M37517F8HP Datasheet, PDF (43/98 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

7517 Group
Over current detector
Over current detector detects the over current which flows through
the sense resistor connected between ISENS1 pin and ISENS0
pin, and turn off the discharge control FET to stop battery from dis-
charging. In the low power state, and when current integrator
disables, wake up current detector which detects approximate 1
mA current and generates the interrupt is also built-in.
Short current detector
Short current detector detects the short current (10A-47.5A) with
10 mΩ sense resistor. Setting short current detect enable bit of the
short current detect control register (000F16) “1”, short current de-
tector starts the operation. The compare voltage is determined by
setting the short current detect voltage select bit of the short cur-
rent detect control register, and the detect time is determined by
setting the short current detect time set up bit of the current detect
time set up register (001116).
The potential difference between sense resistor exceeds the com-
pare voltage and continue more than detect time, then short
current detect flag (bit 2 of 001316) becomes “1”, and short current
detect interrupt occurs.
Enabling interrupt for short current detect is determined by short
current interrupt enable bit. And in case of the FET control enable
bit is “1”, The FET control signal is generated from DFETCNT pin
with short current interrupt. The polarity of the FET control signal
is determined by setting the FET control polarity switch bit (bit 5 of
000F16).
Setting the short current detect restart bit(bit 6 of 001316) “1”
makes the short current detect state clear.
Over current detector
Over current detector detects the over current (5A-20.5A) with 10
mΩ sense resistor. Setting over current detect enable bit of the
over current detect control register (001016) “1”, over current de-
tector starts the operation. The compare voltage is determined by
setting the over current detect voltage select bit of the over current
detect control register (001016), and the detect time is determined
by setting the over current detect time set up bit of the current de-
tect time set up register (001016)
The potential difference between sense resistor exceeds the com-
pare voltage and continue more than detect time, then over
current detect flag (bit 1 of 001316) becomes “1”, and over current
detect interrupt occurs.
Enabling interrupt for over current detect is determined by over
current interrupt enable bit. And in case of the FET control enable
bit is “1”, the FET control signal is generated from DFETCNT pin
with over current interrupt.
Setting the over current detect restart bit (bit 5 of 001316) “1”
makes the over current detect state clear.
Wake up current detector
Wake up current detector detects approximate 1A current with
10mW sense resistor. Setting wake up current detect enable bit of
the wake up current detect control register 1(001216) “1”, wake up
current detector starts the operation. The sensing voltage is 10
times amplified and compared by the comparator. The comparator
is comparing every 3.9 msec, and more than 1A current is keeping
for about 62 msec, wake up current detect flag (bit 0 of 001316)
becomes “1”, and the wake up current detect interrupt occurs. The
enabling interrupt for wake up current detect is determined by
wake up current detect interrupt enable bit(bit6 of 001216). Setting
the wake up current detect restart bit “1” makes the wake up cur-
rent detect state clear.
The ofset calibration of the amplifier and comparator is able to be
adjusted by setting the wake up current compare voltage select
bit. Setting the wake up current detect calibration enable bit (bit 5
of 001416) “1”, calibration mode starts. In the calibration mode, in-
put of level shift circuit is connected to internal GND, and it is
possible to measure the comparator threshold voltage at 0 V input
state, with setting wake up current detect compare voltage select
bit. Then set the wake up current detect compare voltage select bit
the value which is added comparator threshold voltage at 0 V
state and 0.1V (1A worth voltage).
SFR protect control register
SFR protect control register (002916) protects SFR from changing
the contents easily cause of like microcomputer runs away.
When the bit of SFR protect control register is “0”, corresponded
bit register is protected. In case of writing to the protected register,
write “1” to the corresponded bit of protect register, then write the
protected register in succession. If other register is written, the
contents of SFR protect register is cleared “00”.
Rev.1.01 Aug 02, 2004 page 43 of 96