LTC1142L_15 Datasheet, PDF (6/20 Pages) Linear Technology – Dual High Efficiency Synchronous Step-Down Switching Regulators

LTC1142/LTC1142L/LTC1142HV
PI FU CTIO S
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_IN5
to ground.
V_IN5 (Pin 10): Supply pin, 5V section, must be closely
decoupled to 5V power ground Pin 18.
C_T5 (Pin 11): External capacitor C_T5 from Pin 11 to ground
sets the operating frequency for the 5V section. (The actual
frequency is also dependent upon the input voltage.)
INTV_CC5 (Pin 12) : Internal supply voltage for the 5V
section, nominally 3.3V, can be decoupled to signal ground,
Pin 17. Do not externally load this pin.
I_TH5 (Pin 13): Gain Amplifier Decoupling Point, 5V Sec-
tion. The 5V section current comparator threshold in-
creases with the Pin 13 voltage.
SENSE^– 5 (Pin 14): Connects to internal resistive divider
which sets the output voltage for the 5V section. Pin 14 is
also the (–) input for the current comparator on the
5V section.
SENSE⁺5 (Pin 15): The (+) Input to the 5V Section Current
Comparator. A built-in offset between Pins 15 and 14 in
conjunction with R_SENSE5 sets the current trip threshold
for the 5V section.
SHDN5 (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_r, t_f < 1µs. Do not “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_IN5.
NC (Pins 21, 22): No Connection.
PDRIVE 3 (Pin 23): High Current Drive for Top P-Channel
MOSFET, 3.3V Section. Voltage swing at this pin is from
V_IN3 to ground.
V_IN3 (Pin 24): Supply pin, 3.3V section, must be closely
decoupled to 3.3V power ground, Pin 4.
C_T3 (Pin 25): External capacitor C_T3 from Pin 25 to ground
sets the operating frequency for the 3.3V section. (The
actual frequency is also dependent upon the input voltage.)
INTV_CC3 (Pin 26): Internal supply voltage for the 3.3V
section, nominally 3.3V, can be decoupled to signal ground,
Pin 3. Do not externally load this pin.
I_TH3 (Pin 27): Gain Amplifier Decoupling Point, 3.3V
Section. The 3.3V section current comparator threshold
increases with the Pin 27 voltage.
SENSE ^– 3 (Pin 28): Connects to internal resistive divider
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⁺1 (Pin 1): The (+) Input to the Section 1 Current
Comparator. A built-in offset between Pins 1 and 28 in
conjunction with R_SENSE1 sets the current trip threshold
for this section.
V_FB1 (Pin 2): This pin serves as the feedback pin from an
external resistive divider used to set the output voltage for
section 1.
SHDN1 (Pin 3): When grounded, the section 1 regulator
operates normally. Pulling Pin 3 high holds both MOSFETs
off and puts this section in micropower shutdown mode.
Requires CMOS logic signal with t_r, t_f < 1µs. 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.
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