Datasheet
SLVS423 A− MAY 2002 − REVISED SEPTEMBER 2002
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
short-circuit protection (SCP) (continued)
The SCP time-out period must be greater than the converter start-up time or the converter will not start. Because
high-value capacitor tolerances tend to be ±20% or more and IC resistor tolerances are loose as well, it is best
to choose an SCP time-out period 10-to-15 times greater than the converter startup time. The value of C
SCP
may be determined using Figure 6, or it can be calculated using:
C
SCP
+
T
SCP
80.3
where C
SCP
is in µF and T
SCP
is the time-out period in ms.
output stage
The output stage of the TL1454A is a totem-pole output with a maximum source/sink current rating of 40 mA
and a voltage rating of 20 V. The output is controlled by a complementary output AND gate and is turned on
(sourcing current for OUT1, sinking current for OUT2) when all the following conditions are met: 1) the oscillator
triangle wave voltage is higher than both the DTC voltage and the error-amplifier output voltage, 2) the
undervoltage-lockout circuit is inactive, and 3) the short-circuit protection circuit is inactive.
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
Supply voltage, V
CC
(see Note 1) 23 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Error amplifier input voltage: IN1+, IN1−, IN2+, IN2− 23 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output voltage: OUT1, OUT2 20 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output current: OUT1, OUT2 ±200 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Peak output current: OUT1, OUT2 1 A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous total dissipation See Dissipation Rating Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
: C suffix −20°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
−65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
†
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: All voltage values are with respect to network GND.
DISSIPATION RATING TABLE
PACKAGE
T
A
≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE T
A
= 25°C
T
A
= 70°C
POWER RATING
T
A
= 85°C
POWER RATING
D 950 mW 7.6 mW/°C 608 mW 494 mW
DB 1000 mW 8.0 mW/°C 640 mW 520 mW
N 1250 mW 10.0 mW/°C 800 mW 650 mW
NS 1953 mW 15.6 mW/°C 1250 mW 1015 mW
PW 500 mW 4.0 mW/°C 320 mW 260 mW