MOTOROLA
@
Prototype
Information
MC33345
1 to 4 Cells Lithium Battery Safety IC
The MC33345 is a Lithium Battery Safety GreenLine~
Integrated
Circuit designed to control the charge and discharge voltage safety
limits of one to four
/ifhium-ion
or
/ithium po/ymer
rechargeable cells.
This device is designed to be placed inside the battery pack
together with the cells and other external components to form a smart
battery pack. Its main purpose is to ensure safe battery pack while
charging or discharging.
The circuit also protects the integrity of the Lithium cells. In effect, it
avoids the degradation of the cells in case of overdischarge by causing
the battery pack to go in a zero current SLEEPfvfODEw State. This
state interrupts any further leakage of the cells.
Charge
q
Control
:
\
q
q
q
Fully programmable
for 1 to 4
Lithium-/on
(Li-ion) or
Lithiu~~~
“,:..~~’+
\\ ,$<,.,.
Po/ymer
Rechargeable Cells.
Precision Cell Voltage Measurement with an Accuracy of 1Yti, “h~j
.,,,;:.:
.J,i.>.{,
\
Programmable Voltage and Current Limits.
~
$.,*, .\:>
Automatic Cell Balancing for Optimization of the Ch:$$e’’$feach
?,>,.,s
*.h
,.,.
?,*,:ii::.,~.*
Cell.
, .\ J $
-’ :..’
/ \‘~’{.F:*.
.!:::,,
DTB SUFFIX’
PLASTC PACKAGE
CASE WE42
~so
P-20)
q
Protection
Features
:
.8*
20
DW SUFFIX’
PLASTC PACKAGE
CASE
7510-03
(SO -20L)
q
q
Zero Current
SLEEPMODE~
State i~:,~~~der to avoid the
Degradation of a Cell in the Event of an ~~wltage
Condition.
Overvoltage and Undervoltage Cell PrW$~$~fi.
Overcurrent Protection during Char@’@@:Discharge.
/:.’\>,a,
$\,;.. ‘.~~.’
.!...\\,
for Smart
Battery
Pack~@3@ation
,.
$1.., :.ji.‘~l
:
Designed
q
Available in
S0-20
Wide ~@d@%#d Low Profile TSSOP-20
Thickness) Surface MoU~~$a&ages.
,...
(\., ~~,:~\
,y. \.
SLEEPMODE and Gree,,pSf&$w~&
trademarks of Motorola, Inc.
‘:’’+~l
,2
(1 mm
PIN CONNECTIONS
_ ~
Ref_Gnd
1
Vcc
Mux+
Vlow :
2
_
20
19
V3
V2
3
n
Drain
rge Gate
5
6
I
——
-1,
‘high
Over Discharge
16 Gnd
15
Test
B-
rge Pump
>utPin
13
~scharge
Gate
12
R
Not Connected
Over Charge 7
Pack-
ChargeGate
8
9
Prog 2 10
11 Pro{
ce’”-~
II
.... ...-
1
I
~1
.–
This document contains information on a new product. Specifications
herein are subject to change without notice.
and information)n
I
ORDERING
!
INFORMATION
I
I
I
@ MOTOROLA
INC., rev:
11 November
1995
MC33345
LITHIUM BA~ERY
SAFETY IC
MAXIMUM
RATINGS
Rating
Pin no
Symbol
Value
Unit
CELL VOLTAGE
LIMITS,
Vov and Vuv (w/ 0.1Y. program resistors)
,,:,.?*-
..,.*
!,+J\\<,.
,
Voltage limit accuracy
Cell programmable voltage limit range
Minimum total programming resistance
Program pin voltage for 4 cells
,,.t~,
,*3
.,,
:1, ~‘i .<)’$
,:,3, ~
,.> *,-
... .,%
.
!!,.<,:;<,’,.,
,!y..:$
1.25
,,,,, ~-::
,.?...
.
.~:,.. A,.
....$..::*:.:
100k
\
,.., J“*,
o
.:<$,.
*
0.5%
–
+
1
0/0
5
v
Q
VI
v
s~.
CURRENT
LIMIT, CHARGE
AND DISCHARGE
(sensed acrosst~{~~xrs
-.
Charge current voltage limit
Discharge current voltage hmit
Current Discharge Limit Delay
Current Charge Limit Delay
* . ~~
$.’
