LT3003

4

3003fa

PIN FUNCTIONS

TYPICAL PERFORMANCE CHARACTERISTICS

LED1 (Pin 1): Controlled current input for a string of LEDs

with a cathode lead connected to the pin. Connect the first

string of LEDs to this pin.

LED2 (Pin 2): Controlled current input for a string of LEDs

with a cathode lead connected to the pin. Connect the sec-

ond string of LEDs to this pin.

LED3 (Pin 3): Controlled current input for a string of LEDs

with a cathode lead connected to the pin. Connect the third

string of LEDs to this pin.

• Buck Mode: Connect to Input Supply

the internal control circuitry.

• Boost: Connect to Input Supply

• Buck Mode: Connect to Input Supply

PWM (Pin 6): Input Pin for PWM Dimming Control. A

PWM signal above 0.5V (on threshold) turns the LT3003

channels on. A PWM signal below 0.5V completely discon-

nects each LED string. If the application does not require

PWM dimming, then the PWM pin can be left either open

(an internal 10µA source current pulls PWM high) or it

can be connected to a supply between 0.5V to 15V.

OT1 (Pin 7): Overtemperature Output. OT1 pulls 100µA

from the pin when the junction temperature exceeds

125°C. The part has to cool down by 6°C for the flag to

reset; ideal for providing an overtemperature flag to the

system microprocessor.

OT2 (Pin 8): Overtemperature Output. OT2 Pulls 300µA

from the pin when the junction temperature exceeds

125°C. The part has to cool down by 6°C for the flag to

error amplifier output to defeat switching.

SHDN (Pin 9): Micropower Shutdown Pin. Below 0.7V

• Buck Mode: Connect to System Shutdown Signal

• Buck-Boost Mode: If PWM dimming, connect to PWM

(Pin 6); if no PWM dimming, connect to system shut-

50

35

30

25

20

15

10

5

0

200

300

3003 G07

100

150

250

350

3

8

12

3003 G08

4

0

13

23

33

8

18

28

38

16

6

10

2

14

SHDN = 0