CS8140

Features:

·5V ± 4%, 500mA Output Voltage
·µP Compatible Control Functions Watchdog RESET ENABLE
·Low Dropout Voltage (1.25V @ 500mA)
·Low Quiescent Current (7mA @ 500mA)
·Low Noise, Low Drift
·Low Current SLEEP Mode (IQ = 250µA)
·Fault Protection Thermal Shutdown Short Circuit 60V Peak Transient Voltage


Pinout




Specifications

Input Voltage
Operating Range...................................................................................................-0.5 to +26V
              Peak Transient Voltage (46V Load Dump @ 14V VBAT) .........................................60V
              Electrostatic Discharge
              (Human Body Model)..............................................................................................4kV
WDI Input Signal Range ..........................................................................................-0.3 to +7V
Internal Power Dissipation ..............................................................................Internally limited
Junction Temperature Range (TJ) ......................................................................-40 to +150
Storage Temperature Range..............................................................................-65 to +150
Lead Temperature Soldering
              Wave Solder (through hole styles only) .................................10 sec. max, 260 peak
              Reflow (SMD styles only) ....................................60 sec. max above 183, 230 peak
ENABLE ......................................................................................................................-0.3V to V_IN


Description

The CS8140 is a 5V Watchdog Regulator with protection circuitry and three logic control functions that allow a microprocessor to control its own power supply. The CS8140 is designed for use in automotive, switch mode power supply post regulator, and bat- tery powered   systems.

CS8140 Basic regulator performance character- istics include a low noise, low drift, 5V ± 4% precision output voltage with low dropout voltage (1.25V @ IOUT = 500mA) and low quiescent current (7mA @ IOUT = 500mA). On board short circuit, ther- mal, and overvoltage protection make it possible to use this regulator in particu- larly harsh operating environments.

The Watchdog logic function monitors CS8140 an input signal (WDI) from the micro- processor or other signal source. When the signal frequency moves outside externally programmable window lim- its, a RESET signal is generated (RESET). An external capacitor (CDELAY) programs the watchdog win- dow frequency limits as well as the power on reset (POR) and RESET delay.

The RESET function CS8140 is activated by any of three conditions: the watchdog sig- nal moves outside of its preset limits; the output voltage drops out of regula- tion by more than 4.5%; or the IC is in its power up sequence. The RESET sig- nal is independent of VIN and reliable down to V_OUT = 1V.

In conjunction with the Watchdog, the ENABLE function controls the regula- tor's power consumption. The CS8140's output stage and its attendant circuitry are enabled by setting the ENABLE lead high. The regulator goes into sleep mode (IOUT = 250µA) when the ENABLE lead goes low and the watch- dog signal moves outside its preset window limits. This unique combina- tion of control functions in the CS8140 gives the microprocessor control over its own power down sequence: i.e. it gives the microprocessor the flexibility to perform housekeeping functions before it powers down.

The CS8141 has the same features as the CS8140, except that the CS8141 only responds to input signals (WDI) which are below the preset watchdog frequen- cy threshold.