LTM8040 Ver la hoja de datos (PDF) - Linear Technology
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LTM8040 Datasheet PDF : 16 Pages
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TYPICAL PERFORMANCE CHARACTERISTICS
LTM8040
Temp Rise vs Load 2.7V at 1A
LEDs, 36VIN
47
SINGLE LED
42
2 LEDs
3 LEDs
37
4 LEDs
32
27
22
17
12
7
2
0
200 400 600 800 1000
ILOAD (mA)
8040 G16
Temp Rise vs Load 3.3V at 1A
LEDs, 36VIN
37
SINGLE LED
32
2 LEDs
3 LEDs
27
22
17
12
7
2
0
200 400 600 800 1000
ILOAD (mA)
8040 G18
Temp Rise vs Load 3.3V at 1A
LEDs, 12VIN
27
SINGLE LED
2 LEDs
22
3 LEDs
17
12
7
2
0
200 400 600 800 1000
ILOAD (mA)
8040 G17
LED Current vs Adjust Voltage
1200
1000
800
600
400
200
0
0 200 400 600 800 1000 1200
ADJUST VOLTAGE
8040 G19
PIN FUNCTIONS
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 VIN if the SHDN function is unused.
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 VIN)
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
8040p
5
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