Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - system monitor Reset/power-on reset SOIC 8

1 of 7 112099

FEATURES

 Halts and restarts an out-of-control

microprocessor

 Holds microprocessor in check during power

transients

 Automatically restarts microprocessor after

power failure

 Monitors pushbutton for external override

 Accurate 10% or 20% microprocessor power

monitoring

 Eliminates need for discrete components

 20% tolerance for use with 3.0-volt systems

 Pin-compatible with the DS1232

 Low cost 8-pin DIP, 8-pin SOIC, and space

saving µ-SOP packages available

 Industrial temperature range of -40°C to

+85°C

PIN ASSIGNMENT

PIN DESCRIPTION

PBRST - Pushbutton Reset Input

TD - Time Delay Set

TOL - Selects 10% or 20% V

Detect

GND - Ground

RST - Active High Reset Output

RST - Active Low Reset Output

ST - Strobe Input

- Power Supply

DESCRIPTION

The DS1832 3.3-Volt MicroMonitor monitors three vital conditions for a microprocessor: power supply,

software execution, and external override. First, a precision temperature-compensated reference and

comparator circuit monitor the status of V

. When an out-of-tolerance condition occurs, an internal

power-fail signal is generated which forces the resets to an active state. When V

returns to an

in-tolerance condition, the reset signals are kept in the active state for a minimum of 250 ms to allow the

power supply and processor to stabilize.

DS1832

3.3-Volt MicroMonitor Chip

www.dalsemi.com

DS1832 8-Pin DIP (300-mil)

See Mech. Drawings Section

PBRST

TOL

GND

RST

DS1832S 8-Pin SOIC (150-mil)

See Mech. Drawings Section

PBRST

TOL

GND

RST

DS1832

8-Pin

-SOP (118-mil)

See Mech. Drawings Section

PBRST

TOL

GND

RST

Summary of content (7 pages)

PAGE 1
DS1832 3.3-Volt MicroMonitor Chip www.dalsemi.com FEATURES PIN ASSIGNMENT Halts and restarts an out-of-control microprocessor Holds microprocessor in check during power transients Automatically restarts microprocessor after power failure Monitors pushbutton for external override Accurate 10% or 20% microprocessor power monitoring Eliminates need for discrete components 20% tolerance for use with 3.
PAGE 2
DS1832 The second function the DS1832 performs is pushbutton reset control. The DS1832 debounces the pushbutton input and guarantees an active reset pulse width of 250 ms minimum. The third function is a watchdog timer. The DS1832 has an internal timer that forces the reset signals to the active state if the strobe input is not driven low prior to timeout. The watchdog timer function can be set to operate on timeout settings of approximately 150 ms, 600 ms, or 1.2 seconds.
PAGE 3
DS1832 MICROMONITOR BLOCK DIAGRAM Figure 1 PUSHBUTTON RESET Figure 2 TIMING DIAGRAM: PUSHBUTTON RESET Figure 3 3 of 7
PAGE 4
DS1832 WATCHDOG TIMER Figure 4 WATCHDOG TIMEOUTS Table 1 TIMEOUT TD GND MIN 62.
PAGE 5
DS1832 TIMING DIAGRAM: POWER-UP Figure 7 RST VALID TO 0 VOLTS VCC Figure 8 OUTPUT VALID CONDITIONS The RST output uses a push-pull output which can maintain a valid output down to 0.8 volts VCC. To sink current below 0.8 volts a resistor can be connected from RST to Ground (see Figure 8). This arrangement will maintain a valid value on RST during both power-up and power-down but will draw current when RST is in the high state. A value of about 100 kΩ=should be adequate in most situations.
PAGE 6
DS1832 ABSOLUTE MAXIMUM RATINGS* Voltage on any Pin Relative to Ground Voltage on I/O Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * -0.5V to +7.0V -0.5V to VCC +0.5V -40°C to +85°C -55°C to +125°C 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.
PAGE 7
DS1832 AC ELECTRICAL CHARACTERISTICS PARAMETER (-40°C to +85°C; VCC=1.2V to 5.5V) MIN 20 TYP MAX = VIL SYMBOL tPB UNITS ms RESET Active Time tRST 250 610 1000 ms Pulse Width tST 20 PBRST ST VCC Detect to RST and RST VCC Slew Rate VCC Detect to RST and RST VCC Slew Rate PBRST Stable Low to RST and RST tRPD 5 tF 20 tRPU 250 tR 0 8 610 1000 20 1. All voltages referenced to ground. 2. PBRST is internally pulled up to VCC with an internal impedance of 40 kΩ=typical. 3.