCHDOG TIME-DELAYS Table 1 TD GND Float VCC MIN 10 ms 100 ms 1000 ms RESET TIME-DELAY TYP 16 ms 160 ms 1600 ms 3 of 14 MAX 20 ms 200 ms 2000 ms DS1831C/D/E PUSHBUTTON RESET SEQUENCING Figure 2 3.3V Supply 2.5V Supply IN2.5V * RST2.5V TOL2.5V TD2.5V PBRST2.5V 16 1 2 15 DS1831C 14 3 4 13 5 12 IN3.3V RST3.3V TOL3.3V TD3.3V PBRST3.3V GND *NOTE: The RST 2.5 volt output is connected to the IN3.3V via a 100 kΩ resistor in the push-button input and therefore does not require a pull-up resistor (an addition pull up can be used to accelerate responses.) If an external pull-up is used in this example it must be connected to the 3.3 volt power supply. OPERATION - PUSHBUTTON RESET The DS1831 provides 3 pushbutton inputs for manual reset of the device. Pushbutton inputs for the 3.3 volt reset, 2.5 volt reset, and a master pushbutton reset (DS1831C & DS1831D only) input; provide multiple options for system control. The 3.3 volt pushbutton reset and 2.5 volt pushbutton resets provide a simple manual reset for the associated reset output; while the master pushbutton reset forces all resets and NMI outputs active low. The 2.5 volt reset pushbutton input and the 3.3 volt reset pushbutton input provide manual reset control for each associated reset output. When the output associated with a pushbutton input is not active, a pushbutton reset can be generated by pulling the associated PBRST pin low for at least 20 µs. When the pushbutton is held low the reset will be forced active and will remain active for a reset cycle after the pushbutton is released. See figure 2 for an application example that allows a user to sequence the reset outputs. A master pushbutton reset cycle can be started if at least one voltage input (IN2.5V, IN3.3V, IN1, or IN2) is in tolerance and at least 1 output is active. A master pushbutton reset is generated by pulling the MPBRST pin low for at least 20 µs. When the pushbutton is held low all outputs are forced active and will remain active for a reset or NMI time delay after the pushbutton is released. The Master Pushbutton input is pulled high through an internal 100 kΩ pull up resistor and debounced via internal circuitry. See figure 3 for an application example. Figures 4 and 5 for the timing diagram. The 2.5 volt and 3.3 volt pushbutton reset inputs are pulled high through an internal 100 kΩ pull up resistor to the voltage input, which is associated with that pushbutton. The master pushbutton is pulled to the greater of the “IN2.5V” and “IN3.3V” inputs. *Caution should be exercised to avoid pulling the pushbutton inputs above associated supply inputs. Generally all pushbutton inputs should be driven low with open drain inputs. 4 of 14 DS1831C/D/E PUSHBUTTON RESET Figure 3 2.5V Supply IN2.5V 10 kΩ 1 16 2 DS1831C 15 3 14 4 13 5 12 RST2.5V TOL2.5V TD2.5V PBRST2.5V GND TIMING DIAGRAM – MASTER PUSHBUTTON RESET Figure 4 tPB MPBRST tPDLY VIH VIL tRST RST2.5V and RST3.3V VOH NMI1 and NMI2 tNMI VOH TIMING DIAGRAM – 2.5V OR 3.3V PUSHBUTTON RESET Figure 5 tPB PBRST2.5V (or PBRST3.3V) tPDLY VIH VIL tRST RST2.5V (or RST3.3V) VOH VIL 5 of 14 DS1831C/D/E OPERATION – PUSHBUTTON STATUS The DS1831E provides a master pushbutton status open drain output. The PBST output indicates the status of the most recent reset condition. If the last reset was generated by the master pushbutton input it would maintain a low condition until cleared by another event (except the master pushbutton) generating