2

LT1572

A

G

A

U

A

R

BSOLUTEXI

TI

S

PACKAGE/ORDER I FOR ATIO

Supply Voltage (Note 4).......................................... 40V

Switch Output Voltage (Note 4) .............................. 60V

Feedback Pin Voltage (Transient, 1ms) ................

±15V

Operating Junction Temperature Range

Operating .............................................. 0

°C to 100°C

Short Circuit ......................................... 0

°C to 125°C

Storage Temperature Range ............... – 65

°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300

°C

DIODE

Average Forward Current .......................................... 1A

Peak Repetitive Forward Current .............................. 2A

Peak Non-Repetitive Forward Current ....................... 3A

Peak Repetitive Reverse Voltage ............................. 20V

Continuous (Average) Reverse Voltage .................. 15V

Operating Junction Temperature ......................... 125

°C

Note 1: Minimum effective switch “on” time for the LT1572 (in current

limit only) is

≈ 0.6µs. This limits the maximum safe input voltage during

an output shorted condition. Buck mode and inverting mode input voltage

during an output shorted condition is limited to:

buck and inverting mode

R = Inductor DC resistance

t = 0.6

µs, f = 100kHz switching frequency

ORDER PART

NUMBER

LT1572CS

R

t

× f

External current limiting such as that shown in AN19, Figure 39, will

provide protection up to the full supply voltage rating. C1 in Figure 39

should be reduced to 200pF.

Transformer designs will tolerate much higher input voltages because

leakage inductance limits rate of rise of current in the switch. These

designs must be evaluated individually to assure that current limit is well

controlled up to maximum input voltage.

Boost mode designs are never protected against output shorts because

the external catch diode and inductor connect input to output.

ELECTRICAL C

C

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Reference Voltage

Measured at Feedback Pin

1.224

1.244

1.264

V

q

1.214

1.244

1.274

V

Feedback Input Current

350

750

nA

q

1100

nA

Error Amplifier

3000

4400

6000

µmho

Transconductance

q

2400

7000

µmho

Error Amplifier Source or

150

200

350

µA

Sink Current

q

120

400

µA

Error Amplifier Clamp

1.80

2.30

V

Voltage

0.25

0.38

0.52

V

Reference Voltage Line

3V

q

0.03

%/V

Regulation

Error Amplifier Voltage Gain

0.9V

500

800

V/V

Minimum Input Voltage (Note 3)

q

2.6

3.0

V

Supply Current

3V

6

9

mA

Consult factory for Industrial and Military grade parts.

TOP VIEW

S PACKAGE

16-LEAD PLASTIC SO

*ALWAYS CONNECT BOTH ANODE

AND BOTH CATHODE PINS

SEE THERMAL MANAGEMENT SECTION FOR

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

NC

ANODE*

CATHODE*

GND

FB

NC

NC

NC

ANODE*

CATHODE*

GND

E2

E1