.~:\*<.J,:*,
.
\
~l?.’ “$x
?$’J
\i.
.,
\i>.,\ ~>,
,,,\,>.> ~.?
.,,\,,, I
,,,,. lb,
,:t) .’$.,.,,
~,.,,
...t,~a
,,eJ$
10
2
.,,.
.>
*,
in current path)
14
50
20
3
mV
mV
,..
N.?.
t.
ms
s
SUPPLY
.,,..
,,
Voltage range of sum of series c@i21.$
.?J
Awake Drain current at V2 q~~$~%~s.
v
Awake Drain current at ~~a#q}:,fF
Sleep
mode current ,at ~~,~n
Charge
PurnP vo\~*
.J$e
2.2
3
15
20
5
v
pA
20
1
@
nh
i
V3 pin
8
10
2
12
10
v
nA
Awake
Drain$@f~@$~t
Awake D~~;@~&%rent Vcc pin
at
5
6
PA
~perating
Ambient Temperature
-40
-55
85
150
‘c
“c
Storage Temperature
minimum
q
and maximum
specifications
preliminary
only, subject to verification
with final product testing.
MOTOROLA
MC33345
2
MC33345
PIN No
NAME
PIN DESCRIPTION
I
1
Ref_Gnd
Connected to the lower multiplexer output on the MC33345, which selects the cell voltages
for measurement. Has the third of three external resistors connected to it for programming
the upper and lower voltage limits. Max. rated voltage of 18V.
Connected to the top cell in the series string of the battey
pack. Pin rated for 18V.
.
..!~
2
v~~
3
Mux+
Connected to the upper multiplexer on the MC33345, which selects the batie~i-
for measurement. Has the first of three external resistors connected to it for @~@ming
the the cell voltage timits. This input pin will survive 20V, sinking approxi@~~b~
,
>,$3.,.1**<,
maximum while the cells are being polled.
$?,,$< ‘~:’
$
.f~$
.i*] “ ‘.,..,:t
Connected to the lower tap point of the three programming resist~~s~~~~;y coupled
between Mux+ and Ref_Gnd. This connection sets the undew~~g$~~it.
Rated for 30V.
~.-:,,.i,,,
.*..
‘.’.::,>
.
Connected to the upper tap point of the three programmin~:wtors
serially coupled
between Mux+ and Ref_Gnd. This connection sets th~jwrtage
limit. Rated for 30V.
,;* .,.
sinks approximately
200nA.
4
Vlow
5
‘high
6
Over Discharge
7
Over Charge
sinks approximately
200nA.
!t$ ::,;,?,,$$
8
Pack-
9
Charge Gate
Connected to the negative terminal o$~e battery pack, to the source terminal of the exter-
nal Charge FET. Rated for 15V3$~:r ‘*’
.,,.. !,
Drives the gate of the Char~~F~.
To be connected to gate of etiernal FET to control
charge current. Rated f~. .)i?,):\<,J+\t,
?~~:’
J
.1
,,,,, ,
Least significant bit of ~os~rogram pins for choosing the number of cells to be monitored
by the MC3334~JReference
table 1 for encoding. Rated for 7V, high impedance input.
W*
.
Most signifi~.~~~t
by the MWX.
, $>,, :,
of two program pins for choosing the number of cells to be monitored
Reference table 1 for encoding. Rated for 7V, high impedance input.
10
Prog2
11
12
13
Progl
14
15
{j “” ~stifiarge current. Rated for 18V.
:
b.
J
““‘ “?”An external O.lpF capacitor is required here for proper operation of the MC33345.
Charge Pum#}’ “j
output ,qf*~~s’
Maximum output voltage of 12V.
..~,. ,..
b
“v.y
..*)S+’
‘,,,r
Test pin used to reset logic on the MC33345. The voltage applied to reset the logic must
,
,‘,.$3’
,,$
be equal to -V1. The test pin resets all 14 D flip-flops in the control circuit~. The next
,,,&\i;+&<
clock pulse from the on chip oscillator will begin the cell measurement process. Maximum
‘,{
,x‘ ..t).A*,:i*,i,
* ‘:,:$
~ ‘~
‘r.\ .:,;$,
rated voltage of 10V.
$.