a reset. Once cleared it will remain high until the master pushbutton is pulled low generating a reset condition. The PBST output is open drain and will require a pull-up resistor on the output to maintain a valid condition. The value of the pull up resistor 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). DS1831E APPLICATION EXAMPLE Figure 6 2.5V 3.3V Supply IN2.5V RST2.5V VSENSE2 VSENSE1 1 16 IN3.3V 15 TOL2.5V 3 14 TOL3.3V TD2.5V 4 13 TD3.3V IN1 IN2 GND DS1831E 5 12 6 11 7 10 8 9 10k RST3.3V 2 PBRST2.5V VCC VCC 10 kΩ PBST NMI1 NMI2 MPBRST OUTPUT VALID CONDITIONS The DS1831 can maintain valid outputs as long as one input remains above 1.0 volt. Accurate voltage monitoring additionally requires that either the 3.3 volt IN or 2.5 volt IN input be above 1.5 volts. If this condition is not met and at least one of the supply inputs are at or above 1.0 volt all outputs are maintained in the active condition. The DS1831 requires pull-up resistors on the outputs to maintain a valid output. The value of the pull up resistor is not critical in most cases but must be set low enough to pull the output to a high state. A common pull-up resistor value used is 10 kΩs (See Figure 7). 6 of 14 DS1831C/D/E APPLICATION DIAGRAM - OPEN DRAIN OUTPUTS Figure 7 3.3V Supply 2.5V Supply IN2.5V 10 KΩ RST2.5V TOL2.5V TD2.5V PBRST2.5V 1 16 2 15 DS1831C 3 14 4 13 5 12 IN3.3v 10 KΩ RST3.3V TOL3.3V TD3.3V PBRST3.3V GND NOTE: If outputs are at different voltages the outputs can not be connected to form a wired AND. OPERATION - NON-MASKABLE INTERRUPT The DS1831 has 2 referenced comparator (DS1831D has only 1 referenced comparator) that can be used to monitor upstream voltages or other system specific voltages. Each comparator is referenced to the 1.25 volt internal band gap reference and controls an open drain output. When a voltage being monitored decays to the voltage sense point, the DS1831 pulses the NMI output to the active state for a minimum 10 µs. The comparator detection circuitry also has built-in hysteresis of 100 µV. The supply must be below the voltage sense point for approximately 2 µs before a low NMI will be generated. In this way, power supply noise is minimized in the monitoring function, reducing false interrupts. See Figure 8 for the non-maskable timing diagram. Versatile trip voltages can be configured by the use of an external resistor divider to divide the voltage at a sense point to the 1.25 volt trip levels of the referenced comparators. See figure 9 for an example circuit diagram and sample equations. The equations demonstrate a design process to determine the resistor values to use. Connecting one or both NMI outputs to one of the reset specific PBRST ’s allows the non-maskable interrupt to generate an automatic reset for the reset time period when an out-of-tolerance condition occurs in a monitored supply. An example is shown in Figure 9. The output associated with the specific input will be held low if the voltage on the input pin is less than 1.25 volts. If the voltage is above 1.25 volts the output will not sink current and will be pulled up by the required pull up resistor. 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. If a NMI output is connected to a pushbutton input an additional pull-up resistor can be used (to improve speed of transitions) but is not required. During a power-up, any detected IN pin levels above VTP by the comparator are disabled from generating an inactive (high) interrupt until at least 1 supply on the VIN inputs rises above 1.5 volts. All NMI outputs will be held active (low) until at least one VIN reaches 1.5 volts at which point the NMI outputs will be based on the value of the associated IN input. 