TD230IDT STMicroelectronics, TD230IDT Datasheet - Page 7

• Manufacturer Part Number: TD230IDT
• Description: MOSFET & Power Driver ICs
• Manufacturer: STMicroelectronics

Specifications of TD230IDT

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AN1280 - APPLICATION NOTE
Figure 10 : Visual Alarm-Shutdown
where C
the input capacitance, the soft start capacitor, the
threshold voltage and the internal gate current
sources of NMOS
N2
source and external capacitor of the protection
mode pins PM
V
MOSFETs have a threshold voltage around 5V,
this condition can be translated to inequation (vi) :
If C
superior to 4.56nF.
Table (b) summerizes Protection Mode Time
Constants corresponding to different C
ues.
Table (b) : Protection Mode Time Constants
5. ENHANCEMENTS
The performances of TD230 are well adapted to
most of the circuit breaking applications in many
differents industry segments (Telecom, Automo-
tive, Industrial, Computer etc...), but in the case of
very demanding environment, or outstanding fea-
tures, the few following advices may be helpful.
5.1. Step-Up Noise Reduction
The inductive step-up converter inevitably gener-
ates current peaks in the output of the power
SP1/2
are respectively the voltage source, current
ISS
, I
= 1nF and C
P/N2
C
ISS1/2
TRIP1/2
, I
C
220nF
2.2 F
22nF
22 F
TRIP1/2
P/N1
, C
1/2
> 0.8 x (C
, and the fact that classical power
. Considering the typical values of
SS1/2
1/2
SS1/2
; and where V
, V
= 4.7nF, C
TH1/2
SS1/2
, I
Time Constant Range
+ C
for Protection Mode
P/N1
ISS
- Shutdown -
are respectively
SP1/2
TRIP1/2
) (vi)
#100ms
#10ms
#10s
#1s
, C
should be
TRIP1/2
TRIP1/2
val-
, I
P/
switch which, in most cases are, are not worrying.
But in some very demanding applications, it is
necessary to remove this noise.
A good way to eliminate such peaks is to add a re-
sistor connected in series with the inductance and
an electrolytic capacitor between the common
point of resistor and inductance, and ground of the
Step-Up Converter as shown on figure 11.
Figure 11 : Step Up Noise Reduction
The resistor’s voltage drop will be due to the prod-
uct of the average consumption current with the
resistor’s value and the inductive current peaks
will be totally absorbed by the capacitor. With a
100
the attenuation good with a 4.7 F as shown on
figure 12.
Figure 12 : Step Up Noise Reductio
resistor, the voltage drop is negligible and
7/8