,2;...y{}~,,,
Gnd
Open Drain
Charge Gate
Ground pin for MC33345, to be connected to the cathode of the last cell in series batte~
string and source of the Discharge Ffl (see Fig. 1).
Open Drain output which pulls low when Cgate is low, i.e. when a cell is measured over-
voltage. Maximum voltage rating of 18V, ma. current of 10 mA.
Input to multiplexer that is tied to the cathode of cell two and the anode of cell one (see
Fig. 1). Max. rated voltage of 18V.
Input to multiplexer that is tied to the cathode of cell three and the anode of cell MO (see
Fig. 1). Max. rated voltage of 18V.
Input to mu[tiplexers that is tied to the cathode of cell four and the anode of cell three (see
Fig. 1). Max. rated voltage of 18V.
Discharge Gate
No~&;%~ed
,,,,.,$>i-,,.
‘ ,,.<,
\
+~~~the
gate of the Discharge FET. To be connected to gate of external FET to control
18
V1
19
V2
20
V3
MOTOROU
MC33345
3
MC33345
OPERATING
PurDose
The Lithium Battery Safety IC is designed for smart
battery applications.
The smart battery pack consists of
one to four cells, the MC33345,
and some external
components,
such as resistors. The number of cells
monitored is programmed
by two pins on the circuit. The
circuit places two series FETS between the most negative
voltage in the serial string of cells and the negative
terminal of the battery pack, as seen in Fig. 1. These FETs
are controlled by an algorithm based upon the individual
cell voltages and current limits for charge and discharge.
DESCRIPTION
Voltaqe Limit Proqramminq
MC33345
measures
The
the
cell
voltages
approximately
1m’s per 1.5 seconds,
using a pair of
multipiexers to select each series cell. The output of these
multiplexer,
which represents
each cell voltage,
is
compared with a zero temperature coefficient voltage. The
result of the comparison is clocked into the ap~opriate
<<,
undervoltage or overvoltage flip flop.
*#$::\\\.<:,::,
~
.J*’,,.~,.~
These flip flops eventually control the ~oW@to
the
series charge and discharge
FETS. .@@$Q@een
ceil
measurements,
the MC33345 circui~:~:~~jti
a standby
mode to reduce drain current fr~~$th~hatte~.
This
The FETs are capable of interrupting
current flow of
sampling methodology
decreasWt’#&;!~>rnount
of current
either polarity in the battery. The main purpose of the
drain on the ceils compar~dy~:~$?other
measurement
MC33345 is to ensure safety while a customer charges
..
,,.~.t
,,.,
methods.
..1..‘S*
and discharges the lithium battery pack. The MC33345
~,. ..,X.:X
,\.,,~$,>
,,,~,.
also protects the integrity of the cells. For example, the
A bandgap voltage,:~~mrator
is
used
for simplified
cycle life of the battey
is degraded
when cells are
design of a compara~:~~~,~a
zero temperature coefficient
overdischarged
past a lower voltage limit. The circuit
reference. The baw~’dircuit
has six bits of trim, using
causes the battery pack to go to “sleep” when any cell
zener diodes,,f~$a
1’% accuracy.
~.i~’> ~,.
,,.!,>\!,:,
>>
reaches the lower voltage limit, thereby interrupting any
The up~~,~d~ower
voltage limits for the cells are set
further leakage of the cells.
by thre~~te~$al
program resistors, serially coupled from
the M@~#’~ti’~o the Ref_Gnd pin, as shown in Fig. 2. The
Fig. 1. Battery Pack.
h~$~ere~b voltage, which is a function of (R1 + R2)*2wA,
.~i$~:~~+:iamount a cell must discharge below the overvoltage
$ li~$t before
the comparator
considers
the cell “not
VCC(2) o
q
‘?$
7$:$1
~-,.
,\. @W~rvoltage”. A typical example showing how to calculate
Pack+
*:& *:T&. voltage programming limits and hysteresis voltage can
,& the
.. ‘“ be found at the end of the operating description.
The voltage limits and hysteresis
voltage are :
Vhigh = 1.23*(R1 +R2+R3)
R3
VIOW= 1.23*(R1 +R2+R3)
R2+R3
‘hysteresis
=
2pA*(Rl +R2)
Gnd(16)*--
Fig. 2. Programming
Resistors for Upper
Voltage Limits.
and Lower
:,>, ~.
