Datasheet
9397 750 15049 © Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Product data sheet Rev. 05 — 28 June 2005 3 of 16
Philips Semiconductors
TDA3661
Very low dropout voltage/quiescent current voltage regulator
6.2 Pin description
[1] All GND pins are connected to the lead frame and can also be used to reduce the total thermal resistance
R
th(j-a)
by soldering these pins to a ground plane. The ground plane on the top side of the printed-circuit
board acts like a heat spreader.
7. Functional description
The TDA3661 is an adjustable voltage regulator with an output voltage that can be fixed
by means of an external resistor divider. The regulator can deliver output currents up to
100 mA. The regulator is available in an SO8 package. The regulator is intended for
portable, mains and telephone applications. To increase the lifetime of batteries, a
specially built-in clamp circuit keeps the quiescent current of this regulator very low, in
dropout and full load conditions.
The device remains operational down to very low supply voltages (typical 2 V) and below
this voltage it switches off. A temperature protection is included which switches off the
regulator output at a junction temperature above 150 °C.
8. Limiting values
9. Thermal characteristics
Table 3: Pin description
Symbol Pin Description
REG 1 regulator output
GND 2, 3, 6 and 7 ground
[1]
n.c. 4 not connected
ADJ 5 feedback input
V
P
8 supply voltage
Table 4: Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol Parameter Conditions Min Max Unit
V
P
supply voltage - 45 V
V
P(rp)
reverse polarity supply
voltage
non-operating - −25 V
P
tot
total power dissipation temperature of
copper area is
25 °C
- 4.1 W
T
stg
storage temperature non-operating −55 +150 °C
T
amb
ambient temperature operating −40 +125 °C
T
j
junction temperature operating −40 +150 °C
Table 5: Thermal characteristics
Symbol Parameter Conditions Typ Unit
R
th(j-c)
thermal resistance from junction to case to center pins; soldered 30 K/W
R
th(j-a)
thermal resistance from junction to ambient in free air; soldered 155 K/W