lt3750 Linear Technology Corporation, lt3750 Datasheet - Page 7

• Manufacturer Part Number: lt3750
• Description: Capacitor Charger Controller
• Manufacturer: Linear Technology Corporation

OPERATIO
a rate (V
rored on the secondary winding –N • (V
which reverse biases the diode and prevents current flow
in the secondary winding. Thus, energy is stored in the
core of the transformer.
3. Secondary Energy Transfer
When current limit is reached, the current limit compara-
tor resets the NMOS on-latch and the device enters the
third phase of operation, secondary energy transfer. The
energy stored in the transformer core forward biases the
diode and current flows into the output capacitor. During
this time, the output voltage (neglecting the diode drop) is
reflected back to the primary coil. If the target output
TRANS
– V
U
DS(ON)
)/L
PRI
. The input voltage is mir-
TRANS
– V
DS(ON)
)
voltage is reached, the V
latch and the DONE pin goes low. Otherwise, the device
enters the next phase of operation.
4. Discontinuous Mode Detection
Once all the current is transferred to the output capacitor,
(V
A transformer with no energy cannot support a DC voltage,
so, the voltage across the primary will decay to zero. In
other words, the drain of the NMOS will ring down from
V
voltage falls to V
the NMOS on-latch and a new charge cycle begins. Steps
2-4 continue until the target output voltage is reached.
TRANS
OUT
+ V
+ (V
DIODE
OUT
)/N will appear across the primary winding.
TRANS
+ V
DIODE
+ 36mV, the DCM comparator sets
OUT
)/N to V
comparator resets the master
TRANS
. When the drain
LT3750
3750fa
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