LT3485 Просмотр технического описания (PDF) - Linear Technology
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LT3485
Linear Technology
LT3485 Datasheet PDF : 20 Pages
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LT3485-0/LT3485-1/
LT3485-2/LT3485-3
PI FU CTIO S
CHARGE (Pin 1): Charge Pin. A low (<0.3V) to high (>1V)
transition on this pin puts the part into power delivery
mode. Once the target voltage is reached, the part will stop
charging the output. Toggle this pin to start charging
again. Bringing the pin low (<0.3V) will terminate the
power delivery and put the part in shutdown.
VBAT (Pin 2): Battery Supply Pin. Must be locally bypassed
with a good quality ceramic capacitor. Battery supply
must be 1.7V or higher.
VIN (Pin 3): Input Supply Pin. Must be locally bypassed
with a good quality ceramic capacitor. Input supply must
be 2.5V or higher.
SW (Pins 4, 5): Switch Pin. This is the collector of the
internal NPN power switch. Minimize the metal trace area
connected to this pin to minimize EMI. Tie one side of the
primary of the transformer to this pin. The target output
voltage is set by the turns ratio of the transformer.
Choose Turns Ratio N by the following equation:
IGBTOUT (Pin 6): Output Drive for IGBT Gate. Connect
this pin to the gate of the IGBT.
IGBTIN (Pin 7): Logic Input Pin for IGBT Drive. When this
pin is driven higher than 1.5V, the IGBT output pin goes
high. When the pin is below 0.3V, the output is low.
IGBTPWR (Pin 8): Input Supply Pin. Must be locally
bypassed with a good quality ceramic capacitor. Input
supply must be 0.1V higher than the turn-on voltage for
the IGBT.
DONE (Pin 9): Open NPN Collector Indication Pin. When
target output voltage is reached, NPN turns on. This pin
needs a pull-up resistor or current source.
VMONT (Pin 10): Supplies a voltage proportional to the
output voltage where 1V is the end of charge voltage. Only
valid while the part is charging.
Exposed Pad (Pin 11): Ground. Tie directly to local
ground plane.
N = VOUT + 2
31.5
where VOUT is the desired output voltage.
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