LTC3534 Ver la hoja de datos (PDF) - Linear Technology
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LTC3534 Datasheet PDF : 20 Pages
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LTC3534
Pin Functions
GND Pads (Pins 1, 8, 9, 16; GN Package): IC Substrate
Grounds. These pins MUST be soldered to the printed
circuit board ground to provide both electrical contact
and a good thermal contact to the PCB.
RUN/SS (Pin 2): Combined Shutdown and Soft-Start. Ap-
plying a voltage below 400mV shuts down the IC. Apply
a voltage above 1.4V to enable the IC and above 2.4V to
ensure that the error amp is not clamped from soft-start.
An R-C from the enable command signal to this pin will
provide a soft-start function by limiting the rise time of
the VC pin. PWM mode operation must be commanded
to properly enable the IC.
GND (Pin 3): Signal Ground for the IC.
PGND1, PGND2 (Pins 4, 7): Power Ground for the Internal
N-channel MOSFET Power Switches (Switches B and C).
SW1 (Pin 5): Switch Pin where Internal Switches A and
B are Connected. Connect inductor from SW1 to SW2.
Minimize trace length to reduce EMI.
SW2 (Pin 6): Switch Pin where Internal Switches C and
D are Connected. Minimize trace length to reduce EMI.
PWM (Pin 10): Burst Mode Select. PWM must be driven
HIGH during start-up. When VOUT is in regulation, the
PWM pin may be driven LOW to command Burst Mode
operation. Applying a voltage below 400mV enables Burst
Mode operation, providing a significant efficiency improve-
ment at light loads. Burst Mode operation will continue
until this pin is driven high. Applying a voltage above 1.4V
disables Burst Mode operation, enabling low noise, fixed
frequency operation.
VOUT (Pin 11): Output of the Synchronous Rectifier. A filter
capacitor is placed from VOUT to GND. A ceramic bypass
capacitor is recommended as close to the VOUT and GND
pins as possible. VOUT is given by the following equation:
VOUT
=
1.000
•
R1+ R2
R2
V
PVIN (Pin 12): Power VIN Supply Pin. A 10µF ceramic
capacitor is recommended as close to the PVIN and PGND
pins as possible.
VIN (Pin 13): Input Supply Pin. Connect the power source
to this pin.
VC (Pin 14): Error Amp Output. An R-C network is con-
nected from this pin to FB for loop compensation. Refer
to “Closing the Feedback Loop” section for component
selection guidelines.
FB (Pin 15): Feedback Pin. Connect VOUT resistor divider
tap to this pin. The output voltage can be adjusted from
1.8V to 7V. The feedback reference voltage is typically 1V.
Exposed Pad (Pin 17; DHC Package): IC Substrate Ground.
This pin MUST be soldered to the printed circuit board
ground to provide both electrical contact and a good
thermal contact to the PCB.
For more information www.linear.com/LTC3534
3534fb
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