LTC1871-1 LINER [Linear Technology], LTC1871-1 Datasheet - Page 9

• Manufacturer Part Number: LTC1871-1
• Description: High Effi ciency, Synchronous, 4-Switch Buck-Boost Controller
• Manufacturer: LINER [Linear Technology]

TYPICAL PERFORMANCE CHARACTERISTICS
500mV/DIV
PIN FUNCTIONS
PGOOD (Pin 1/Pin 30): Open-Drain Logic Output. PGOOD
is pulled to ground when the output voltage is not within
±7.5% of the regulation point.
SS (Pin 2/Pin 31): Soft-start reduces the input power
sources’ surge currents by gradually increasing the
controller’s current limit. A minimum value of 6.8nF is
recommended on this pin.
SENSE
and Reverse Current Detect Comparators. The I
5A/DIV
V
OUT
I
L
+
Load Step
V
V
LOAD STEP: 0A TO 5A
CONTINUOUS MODE
(Pin 3/Pin 1): The (+) Input to the Current Sense
IN
OUT
= 18V
= 12V
500mV/DIV
10V/DIV
1A/DIV
V
OUT
V
IN
I
L
200μs/DIV
Line Transient
V
I
V
CONTINUOUS MODE
LOAD
OUT
IN
STEP: 7V TO 20V
= 12V
= 1A
(SSOP/QFN)
500μs/DIV
3780 G27
500mV/DIV
5A/DIV
V
OUT
I
L
3780 G30
Load Step
V
V
LOAD STEP: 0A TO 5A
CONTINUOUS MODE
IN
OUT
= 12V
TH
= 12V
pin
200μs/DIV
voltage and built-in offsets between SENSE
pins, in conjunction with R
threshold.
SENSE
and Reverse Current Detect Comparators.
I
Amplifi er Compensation Point. The current comparator
threshold increases with this control voltage. The voltage
ranges from 0V to 2.4V.
TH
(Pin 5/Pin 3): Current Control Threshold and Error
500mV/DIV
–
10V/DIV
1A/DIV
(Pin 4/Pin 2): The (–) Input to the Current Sense
V
OUT
V
T
IN
I
L
A
3780 G28
Line Transient
V
I
V
CONTINUOUS MODE
LOAD
= 25°C, unless otherwise noted.
OUT
IN
STEP: 20V TO 7V
= 12V
= 1A
500mV/DIV
5A/DIV
V
OUT
500μs/DIV
I
L
Load Step
V
V
LOAD STEP: 0A TO 5A
CONTINUOUS MODE
IN
OUT
SENSE
= 6V
= 12V
, set the current trip
200μs/DIV
LTC3780
3780 G31
–
and SENSE
3780fe
9
3780 G29
+