LT3743IFE#PBF Linear Technology, LT3743IFE#PBF Datasheet - Page 15

• Manufacturer Part Number: LT3743IFE#PBF
• Description: IC LED DVR HP CONST CURR 28TSSOP
• Manufacturer: Linear Technology
• Type: High Power, Constant Currentr

Specifications of LT3743IFE#PBF

• Topology: High Side, Low Side, PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: General Purpose
• Type - Secondary: RGB
• Frequency: 200kHz ~ 1MHz
• Voltage - Supply: 6 V ~ 36 V
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• Operating Temperature: -40°C ~ 125°C
• Internal Switch(s): Yes
• Efficiency: 92%
• Led Driver Application: Lighting
• No. Of Outputs: 1
• Output Current: 20A
• Output Voltage: 40V
• Input Voltage: 6V To 36V
• Dimming Control Type: PWM
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Current - Output / Channel: -

APPLICATIONS INFORMATION
Whenever possible, utilize a switching MOSFET that
minimizes the total gate charge to limit the internal power
dissipation of the LT3743.
Table 3. Recommended Switching FETs
Input Capacitor Selection
The input capacitor should be sized at 4μF for every 1A
of output current and placed very close to the high side
MOSFET. A small 1μF ceramic capacitor should be placed
near the V
noise immunity. The input capacitor should have a ripple
current rating equal to half of the maximum output current.
It is recommended that several low ESR ceramic capacitors
V
(V)
24
24
12
36
24
8
IN
V
2-4
2-4
(V)
OUT
4
4
4
4
5-10 RJK0365DPA RJK0330DPB Renesas
(A)
20
10
20
40
I
IN
5
D
Figure 4a. Power Loss Example for M1
7
6
4
2
1
0
5
3
0
and ground pins of the LT3743 for optimal
RJK0368DPA RJK0332DPB
RJK0365DPA RJK0346DPA
FDMS8680
Si7884BDP
PSMN4R0-
TOP FET
30YL
10
INPUT VOLTAGE (V)
TOTAL
FDMS8672AS Fairchild
BOTTOM FET MANUFACTURER
RJK0346DPA NXP/Philips
20
SiR470DP
OHMIC
TRANSITIONAL
30
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Vishay
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3743 F04a
40
Figure 4
be used as the input capacitance. Use only type X5R or
X7R capacitors as they maintain their capacitance over a
wide range of operating voltages and temperatures.
Output Capacitor Selection
The output capacitors need to have very low ESR (equivalent
series resistance) to allow the LED current to ramp quickly.
A minimum of 50μF/A of load current should be used in
most designs. The capacitors also need to be surge rated
to the maximum output current. To achieve the lowest
possible ESR, several low ESR capacitors should be used
in parallel. Many applications benefi t from the use of high
density POSCAP capacitors, which are easily destroyed
when exposed to overvoltage conditions. To prevent this,
select POSCAP capacitors that have a voltage rating that
is at least 50% higher than the regulated voltage
C
The C
more than 50nF to ensure proper operation of the LT3743.
Use 220nF for high current switching MOSFETs with high
gate charge.
BOOT
BOOT
Capacitor Selection
2.5
2.0
1.5
1.0
0.5
capacitor must be sized less than 220nF and
Figure 4b. Power Loss Example for M2
0
0
10
INPUT VOLTAGE (V)
TOTAL
20
TRANSITIONAL
OHMIC
30
3743 F04b
40
LT3743
15
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