LTM8040EV#PBF Linear Technology, LTM8040EV#PBF Datasheet - Page 10

• Manufacturer Part Number: LTM8040EV#PBF
• Description: IC LED DRVR HP CONST CURR 66-LGA
• Manufacturer: Linear Technology
• Series: µModuler

Specifications of LTM8040EV#PBF

• Design Resources: LTM8040 Spice Model
• Voltage - Input: 4 ~ 36 V
• Voltage - Output: 2.5 ~ 13 V
• Current - Output: 1A
• Power (watts): 13W
• Mounting Type: Surface Mount
• Termination Style: Surface Mount (SMD,SMT)
• Size / Dimension: 0.59" L x 0.35" W x 0.17" H (15mm x 9mm x 4.32mm)
• Operating Temperature: 0°C ~ 125°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTM8040
APPLICATION INFORMATION
If another frequency is desired, Table 1 shows suggested
R
Table 1. R
10
T
Figure 2a. Tie BIAS to LPWR if LPWR is Greater Than 2.6V
selections for a variety of switching frequencies.
4V TO 36V
V
T
IN
vs Frequency
R
OPEN
T
18.7
24.9
29.4
35.7
54.9
88.7
137
174
215
487
13
16
75
(kΩ)
C1
2.2μF
LTM8040
V
SHDN
ADJ
PWM
RT
IN
GND
Figure 2c. Tie BIAS to an External Power Source if Neither V
Nor LPWR are Suitable
4V TO 36V
LPWR
LEDA
BIAS
FREQUENCY (MHz)
V
IN
2.00
1.84
1.70
1.50
1.37
1.25
1.00
0.90
0.85
0.75
0.68
0.65
0.57
0.50
3.3V
C1
2.2μF
8040 F02a
WHITE
LED
LTM8040
V
SHDN
ADJ
PWM
RT
IN
GND
BIAS Pin Considerations
For proper operation, the BIAS pin must be powered by
at least 2.6V. Figure 2 shows three ways to arrange the
circuit. For outputs of 2.6V or higher, the standard circuit
(Figure 2a) is recommended. For output voltages below
2.6V, the BIAS pin can be tied to the input (Figure 2b) at
the cost of some effi ciency. Finally, the BIAS pin can be
tied to another source that is at least 2.6V (Figure 2c).
For example, if a 3.3V source is on whenever the LED is
on, the BIAS pin can be connected to the 3.3V output. In
all cases, be sure that the maximum voltage at the BIAS
pin is both less than 25V and the sum of V
less than 51V. If BIAS is powered by a source other than
LPWR, a local decoupling capacitor may be necessary.
The value of the decoupling capacitor is dependent upon
the source and PCB layout.
LPWR
LEDA
BIAS
Figure 2b. BIAS May be Tied to V
5.5V
V
IN
1μF
C1
2.2μF
2.5V
8040 F02c
3.3V
RED
LED
LTM8040
IN
V
SHDN
ADJ
PWM
RT
IN
GND
LPWR
IN
LEDA
BIAS
if LPWR is Below 2.6V
IN
2.5V
and BIAS is
8040 F02b
RED
LED
8040fa