LTC1142-ADJ Linear Technology, LTC1142-ADJ Datasheet - Page 6

• Manufacturer Part Number: LTC1142-ADJ
• Description: Dual High Efficiency Synchronous Step-Down Switching Regulators
• Manufacturer: Linear Technology

PI FU CTIO S
LTC1142/LTC1142L/LTC1142HV
NC (Pins 7, 8): No Connection.
PDRIVE 5 (Pin 9): High Current Drive for Top P-Channel
MOSFET, 5V Section. Voltage swing at this pin is from V
to ground.
V
decoupled to 5V power ground Pin 18.
C
sets the operating frequency for the 5V section. (The actual
frequency is also dependent upon the input voltage.)
INT V
section, nominally 3.3V, can be decoupled to signal ground,
Pin 17. Do not externally load this pin.
I
tion. The 5V section current comparator threshold in-
creases with the Pin 13 voltage.
SENSE
which sets the output voltage for the 5V section. Pin 14 is
also the (–) input for the current comparator on the
5V section.
SENSE
Comparator. A built-in offset between Pins 15 and 14 in
conjunction with R
for the 5V section.
SHUTDOWN 5 (Pin 16): When grounded, the 5V section
operates normally. Pulling Pin 16 high holds both MOSFETs
off and puts the 5V section in micropower shutdown
mode. Requires CMOS logic signal with t
“float” Pin 16.
SGND5 (Pin 17): The 5V section small-signal ground must
be routed separately from other grounds to the (–) termi-
nal of the 5V section output capacitor.
PGND5 (Pin 18): The 5V section driver power ground
connects to source of N-channel MOSFET and the (–)
terminal of the 5V section input capacitor.
NC (Pin 19): No Connection.
NDRIVE 5 (Pin 20): High Current Drive for Bottom
N-Channel MOSFET, 5V Section. Voltage swing at Pin 20
is from ground to V
NC (Pins 21, 22): No Connection.
6
TH5
IN5
T5
U
(Pin 11): External capacitor C
(Pin 13): Gain Amplifier Decoupling Point, 5V Sec-
(Pin 10): Supply pin, 5V section, must be closely
CC5
–
+
5 (Pin 15): The (+) Input to the 5V Section Current
5 (Pin 14): Connects to internal resistive divider
(Pin 12) : Internal supply voltage for the 5V
U
SENSE5
IN5
U
.
sets the current trip threshold
T5
from Pin 11 to ground
r
, t
f
< 1 s. Do not
IN5
PDRIVE 3 (Pin 23): High Current Drive for Top P-Channel
MOSFET, 3.3V Section. Voltage swing at this pin is from
V
V
decoupled to 3.3V power ground, Pin 4.
C
sets the operating frequency for the 3.3V section. (The
actual frequency is also dependent upon the input voltage.)
INT V
section, nominally 3.3V, can be decoupled to signal ground,
Pin 3. Do not externally load this pin.
I
Section. The 3.3V section current comparator threshold
increases with the Pin 27 voltage.
SENSE
which sets the output voltage for the 3.3V section. Pin 28
is also the (–) input for the current comparator on the
3.3V section.
LTC1142HV-ADJ/LTC1142L-ADJ
SENSE
Comparator. A built-in offset between Pins 1 and 28 in
conjunction with R
for this section.
V
external resistive divider used to set the output voltage for
section 1.
SHUTDOWN 1 (Pin 3): When grounded, the section 1
regulator operates normally. Pulling Pin 3 high holds both
MOSFETs off and puts this section in micropower shut-
down mode. Requires CMOS logic signal with t
Do not “float” Pin 3.
SGND1 (Pin 4): The section 1 small-signal ground must
be routed separately from other grounds to the (–) termi-
nal of the section 1 output capacitor.
PGND1 (Pin 5): The section 1 driver power ground con-
nects to source of N-channel MOSFET and the (–) terminal
of the section 1 input capacitor.
TH3
IN3
IN3
T3
FB1
(Pin 25): External capacitor C
to ground.
(Pin 24): Supply pin, 3.3V section, must be closely
(Pin 27): Gain Amplifier Decoupling Point, 3.3V
(Pin 2): This pin serves as the feedback pin from an
CC3
–
+
1 (Pin 1): The (+) Input to the Section 1 Current
3 (Pin 28): Connects to internal resistive divider
(Pin 26): Internal supply voltage for the 3.3V
SENSE1
sets the current trip threshold
T3
from Pin 25 to ground
r
, t
f
< 1 s.