TDA3675 查看數據表（PDF） - Philips Electronics
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TDA3675 Datasheet PDF : 16 Pages
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Philips Semiconductors
Low dropout voltage/quiescent current
8.5 V voltage regulator with enable
Preliminary specification
TDA3675
EXAMPLE 1
The regulator is stabilized with an electrolytic capacitor of
68 µF (ESR = 0.5 Ω). At Tamb = −40 °C, the capacitor
value is decreased to 22 µF and the ESR is increased to
3.5 Ω. The regulator will remain stable at a temperature of
Tamb = −40 °C.
EXAMPLE 2
The regulator is stabilized with an electrolytic capacitor of
10 µF (ESR = 3.3 Ω). At Tamb = −40 °C, the capacitor
value is decreased to 3 µF and the ESR is increased to
20 Ω. The regulator will remain stable at a temperature of
Tamb = −40 °C.
EXAMPLE 3
The regulator is stabilized with a 100 nF MKT capacitor
connected to the output. Full stability is guaranteed when
the output current is larger then 200 µA. Because the
thermal influence on this capacitor value is almost zero,
the regulator will remain stable at a temperature of
Tamb = −40 °C.
For successful operation of the IC (maximum output
current capability) special attention has to be given to the
copper area required as heatsink (connected to all
GND pins), the thermal capacity of the heatsink and its
ability to transfer heat to the external environment. It is
possible to reduce the total thermal resistance from
125 to 50 K/W.
APPLICATION CIRCUIT WITH BACKUP FUNCTION
Sometimes a backup function is needed to supply, for
example, a microcontroller for a short period of time when
the supply voltage spikes to 0 V (or even −1 V).
This function can easily be built with the TDA3675 by using
an output capacitor with a large value. When the supply
voltage is 0 V (or −1 V), only a small current will flow into
pin REG from this output capacitor (a few µA).
The application circuit is given in Fig.6.
EXAMPLE 4
The regulator is stabilized with a 100 nF capacitor in
parallel with a electrolytic capacitor of 10 µF connected to
the output.
The regulator is now stable under all conditions and
independent of:
• The ESR of the electrolytic capacitor
• The value of the electrolytic capacitor
• The output current.
Application circuits
The maximum output current of the regulator equals:
IREG(max) = -R----t-h---(-j----a-1-)--5-×---0--(--–-V----PT----a–--m---V-b---R----E---G----)
= -1---0---01----5-×--0---(--–V----T-P---a-–--m---8-b--.--5----) (mA)
When Tamb = 21 °C and VP = 17.5 V, the maximum output
current equals 140 mA.
ndbook, halfpage
VP C1(1)
1 µF
VI (EN)
8
1
TDA3675
VREG = 8.5 V
C2(2)
5
2, 3, 6, 7
MGL832
VI(EN) = 5 V.
(1) C1 is optional (to minimize supply noise only).
(2) C2 ≤ 4700 µF.
Fig.6 Application circuit with backup function.
2000 Feb 01
7
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