LTC3609EWKG#PBF Linear Technology, LTC3609EWKG#PBF Datasheet - Page 12

• Manufacturer Part Number: LTC3609EWKG#PBF
• Description: IC DC/DC CONV STP-DWN 6A 52-QFN
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC3609EWKG#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.6 ~ 36 V
• Current - Output: 6A
• Voltage - Input: 4 ~ 32 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 52-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Frequency - Switching: -

LTC3609
applicaTions inForMaTion
Because the voltage at the I
rent into this pin is not exactly inversely proportional to
V
To correct for this error, an additional resistor R
nected from the I
stabilize the frequency.
Changes in the load current magnitude will also cause
frequency shift. Parasitic resistance in the MOSFET
switches and inductor reduce the effective voltage across
the inductance, resulting in increased duty cycle as the

IN
R
, especially in applications with lower input voltages.
ON
2
=
0 7
5
.
V
V
ON
R
ON
pin to the 5V INTV
ON
pin is about 0.7V, the cur-
Figure 1b. Switching Frequency vs R
CC
Figure 1a. Switching Frequency vs R
supply will further
1000
1000
100
100
100
100
V
ON2
OUT
V
OUT
= 3.3V
= 1.5V
con-
R
R
ON
ON
1000
1000
(k )
(k )
V
load current increases. By lengthening the on-time slightly
as current increases, constant frequency operation can be
maintained. This is accomplished with a resistive divider
from the I
required will depend on the parasitic resistances in the
specific application. A good starting point is to feed about
25% of the voltage change at the I
as shown in Figure 2a. Place capacitance on the V
to filter out the I
The resistor load on I
amp and degrades load regulation, which can be avoided
by using the PNP emitter follower of Figure 2b.
V
OUT
OUT
V
V
OUT
= 3.3V
OUT
= 12V
= 5V
= 2.5V
ON
ON
(V
3609 F01a
3609 F01b
(V
TH
ON
10000
10000
ON
= INTV
pin to the V
= 0V)
TH
variations at the switching frequency.
CC
)
TH
reduces the DC gain of the error
ON
pin and V
TH
pin to the V
OUT
. The values
ON
ON
3609fb
pin
pin