|
|
Power
Management In The ST62
Design Idea published in the
Electronic Engineering magazine on March 1996.
|
|
|
DESIGN IDEAS - CMOS IC Makes Low-Cost Digital Potentiometer - Power Management In The ST62 - Automatic Power-Off Circuit Saves Battery - Simple PC Smart Card Reader Enhancement - Digital Position Encoder Does Away With ADC - Single-Supply RS-232 Transmission Without Level-Translator ICs - µC Controls Charge Pump As Background Task - Clock Multiplier Circumvents PLL - Drive Smart Cards With A Low-Cost MCU's UART - Wireless “Battery” Energizes Low-Power Devices - Harvest Energy Using A Piezoelectric Buzzer - Drive A Single-Coil Latching Relay Without An H-Bridge Circuit DESIGN CONTESTS ARTICLES
CONTACT
|
Designers
of hand-held devices have special requirements of power consumption, so
they must use low power ICs and microcontrollers with low-power modes
such as wait, stop, idle or sleep modes for power management. The
ST62xx MCU family from SGS Thomson is a low-cost, low-power with a small
footprint and an easy to use instruction set MCU. But in the hardware
watchdog version of the chip it is very difficult to use the low power
modes because the on-chip watchdog is always enabled by hardware, so if
you enter the wait mode the watchdog may cause an unwanted reset if you
do not refresh the watchdog register on time. However, you can disable
the watchdog externally by connecting a pull-up resistor valued lower
than 30K Ohms
between Vdd and the reset pin (Figure 1), so the reset request generated
by the on-chip watchdog is unable to pull-down the reset pin resulting
in an external deactivation of the watchdog function.
|
|
