TD230IDT STMicroelectronics, TD230IDT Datasheet

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TD230IDT

Manufacturer Part Number
TD230IDT
Description
MOSFET & Power Driver ICs
Manufacturer
STMicroelectronics
Datasheet

Specifications of TD230IDT

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INTRODUCTION
Over current and short circuit protection is a con-
stant concern for today’s engineers. More and
more applications in different segments (Telecom,
Automotive, Industrial, Computer...) require al-
ways improved reliability after delivery : mainte-
nance costs are an ever more worrying source of
expenses and customers’ dissatisfaction.
Alternatives for short circuit or over current protec-
tions are the fuses and the PTC (Positive Temper-
ature Coefficient) resistors. The first are a cheap
but destructive solution ; the second are tied to a
time constant due to self heating which is often in-
compatible with the host equipment’s require-
ments.
In both cases, a coil can be added for an efficient
limitation of current surges, to the detriment of
weight and volume.
None of these solutions is fully satisfactory for a
reliable, immediate and non destructible short cir-
cuit and over current protection.
1. ELECTRONIC CIRCUIT BREAKER
The electronic circuit breaker TD230 is the conve-
nient solution for any industrial who wants at the
same time :
The electronic circuit breaker TD230 is to be used
with a minimal amount of external and low cost
components to drive one or two N-channel MOS-
FETs (in respectively single or dual supply appli-
cations) used as power switches between the DC
power supplies and the equipments to be
protected.
The TD230 immediately reacts (3 s max. without
load) whenever an over current is detected by
switching off the corresponding MOSFET. Several
automatic restart attempts are made unless the
fault persists over an externally adjustable amount
of time after which the power MOSFET is defini-
tively switched off, waiting for a reset.
May 2000
immediate, efficient and resettable protec-
tion for his equipment
versatility regarding different applications
easy and quick design-in
low component count
low cost
TD230: ELECTRONIC CIRCUIT BREAKER
If the fault is detected on the positive supply, the
definitive shutdown will also disconnect the nega-
tive power supply and set a warning low level on
the Shutdown pin. If the fault is detected on the
negative supply, the definitive shutdown will dis-
connect only the negative power supply, and let
the positive part of the circuit undisturbed.
The whole system can be reset in three ways :
2. HOW TO USE THE TD230 ?
The typical configuration of the TD230 - Electronic
Circuit Breaker - in a dual supply topology is
shown in figure 1.
In this configuration, both NMOS 1/2 are used as
power switches which connect the equipments to
the power supplies, thus ensuring low voltage
drop through the ON-resistances (Rdson) of
NMOS
2.1. Current Limitation
When an over current condition (I
through the low ohmic shunt resistors R
en under equation (i) :
the gate of the corresponding MOSFET 1/2 is dis-
charged immediately, thus disconnecting the
board/equipment from the power supply.
Note that the over current condition is given by the
constant product I
that the IOC limit is directly given by the choice of
the shunt resistors R
The TD230 automatically makes restart attempts
by slowly recharging the gate of the MOSFET
with a 15 A typ. current source ensuring thus slow
ramp with the typical time constant before recon-
duction shown in equation (ii) :
where CISS is the input capacitance of the power
MOSFET
MOSFET (typically 5V).
APPLICATION NOTE
by switching off the power supplies
by unplugging and re-plugging the card
(live insertion)
by setting the INHIBIT pin active during a
short time (allowing remote reset)
1/2
V
t
ON
RS 1/2
.
1/2
= CISS x VTH / 15 A (ii)
and VTH, the threshold voltage of the
= I
OC
OC
x R
S1/2
x R
S
> 63mV typ. (i)
values.
S
= 63mV, which means
AN1280
OC
) is detected
S 1/2
by R. LIOU
as giv-
1/8
1/2

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TD230IDT Summary of contents

Page 1

INTRODUCTION Over current and short circuit protection is a con- stant concern for today’s engineers. More and more applications in different segments (Telecom, Automotive, Industrial, Computer...) require al- ways improved reliability after delivery : mainte- nance costs are an ever ...

Page 2

This reconduction time can be extended with an external soft start capacitor C SS1/2 figure 1 C will therefore simply be replaced by ISS ISS SS 1/2 Figure 1 : Dual Electronic Circuit Breaker Application If ...

Page 3

AN1280 - APPLICATION NOTE To avoid cumulative charging of the protection ca- pacitors C in case of successive overcurrent TRIP 1/2 conditions, the capacitors C TRIP 1/2 discharged by another fixed current source IP/N3 which value is a fourth of ...

Page 4

Proper operation of this step-up converter is guar- anteed at as low as 2.7V with a rise time (0 to 90 the range of 700 s at 2.7V which BOOST is the worst case. At 5V, ...

Page 5

AN1280 - APPLICATION NOTE Figure 8 : Decentralized Protection Therefore, when a fault appears on the positive rail, the definitive shutdown of the positive NMOS will lead to the shutdown of the negative NMOS, but when a fault appears on ...

Page 6

Figure 9A: PCB (not to scale) Figure 9C: Schematic 4. The SHUTDOWN pin is an open drain CMOS/ TTL compatible output which should be tied to the TTL compatible input of an eventual control block. The absolute maximum rating of ...

Page 7

AN1280 - APPLICATION NOTE Figure 10 : Visual Alarm-Shutdown where ISS1/2 SS1/2 TH1/2 P/N1 the input capacitance, the soft start capacitor, the threshold voltage and the internal gate current sources of NMOS ; ...

Page 8

... No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied ...

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