TL1454A, TL1454AY

DUALCHANNEL PULSEWIDTHMODULATION (PWM)

CONTROL CIRCUIT

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 CSCP

may be determined using Figure 6, or it can be calculated using:

C

SCP +

T

SCP

80.3

where CSCP is in µF and TSCP 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, VCC (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, TA: C suffix

−20

°C to 85°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storage temperature range, Tstg

−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

TA ≤ 25°C

POWER RATING

DERATING FACTOR

ABOVE TA = 25°C

TA = 70°C

POWER RATING

TA = 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