LTC3609EWKG#PBF Linear Technology, LTC3609EWKG#PBF Datasheet - Page 15

• 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: -

applicaTions inForMaTion
with changes in V
threshold forces continuous synchronous operation, al-
lowing current to reverse at light loads and maintaining
high frequency operation.
In addition to providing a logic input to force continuous
operation, the FCB pin provides a means to maintain a
flyback winding output when the primary is operating
in discontinuous mode. The secondary output V
normally set as shown in Figure 4 by the turns ratio N
of the transformer. However, if the controller goes into
discontinuous mode and halts switching due to a light
primary load current, then V
resistor divider from V
voltage V
forced until V
V
OUT2(MIN)
V
OUT2(MIN)
OUT1
C
OUT
C
V
OUT2
1µF
SEC
OUT2
= 0.6V 1+
+
+
IN
has risen above its minimum:
below which continuous operation is
. Tying the FCB pin below the 0.6V



IN4148
OUT2
C
1:N
R4
R3
T1
IN
to the FCB pin sets a minimum
+
OUT2



V
IN
GND
will droop. An external
41
42
43
44
45
46
47
48
49
50
51
52
Figure 4. Secondary Output Loop and EXTV
SW
SW
SW
SW
SW
SW
SW
PV
PV
PV
PV
PV
IN
IN
IN
IN
IN
40 39 38 37 36 35 34 33 32 31 30 29 28 27
1
2
3
4
OUT2
5
6
is
LTC3609
7
8
SW
SW
Fault Conditions: Current Limit and Foldback
The LTC3609 has a current mode controller which inher-
ently limits the cycle-by-cycle inductor current not only
in steady-state operation but also in transient. To further
limit current in the event of a short circuit to ground, the
LTC3609 includes foldback current limiting. If the output
falls by more than 25%, then the maximum sense voltage is
progressively lowered to about one sixth of its full value.
INTV
An internal P-channel low dropout regulator produces the
5V supply that powers the drivers and internal circuitry
within the LTC3609. The INTV
RMS and must be bypassed to ground with a minimum of
4.7µF tantalum or ceramic capacitor. Good bypassing is
necessary to supply the high transient currents required
by the MOSFET gate drivers.
9 10 11 12 13 14
CC
Regulator and EXTV
CC
Connection
PGOOD
SGND
SGND
SGND
SGND
V
RNG
FCB
V
I
I
NC
NC
NC
ON
TH
FB
26
25
24
23
22
21
20
19
18
17
16
15
3609 F04
CC
CC
Connection
pin can supply up to 50mA
R4
R3
OPTIONAL EXTV
CONNECTION
5V < V
OUT2
LTC3609
< 7V
CC

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