Datasheet

LTC3562
7
3562fa
PIN FUNCTIONS
AGND (Pin 1): Analog Ground Pin. All small-signal com-
ponents should connect to this ground, which in turn
connects to PGND at one point.
FB400A (Pin 2): Feedback Pin for R400A. When the con-
trol loop is complete, this pin servos to 1 of 16 possible
set-points based on the programmed value from the I
2
C
serial port (see Table 4).
OUT400B (Pin 3): Output Voltage Feedback Pin for
R400B. An I
2
C programmable internal resistor divider
divides the output voltage down for comparison to the
internal reference voltage. This pin converges to 1 of
128 possible set-points based on the programmed value
from the I
2
C serial port (see Tables 5 and 6). This node
must be bypassed to GND with a 10μF or greater ceramic
capacitor.
SW400B (Pin 4): Switch Node Connection to the Inductor
for R400B. This pin connects to the drains of the internal
power MOSFET switches of R400B.
PGND (Pins 5, 11): Power Ground Pin. Connect this pin
closely to the (–) terminal of C
IN
.
SW400A (Pin 6): Switch Node Connection to the Inductor
for R400A. This pin connects to the drains of the internal
power MOSFET switches of R400A.
V
IN
(Pins 7, 8, 9): Input Supply Pin. This pin must be
closely decoupled to GND with a 10μF or greater ceramic
capacitor.
SW600A (Pin 10): Switch Node Connection to the Inductor
for R600A. This pin connects to the drains of the internal
power MOSFET switches of R600A.
SW600B (Pin 12): Switch Node Connection to the Inductor
for R600B. This pin connects to the drains of the internal
power MOSFET switches of R600B.
OUT600B (Pin 13): Output Voltage Feedback Pin for
R600B. An I
2
C programmable internal resistor divider
divides the output voltage down for comparison to the
internal reference voltage. This pin converges to 1 of
128 possible set-points based on the programmed value
from the I
2
C serial port (see Tables 5 and 6). This node
must be bypassed to GND with a 10μF or greater ceramic
capacitor.
FB600A (Pin 14): Feedback Pin for R600A. When the con-
trol loop is complete, this pin servos to 1 of 16 possible
set-points based on the programmed value from the I
2
C
serial port (see Table 4).
POR600A (Pin 15): Power-On Reset for R600A. This open-
drain output goes high impedance after a 230ms delay
after the output of R600A reaches 92% of its regulation
voltage. This output gets pulled to GND whenever R600A
falls below 92% of its regulation voltage.
RUN400A (Pin 16): Enable Pin for R400A, Active High.
Apply a voltage greater than 1V to enable this regulator.
RUN600A (Pin 17): Enable Pin for R600A, Active Low.
Apply a voltage less than 0.3V to enable this regulator.
DV
CC
(Pin 18): Supply Voltage for I
2
C Lines. This pin sets the
logic reference level of the LTC3562. A UVLO circuit on the
DV
CC
pin forces all registers to a default setting whenever
DV
CC
is < 1V. Bypass to GND with a 0.1μF capacitor.
SCL (Pin 19): I
2
C Clock Input. Serial data is shifted one
bit per clock to control the LTC3562. The logic level for
SCL is referenced to DV
CC
.
SDA (Pin 20): I
2
C Data Input. The logic level for SDA is
referenced to DV
CC
.
Exposed Pad (Pin 21): Ground. Must be soldered to
PCB ground for electrical contact and optimum thermal
performance.