LT3513 LINER [Linear Technology], LT3513 Datasheet - Page 8

• Manufacturer Part Number: LT3513
• Description: 2MHz High Current 5-Output Regulator for TFT-LCD Panels
• Manufacturer: LINER [Linear Technology]

PIN FUNCTIONS
LT3513
PGOOD (Pin 11): Power Good Comparator Output. This is
the open collector output of the power good comparator
and can be used in conjunction with an external P-chan-
nel MOSFET to provide output disconnect for AV
shown in Figure 2. When switcher 2’s output reaches
approximately 90% of its programmed voltage, PGOOD
will be pulled to ground. This will pull down on the gate
of the MOSFET, connecting AV
between the source and the gate of the P-channel MOSFET
keeps it off when switcher 2’s output is low.
V
Internal Error Amplifi er. Connect a series RC from this pin
to ground to compensate switching regulator 3.
C
the V
feedback pins reaching 1.125V to V
capacitor value can be set using the equation C = (20μA
• t
GND (Pins 14, 17, 33): Ground.
SW2 (Pins 15, 16): Switch Node. The SW2 pin is the col-
lector of the internal NPN bipolar transistor for switching
regulator 2. Minimize trace area at this pin to keep EMI
down.
BIAS (Pins 18, 29): The BIAS pin is used to improve ef-
fi ciency when operating at higher input voltages. Connect-
ing this pin to the output of switching regulator 1 forces
most of the internal circuitry to draw its operating current
from V
4 and 5 are supplied by BIAS. Switches 2, 3, 4 and 5 will
not switch until the BIAS pin reaches approximately 2.7V.
Both BIAS pins must be tied to V
FB2 (Pin 19): Feedback Pin. Tie the resistor divider tap
to this pin and set AV
(1 + R5/R6). Reference designators refer to Figure 2.
V
Internal Error Amplifi er. Connect a series RC from this pin
to ground to compensate switching regulator 2.
8
C3
T
C2
DELAY
(Pin 13): Timing Capacitor Pin. This is the input to
(Pin 12): Control Voltage and Compensation Pin for
(Pin 20): Control Voltage and Compensation Pin for
ON
LOGIC
)/1.1V.
timer and programs the time delay from all four
rather than V
DD
IN
according to AV
. The drivers of switches 2, 3,
DD
. A 100k pull-up resistor
LOGIC
ON
turning on. The C
.
DD
= 1.23V •
DD
as
T
V
Internal Error Amplifi er. Connect a series RC from this pin
to ground to compensate switching regulator 4.
RUN-SS1 (Pin 22): Run/Soft-Start Pin. This is the soft-start
pin for switching regulator 1. Place a soft-start capacitor
here to limit start-up inrush current and output voltage
ramp rate. When power is applied to the V
current source charges the capacitor. When the voltage
at this pin reaches 0.8V, switch 1 turns on and begins
switching. For slower start-up use a larger capacitor. For
complete shutdown tie RUN-SS1 to ground.
NFB4 (Pin 23): Negative Feedback Pin. Tie the resistor di-
vider tap to this pin and set V
(1 + R3/R4). Reference designators refer to Figure 2.
D4 (Pin 24): Internal Schottky Diode Pin. This pin is the
anode of an internal Schottky diode with the other end
connected to ground. This Schottky diode is used in
generating the V
SW4 (Pin 25): Switch Node. The SW4 pin is the collector of
the internal NPN bipolar transistor for switching regulator
4. Minimize trace area at this pin to keep EMI down.
BD (Note 26): NPN LDO Base Drive. This pin controls the
base of the external NPN LDO transistor.
LDOPWR (Pin 27): Input Voltage for LDO Driver. This pin
supplies the current for the NPN LDO base. This pin can be
connected to V
pin can alternatively be connected to the AV
BOOST (Pin 28): The BOOST pin is used to provide a
drive voltage higher than V
An internal Schottky diode is connected between BIAS
and BOOST. A capacitor needs to be connected between
BOOST and SW1.
SENSE
(along with the SENSE
current for the buck switching regulator.
C4
(Pin 21): Control Voltage and Compensation Pin for
–
(Pin 30) Negative Current Sense Input. This pin
IN
OFF
. To save power at high V
output.
+
pin) is used to sense the inductor
IN
OFF
to the switch 1 drive circuit.
according to V
IN
IN
voltages, the
DD
OFF
pin, a 2μA
supply.
= –1.18 •
3513fa