PBL 386 30/1
Secondary Protection
Tertiary Protection
device. Without the capacitor even the low
inductanceinthetracktotheVBatsupplywill
limit the current and delay the activation of
the thyristor clamp.
The fuse resistors RF serve the dual
purposes of being non- destructive energy
dissipators, when transients are clamped
andofbeingfuses,whenthelineisexposed
to a power cross.
EricssonComponentsABoffersaseries
of thick film resistors networks (e g PBR
51- series and PBR 53-series) designed
for this application.
Alsodeviceswithabuiltinresetablefuse
function is offered (e g PBR 52-series)
including positive temperature coefficient
(PTC)resistors,workingasresetablefuses,
in series with thick film resistors.
Thecircuitshowninfigure11utilizesseries
resistors together with a programmable
overvoltage protector
(e.g. Power Innovations TISPPBL1), ser-
ving as a secondary protection.
ThePBL38630/1SLICfeaturesatertiary
two wire protection scheme.
If the secondary protection device and
the SLIC do not have their respective
grounds shorted together on the printed
circuit board, the protection resistors RP1
and RP2 (see figure 11) together with the
SLIC's internal tertiary protection circuitry,
will handle the ground voltage difference
that may occur when the secondary
protection circuitry is activated.
The TISPPBL1 is a dual forward-con-
ducting buffered p-gate overvoltage
protector. The protector gate references
theprotection(clamping)voltagetonegative
supply voltage (i e the battery voltage, VB).
As the protection voltage will track the
negative supply voltage the overvoltage
stress on the SLIC is minimized.
Positive overvoltages are clamped to
ground by a diode. Negative overvoltages
are initially clamped close to the SLIC
negative supply rail voltage and the
protector will crowbar into a low voltage on-
statecondition,byfiringaninternalthyristor.
A gate decoupling capacitor, C GG, is
needed to carry enough charge to supply a
high enough current to quickly turn on the
This voltage difference arises due to the
ground lead inductance.
Power-up Sequence
No special power-up sequence is
necessary except that ground has to be
presentbeforeallotherpowersupplyvolta-
ges.
Note that it is important to always use
PTC´s in series with resistors not sensitive
to temperature, as the PTC will act as a
capacitanceforfasttransientsandtherefore
will not protect the SLIC.
Printed Circuit Board Layout
thyristor in the protector. C
shall be
GG
Care in PCB layout is essential for proper
function. The components connecting to
the RSN input should be placed in close
proximitytothatpin, sothatnointerference
is injected into the RSN pin. Ground plane
surrounding the RSN pin is advisable.
Analog ground (AGND) should be
connected to battery ground (BGND) on
the PCB in one point.
placed close to the overvoltage protection
Ordering Information
Package
Temp. Range
-40° - +85° C
-40° - +85° C
Part No.
PBL 386 30/1SO
PBL 386 30/1QN
24 pin SOIC
28 pin PLCC
24 pin SOIC Tape & Reel
-40° - +85° C PBL 386 30/1SO:T
The capacitors for the battery should be
connected with short wide leads of the
same length.
28 pin PLCC Tape & Reel -40° - +85° C PBL 386 30/1QN:T
Information given in this data sheet is believed to be
accurate and reliable. However no responsibility is
assumed for the consequences of its use nor for any
infringement of patents or other rights of third parties
which may result from its use. No license is granted by
implication or otherwise under any patent or patent
rights of Ericsson Components. These products are
sold only according to Ericsson Components' general
conditions of sale, unless otherwise confirmed in
writing.
Specifications subject to change without
notice.
1522-PBL 386 30/1 Uen Rev. D
© Ericsson Components AB 1998
This product is an original Ericsson
product protected by US, European and
other patents.
Ericsson Components AB
S-164 81 Kista-Stockholm, Sweden
Telephone: +46 (0)8 757 50 00
4-208
ERICSSON [ ERICSSON ]
