iC-JJ
POWER MANAGEMENT IC
Rev A1, Page 15/17
WATCHDOG
If the watchdog is not activated within the stipulated period (500µs..800ms), a reset is triggered via NRES. The
watchdog counter restarts with each falling edge at TWD. Reset pulses from the microcontroller or V(VCC) or
V(VREF) not included in the specifications also reset the watchdog counter.
NRHD and HD activate external hardware in conjunction with the watchdog.
NRDH: CMOS input with a pull-up resistor to activate output HD.
HD: after 128 correct watchdog cycles and when pin NRHD = high, the open-drain transistor is activated (HD =
low). Via NRHD = low, a reset (NRES) or false operation of the watchdog, the output is switched to tristate and
can only become low again when 128 correct watchdog cycles have again occurred.
RESET
If V(VCC) or V(VREF) are not within specifications range or if the watchdog is operated incorrectly a reset is
triggered via the open-drain output NRES. The microcontroller can also trigger a reset externally, thus resetting
the watchdog and switching the indicator lamp on via NFL.
VFP REGULATOR
The VFP regulator provides the microcontroller with 12V programming supply voltage. When TFP= high, output
VFP is activated; otherwise this output is switched to tristate.
STANDBY
Via input ENA a sleep mode can be set; current consumption is reduced to a minimum of 30µA approximately.
K-Interface
The K-Interface uses two pins that can be connected with the serial interface of the microcontroller.
TXD is used to send data via the interface. If TXD is switched from high to low then K switches from V (VM) to
low. RXD switches to low if V(RXD) < V (VM)/2 (in Autarky mode RXD < 3V). If TXD is open then RXD will reflect
the external voltage at K.
TEMPERATURE MONITORING
The K interface, indicator lamp output and NAKS output are shut off in the event of excessive temperature. The
two driver outputs can be forcibly switched on with excessive temperature for a short period if they are the cause
of this excessive temperature. If the level falls below that of the shutdown temperature (hysteresis) the drivers
can be switched on again.
OSCILLATOR
The oscillator provides an internal frequency of ca. 125kHz for the switching converters, watchdog counter and
autarky control.
ICHAUS [ IC-HAUS GMBH ]