.,(\::,Y:*f,.~
~.,,f’
..J,,.,,
... ~~~hium
technology requires careful control of cell
~$\@w4 and current levels for safety and long life. Series
$:*
pmer FETs on the MC33345 can interrupt current flow in
a charging
or load situation,
depending
upon the
undervoltage
and ovewoltage
condition
of each cell.
Overcharge current and overdischarge
current protection
are externaihj programmable.
Cell balancing is also provided; on-chip FETS balance
cells based on overvoltage
information.
Cell balancing
ensures the optimum
amount
of eticiency
when the
battery is in use. The MC33345 is fabricated in a mixed-
mode BiCmos process.
Mux+
(3):
’”’
“
RI
V,ow (4)
vhigh (5)
.,
Ref_Gnd (1 )
3
R2
R3
MOTOROLA
MC33345
MC33345
“Sleep “
Mode
The MC33345 switches to an ultra low drain current
mode called <<Sleep~>mode when any cell is detected in
undervoltage. This is to avoid damage to cells in an
undewoltage
condition. When an undervoltage cell is
found, the circuit interrupts discharge current, and goes
into a
“sleep” mode until returned to a charger. In the
sleep mode, the system clock and the charge pump are
turned off, reducing drain current to an extremely small
value
which is a function of leakage currents on the
MC33345.
Once placed in a charger, the MC33345
returns to its regular operation.
Cell Balancinq
The cell balancing function takes place when a cell(s)
is in an overvoltage condition while another cell(s) is not.
An overvoltage measurement
on a particular ceil is
clocked into a flip flop representing the cell position in the
battery pack.
After all cells have been measured, the flip flops are
checked to see if all cells match the same cond4jon.
If
some cells are overvoltage and others still @#b
this
level, the overvoltage cells have a para\@l$g&T
and
$. :,:.,.
t
, *e.,’!
:>..,,
resistor activated.
,..:$4?::
,., .,
:
This causes a current drain fro~ “@$$articular
cell
until the cell discharges a
ValUe vh~&~~
~“%elow the upper
voltage limit. In other
words, t~$’~Q&&nced
ceil(s) must
discharge
below Vhigh - ~~Y~t@S
before they ]Ose
.,,,,~e,
:+: .*}
ovewoltage status.
* .\
,**?
,;\:\&
%<.,,!
.}~i>
The current drai~$~~f$%
cell during balancing
is
dependent upon the ~~~;t~’~ 40 Q parallel resistor used for
balancing. The ce~wncing
is complete when all cells
reach ovewol~%
sf&tus while being charged.
If all cells
read ove~,~{~~w:%l the same-time, none are discharged
by the pa~lld~*Ts
and resistors.
,::::‘+$, <,,
>+y ~til,~z
,....,j”~
,,, V,v?
~ti.s
Charqe
Pump
Other functions on the MC33345 include an on-board
charge pump, which powers
the series FETs, and an
oscillator, which provides the timing clock for the circuit.
Proqrammina
the Number of Cells
The MC33345
is programmable
for operating
with
battery systems of 1 to 4 cells.
Pins Prog2 (n”l O) and
Progl (n”l 1) are used to set the number of cells the
MC33345 is to monitor. The program pins are defined by
wiring the pin to either Gnd (n”l 6) or the V1 pin (n”18).
urrent Limit Proaramminq
+s$~~
>P,$.? ‘“;
\’”*.\
f.:. $,
.:*,%., ‘
The overcharge current and overdischarge
‘:+:
>,*%+?’
current are
Rc corresponds to the overcharge current resistor, RD
tO the overdischarge
CUrrent reSiStOr.
AVbe
CUrrent mhrOrS
are used to detect each current limit. The current limits
are programmed by the following equations:
Rc = 14mV
lcharge
and
RD = 50mV
‘discharge
Fig. 3. Overcurrent
Programming
of MC33345
c~h
I
it
1
I
For example, a one cell battey would have its cell
positioned between VI and Grid, with V2, V3, and Vcc all
shorted to V1.
OV Char.
‘ack+k
(7) ~
OV Disch.
(6)
T
~
I
I
I
“3 (20)
etc
MOTOROLA
MC33345
5