7 of 14 DS1831C/D/E TIMING DIAGRAM - NON MASKABLE INTERRUPT Figure 8 VIN >1.25 V VTP(max) VTP VTP(min) VTP VTP(min) VTP(max) tNMI NMI tIPD VOH VOL NON MASKABLE INTERRUPT CIRCUIT EXAMPLE Figure 9 VSENSE1 VSENSE2 VCC R1 PBRST3.3V PBRST2.5V IN1 R3 R2 NMI1 IN2 R4 10 kΩ DS1831C NMI2 GND MPBRST Example: VSENSE1 = 11.50 volts trip point Therefore: 11.50V = R1 + 100 kΩ 100 kΩ VSENSE1 = X 1.25V Resulting In: R1 = 820 kΩ Repeat the same steps to solve for R3 and R4 with VSENSE2. 8 of 14 R1 + R2 R2 X 1.25V DS1831C/D/E OPERATION - WATCHDOG TIMER The watchdog timer function (DS1831D only) forces the WDS signal active (low) when the ST input does not have a transition (high-to-low or low-to-high) within the predetermined time period. The time-out period is determined by the condition of the TDWD pin. If TDWD is connected to ground the minimum watchdog time-out would be 10 ms, TD floating would yield a minimum time-out of 100 ms, and TDWD connected to VCC would provide a time-out of 1000 ms minimum. Time-out of the watchdog starts when at least one of the RST outputs becomes inactive (high). If a 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, then the WDS output is pulsed active for a minimum of 100 µs. The WDS output is an open-drain output and must be pulled up externally. In most applications this output would be connected to one of the Pushbutton inputs and would not require an external pull-up resistor. 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. If a WDS output is connected to a pushbutton input an additional pull-up resistor can be used (to improve speed of transitions) but is not required. The ST input can be derived from many microprocessor outputs. The most typical signals used are the microprocessor 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 transition must occur at or less than the minimum times shown in Table 1. A typical circuit example is shown in Figure 10. The watchdog timing is shown in Figure 11. The DS1831A watchdog function cannot be disabled. The watchdog strobe input must be strobed to avoid a watchdog time-out however the watchdog status output can be disconnected yielding the same result. WATCHDOG CIRCUIT EXAMPLE Figure 10 VSENSE1 VCC R1 PBRST3.3V PBRST2.5V IN1 µP R2 NMI1 10 kΩ DS1831D ST WDS GND TDWD 9 of 14 DS1831C/D/E TIMING DIAGRAM-STROBE INPUT Figure 11 INVALID EDGES VALID EDGES INDETERMINATE EDGES ST MIN. tST MAX. tTD WDS RESET TIMING DIAGRAM - POWER UP Figure 12 tR VINTP (MAX) VINTP (MIN) VINTP IN2.5V (or IN3.3V) tRPU VOH RST2.5V (or RST3.3V) 10 of 14 DS1831C/D/E RESET TIMING DIAGRAM - POWER DOWN Figure 13 tF IN2.5V (or IN3.3V) VINTP (MAX) VINTP RST2.5V (or RST3.3V) VINTP (MIN) tRPD VOL 11 of 14 DS1831C/D/E ABSOLUTE MAXIMUM RATINGS* Voltage on IN2.5V or IN3.3V Pins Relative to Ground Voltage on either RST Relative to Ground Voltage on PBRST3.3V Relative to Ground Voltage on PBRST2.5V Relative to Ground Voltage on MPBRST Relative to Ground Operating Temperature Storage Temperature Soldering Temperature -0.5V to +7.0V -0.5V to the greater of IN2.5V + 0.5V or IN3.3V + 0.5V -0.5V to IN3.3V + 0.5V -0.5V to IN2.5V + 0.5V -0.5V to the greater of IN2.5V + 0.5V or IN3.3V + 0.5V -40°C to +85°C -55°C to +125°C See J-STD-020A specification * 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 and ST inputs can be exceeded if the input current is less than 10 mA. RECOMMENDED DC OPERATING CONDITIONS PARAMETER SYMBOL MIN IN2.5V (Supply Voltage) V IN 1.0 IN3.3V (Supply Voltage) V IN 1.0 2 ST and MPBRST input VIH VINT-0.4 High Level VIH 2 PBRST 3.3V input High Level VIH 2 PBRST 2.5V input High Level ST, PBRST 3.3V, PBRST 2.5V and VIL -0.3 MPBRST input Low Level * VINT is the greater voltage level of the IN2.5V or IN3.3V. DC ELECTRICAL CHARACTERISTICS PARAMETER Input Leakage Output Current @ 2.4V Output Current @ 0.4V Operating Current @ ⇐5.5V Operating Current @ ⇐3.6V IN3.3V Trip Point (TOL3.3V = IN3.3V) IN3.3V Trip Point (TOL3.3V = GND) IN3.3V Trip Point (TOL3.3V = Float) IN2.5V Trip Point (TOL2.5V = IN2.5V) IN2.5V Trip Point (TOL2.5V = GND) IN2.5V Trip Point (TOL2.5V = Float) IN Input Trip Points (-40° to 85°C) MAX 5.5 5.5 IN3.3V + 0.3 IN2.5V +0.3 UNITS V V V V V V NOTES 1 1 1,2* 1,3* 1 1 .5 V 1 VINT + 0.3 (-40° to 85°C, VCC = 1.0V TO 5.5V) SYMBOL IIL IOH IOL ICC ICC VINTP VINTP VINTP MIN -1.0 TYP MAX +1.0 UNITS µA 2.98 2.80 2.47 80 60 3.06 2.88 2.55 100 80 3.15 2.97 2.64 mA µA µA V V V NOTES 4 5 6 7 8 1 1 1 VINTP 2.250 2.312 2.375 V 1 VINTP VINTP VTP 2.125 2.000 1.20 2.187 2.062 1.25 2.250 2.125 1.30 V V V 1 1 1 +10 12 of 14 DS1831C/D/E CAPACITANCE PARAMETER Input Capacitance Input Capacitance (tA = 25°C) SYMBOL CIN COUT MAX 5 7 AC ELECTRICAL CHARACTERISTICS PARAMETER RESET Active Time (TD=Low) RESET Active Time (TD=Float) RESET Active Time (TD=High) VCC Detect to RST VCC Detect to RST VIN Detect to NMI NMI Active Time PBRST = VIL PBRST Stable Low to Reset Active Watchdog Timeout (TD(WD)=Low) Watchdog Timeout (TDWD=Float) Watchdog Timeout (TDWD=High) ST Pulse Width Vin Slew Rate (V INTP(MAX) to V INTP(MIN)) Vin Slew Rate (V INTP(MAX) to V INTP(MIN)) SYMBOL tRST tRST tRST tRPU tRPD tIPD tNMI tPB UNITS pF pF NOTES (-40° to 85°C, VCC = 1.0V TO 5.5V) MIN TYP MAX 10 16 20 100 160 200 1000 1600 2000 See RESET Active Time 2 10 2 10 20 20 tPDLY 16 160 1600 UNITS ms ms ms ms µs µs µs µs 50 µs 20 200 2000 ms ms ms ns tTD tTD tTD tST 10 100 1000 10 tF 300 µs tR 0 ns NOTES 8 8 8 8 9 9 NOTES: 1. 2. 3. 4. 5. 6. 7. 8. 9. All voltages are referenced to ground. Measured with both IN3.3V & IN2.5V ≥ 2.7V. Measured with both IN3.3V & IN2.5V ≤ 2.7V. All Pushbutton inputs are internally pulled to the associated Supply IN input or the greatest Supply IN input for the MPBRST with an internal Impedance of 100 kΩ. All outputs are Open Drain and output IOH would be determined by the external pull-up resistor. Measured with outputs open and IN3.3V or IN2.5V ≤ 5.5V. Measured with outputs open and IN3.3V or IN2.5V ≤ 3.6V. Measured using tR = 5 µs. Noise immunity - pulses <2 µs at a trip level will not cause a RST or NMI . 13 of 14 DS1831C/D/E Ordering Information Ordering Part Package Type Description Number DS1831C 16 Pin DIP 300 mil 2.5V/3.3V MultiSupply Monitor DS1831CS 16 Pin SO 150 mil 2.5V/3.3V MultiSupply Monitor DS1831D 16 Pin DIP 300 mil 2.5V/3.3V MultiSupply Monitor w/Watchdog DS1831DS 16 Pin SO 150 mil 2.5V/3.3V MultiSupply Monitor w/Watchdog DS1831E 16 Pin DIP 300 mil 2.5V/3.3V MultiSupply Monitor w/Pushbutton Status DS1831ES 16 Pin SO 150 mil 2.5V/3.3V MultiSupply Monitor w/Pushbutton Status * Add “/T&R” for tape and reeling of surface mount packages. 14 of 14