Circuit Description
5-10
SF700AT
POWER MONITOR
If 5V power to KIA7045F drops to between 4.65
and 4.35V (typically 4.5V), power failure will be
indicated and the output of KIA7045F will go 'low'
(GND). This causes the IFC to become active
('low'=reset). The IFC reset causes the MODEM
IFC/RESET terminal to be reset. The output
terminal of KIA7045F is an open-drain
configuration, and is connected to PFC through a
10k pull-up resistor.
WATCH DOG TIMER
This programmable counter in the IFC is reset
every 2 ms. If not reset after 250 ms, the system is
automatically reset and switches to initialise mode.
BATTERY POWER RESET
When battery power (V
B
) is applied to IFC the first
time, V
B
current results in /BATRST going 'low',
causing a reset to occur.
5-2-14 Reset
Two power resets and a watchdog timer in the IFC
comprise the elements of this circuit. Battery
power reset (/BATRST) is used to initialise the
battery-powered logic, and primary power reset
(/PWRDWN) initialises non-battery-powered
logic when system power is supplied.
Figure 5-12: Power Reset Block Diagram
icik (TSTCLK)
Watchdog Reset
Reset clock
reset
Divider
XOUT
/PWRDWN
Power
Down
NMI
Power up Delay 1
(1-2 Reset clocks)
Power up Delay 2
(8 TSTCLKS)
vddresn
RESETn
resn
To internal logic
Clock enable
MC24 NMI
routine
set
lock
clear
Lockout
Logic
lockout
to battery (BackupConfig) register reset
BATRSTn
set tristate
Tristate
Control
CS0n
Содержание SF700AT
Страница 2: ...Samsung Electronics Co Ltd APR 1998 Printed in Korea JF68 60A ELECTRONICS ...
Страница 34: ...Circuit Description 5 16 SF700AT MEMO ...
Страница 52: ...8 1 SF700AT 8 Exploded Views and Parts Lists 8 1 Total Assembly ...
Страница 54: ...SF700AT 8 3 Exploded Views and Parts Lists 8 2 Ass y OPE Unit ...
Страница 56: ...Exploded Views and Parts Lists SF700AT 8 5 8 3 Ass y RX COVER ...
Страница 61: ...Exploded Views and Parts Lists 8 10 SF700AT 8 7 Ass y Base ...
Страница 63: ...Exploded Views and Parts Lists 8 12 SF700AT 8 8 Harness ...