Datasheet

LT3464
5
3464f
CTRL (Pin 1): Internal Reference Override Pin. This allows
the FB voltage to be externally set between 0V and 1.25V.
Tie this pin to above 1.5V (V
IN
for example) to use the
internal 1.25V reference.
VV
R
R
OUT CTRL
=+






2
1
1
when V
CTRL
is less than 1.25V (see Figure 4)
FB (Pin 2): Feedback Pin. The LT3464 regulates its feed-
back pin to 1.25V if the internal reference is used or to
V
CTRL
if the CTRL pin is between 0V and 1.25V. Connect
the feedback resistor divider tap to this pin. Set the output
voltage by selecting R1 and R2 (see Figure 4).
RR
V
V
OUT
REF
21 1=






–
OUT (Pin 3): PNP Collector. This is the output of the
Output Disconnect circuit. Bypass this pin with at least a
0.1µF capacitor connected to the CAP pin or to ground.
GND (Pin 4): Ground. Tie this pin directly to the ground
plane.
CAP (Pin 5): PNP Emitter and Schottky Cathode. This pin
connects to the output capacitor, and optionally to the
external phase-lead capacitor.
SW (Pin 6): Switch Pin and Schottky Anode. This is the
collector of the internal NPN power switch. Minimize the
metal trace area connected to the pin to minimize EMI.
V
IN
(Pin 7): Input Supply Pin: Bypass this pin with a
capacitor located as close to the device as possible.
SHDN (Pin 8): Shutdown Pin. This pin is used to put the
device in shutdown mode. Tie the pin low to shut down the
LT3464. Tie high for normal operation See the electrical
specifications for the required voltages.
UU
U
PI FU CTIO S
FB Pin Voltage vs
CTRL Pin Voltage
FB and CTRL Pin
Bias Currents
TYPICAL PERFOR A CE CHARACTERISTICS
UW
HYSTERESIS (mV)
12
10
8
6
4
2
0
3464 G19
TEMPERATURE (°C)
–50
–25
0 25 50 75 100
TEMPERATURE (°C)
–50
–25
0 25 50 75 100
BIAS CURRENT (nA)
3464 G18
8
7
6
5
4
3
2
1
0
CTRL PIN
FEEDBACK PIN
FB PIN VOLTAGE (V)
1.50
1.25
1.00
0.75
0.50
0.25
0
3464 G17
CONTROL PIN VOLTAGE (V)
0
0.25
0.5 0.75 1.0 1.25 1.5 1.75
FB Pin Hysteresis