LTC1771IS8 Linear Technology, LTC1771IS8 Datasheet - Page 5

• Manufacturer Part Number: LTC1771IS8
• Description: IC CTRLR DC/DC STEPDOWN HE 8SOIC
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC1771IS8

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.23 ~ 18 V
• Current - Output: 5A
• Voltage - Input: 2.8 ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -
• Frequency - Switching: -

FUNCTIONAL BLOCK DIAGRA
PI FU CTIO S
RUN/SS (Pin 1): The voltage level on this pin controls
shutdown/run mode (ground = shutdown, open/high =
run). Connecting an external capacitor to this pin provides
soft-start.
I
current comparator threshold increases with this control
voltage. Nominal voltage range for this pin is 0V to 3V.
V
to Internal 1.23V Reference. An external resistive divider
across the output is returned to this pin.
GND (Pin 4): Ground Pin.
TH
FB
V
U
C
*
U
OUT
SS
(Pin 2): Error Amplifier Compensation Point. The
(Pin 3): Feedback of Output Voltage for Comparison
CURRENT LIMITING
OPTIONAL FOR FOLDBACK
R
C
C
*
C
RUN/SS
MODE
GND
I
TH
U
1
8
2
4
1.23V
(BURST ENABLE)
U
U
1V
–
+
1V
EA
V
IN
10% CURRENT
ON
1 A
+
–
B
MODE
2V
SOFT-START
ON TRIGGER
STRETCH
1-SHOT
W
READY
SLEEP
3.5 s
READY
PGATE (Pin 5): High Current Gate Driver for External
P-Channel MOSFET Switch. Voltage swing is from ground
to V
V
SENSE (Pin 7): Current Sense Input for Monitoring Switch
Current. Maximum switch current and Burst Mode
threshold is programmed with an external resistor be-
tween SENSE and V
MODE (Pin 8): Burst Mode Enable/Disable Pin. Connect-
ing this pin to V
operation, while connecting this pin to ground disables
Burst Mode operation. Do not leave floating.
IN
(Pin 6): Main Input Voltage Supply Pin.
IN
.
REFERENCE
1.23V
V
IN
10% CURRENT
IN
IN
(or above 2V) enables Burst Mode
ON
BLANKING
.
V
3
C
FB
+
–
22k
250k
R2
R1
SENSE
PGATE
V
6
5
7
IN
D1
LTC1771
+
L
R
SENSE
C
OUT
+
C
5
IN
1771 BD
V
V
IN
OUT