ltm8040 Linear Technology Corporation, ltm8040 Datasheet - Page 5

• Manufacturer Part Number: ltm8040
• Description: 36v, 1a ?module Led Driver
• Manufacturer: Linear Technology Corporation

PIN FUNCTIONS
TYPICAL PERFORMANCE CHARACTERISTICS
LEDA (Bank 1): This pin is the regulated current source
of the LTM8040. Connect the anode of the LED string to
this pin. This voltage must be at least 2.4V for accurate
current regulation.
SHDN (Pin L4): The SHDN pin is used to shut down the
switching regulator and the internal bias circuits. The
2.65V switching threshold can function as an accurate
undervoltage lockout. Pull below 0.3V to shut down the
LTM8040. Pull above 2.65V to enable the LTM8040. Tie
to V
IN
if the SHDN function is unused.
47
42
37
32
27
22
17
12
37
32
27
22
17
12
7
2
7
2
Temp Rise vs Load 2.7V at 1A
LEDs, 36V
0
Temp Rise vs Load 3.3V at 1A
LEDs, 36V
0
200
200
SINGLE LED
2 LEDs
3 LEDs
4 LEDs
SINGLE LED
2 LEDs
3 LEDs
IN
IN
400
400
I
I
LOAD
LOAD
(mA)
(mA)
600
600
800
800
8040 G16
8040 G18
1000
1000
BIAS (Pin L5): The BIAS pin connects through an internal
Schottky diode to provide power to internal housekeeping
circuits. Connect to a voltage source (usually LPWR or V
greater than 3.2V. Note that this pin is adjacent to the LPWR
pin to ease layout. If this pin is powered by an external
power source, a decoupling cap may be necessary.
LPWR (Pin K5): This is the output of the buck regulator
that sources the LED current. If the LEDA voltage is above
3.2V, connect this pin to BIAS. It is pinned out primarily
for the convenience of the user. If it is not used, leave this
1200
1000
800
600
400
200
27
22
17
12
0
7
2
0
0
Temp Rise vs Load 3.3V at 1A
LEDs, 12V
LED Current vs Adjust Voltage
200
200
SINGLE LED
2 LEDs
3 LEDs
400
IN
ADJUST VOLTAGE
400
I
LOAD
600
(mA)
600
800
1000 1200
800
8040 G19
8040 G17
1000
LTM8040
5
8040p
IN
)