ltc1876eg-trpbf Linear Technology Corporation, ltc1876eg-trpbf Datasheet - Page 8

• Manufacturer Part Number: ltc1876eg-trpbf
• Description: High Efficiency, 2-phase, Dual Synchronous Step-down Switching Controller And Step-up Regulator
• Manufacturer: Linear Technology Corporation

PIN
LTC1876
RUN/SS1, RUN/SS2 (Pins 1, 23): Combination of Soft-Start,
Run Control Inputs and Short-Circuit Detection Timers. A
capacitor to ground at each of these pins sets the ramp time
to full output current. Forcing either of these pins back below
1V causes the IC to shut down the circuitry required for that
particular controller. Latchoff overcurrent protection is also
invoked via this pin as described in the Applications Informa-
tion section.
SENSE1
Differential Current Comparator. The I
controlled offsets between the SENSE
conjunction with R
TYPICAL PERFOR A CE CHARACTERISTICS
200mV/DIV
8
10V/DIV
10V/DIV
2A/DIV
U
V
V
SW1
SW2
V
I
IN
IN
FUNCTIONS
V
V
I
+
Input Source/Capacitor
Instantaneous Current (Figure 1)
OUT5
, SENSE2
IN
OUT
= 15V
U
= 5V
= I
OUT3.3
20mV/DIV
0.5A/DIV
= 2A
V
SENSE
I
+
OUT
OUT
1 s/DIV
(Pins 2, 14): The (+) Input to each
U
V
V
V
I
Burst Mode Operation (Figure 1)
OUT
IN
OUT
FCB
set the current trip threshold.
= 15V
= 20mA
= OPEN
= 5V
W
U
10 s/DIV
1876 G31
–
and SENSE
TH
200mV/DIV
pin voltage and
2A/DIV
V
I
OUT
OUT
Load Step (Figure 1)
V
V
LOAD STEP = 0A TO 3A
CONTINUOUS MODE
1876 G32
+
IN
OUT
pins in
= 15V
= 5V
SENSE1
Differential Current Comparators.
V
sensed feedback voltage for each controller from an external
resistive divider across the output.
FREQSET (Pin 5): Frequency Control Input to the Oscillator.
This pin can be left open, tied to ground, tied to INTV
driven by an external voltage source. This pin can also be used
with an external phase detector to build a true phase-locked
loop.
STBYMD (Pin 6): Control pin that determines which circuitry
remains active when the controllers are shut down and/or
OSENSE1
20mV/DIV
0.5A/DIV
–
V
, SENSE2
, V
I
OUT
OUT
OSENSE2
Constant Frequency (Burst
Inhibit) Operation (Figure 1)
V
V
V
I
OUT
IN
OUT
FCB
= 15V
= 20mA
= 5V
= 5V
–
200mV/DIV
(Pins 4, 12): Receives the remotely-
(Pins 3, 13): The (–) Input to the
2A/DIV
V
I
OUT
OUT
2 s/DIV
Load Step (Figure 1)
V
V
LOAD STEP = 0A TO 3A
Burst Mode OPERATION
IN
OUT
= 15V
= 5V
1876 G33
20 s/DIV
CC
1876fa
1876 G30
or