LT3433 LINER [Linear Technology], LT3433 Datasheet - Page 6

• Manufacturer Part Number: LT3433
• Description: High Voltage Step-Up/Step-Down DC/DC Converter
• Manufacturer: LINER [Linear Technology]

LT3433
PI FU CTIO S
The time from V
be calculated given a capacitor C
SHDN (Pin 11): Shutdown. If the SHDN pin is externally
pulled below 0.5V, low current shutdown mode is initiated.
During shutdown mode, all internal functions are disabled,
and I
a digital input, however, there is a small amount of input
hysteresis built into the SHDN circuit to help assure glitch-
free mode switching. If shutdown is not desired, connect
the SHDN pin to V
V
circuitry is powered from this supply, which is internally
regulated to 2.5V through an on-board linear regulator.
Current drive for this regulator is sourced from the V
The V
The V
above the regulated voltage allows the use of external power
for much of the LT3433 circuitry. When using external drive,
6
BIAS
t
U
SS
CC
BIAS
(Pin 12): Internal Local Supply. Much of the LT3433
BIAS
= (2.7 • 10
is reduced to 10 A. This pin is intended to receive
supply only sources current, so forcing this pin
U
supply is short-circuit protected to 5mA.
SS
5
)C
= 0V to maximum available current can
IN
U
.
SS
or 0.27s/ F
SS
as:
IN
pin.
this pin should be driven above 3V to assure the internal
supply is completely disabled. This pin is typically diode-
connected to the converter output to maximize conversion
efficiency. This pin must be bypassed with at least a 0.1 F
ceramic capacitor to SGND.
V
compared with the voltage on V
operation in single or 2-switch mode. When the ratios of
the two voltages are such that a >75% duty cycle is required
for regulation, the low side switch is enabled. Drive bias for
the low side switch is also derived directly from this pin.
PWRGND (Pin 14): High Current Ground Reference. This
is the current return for the low side switch and corresponds
to the emitter of the low side switch transistor.
SW_L (Pin 15): Ground Referenced Switch Output. This pin
is the collector of the low side switch transistor. The low
side switch shorts the SW_L pin to PWRGND when enabled.
The series impedance of the ground-referenced switch is
0.6 .
OUT
(Pin 13): Converter Output Pin. This pin voltage is
IN
internally to control
3433ia