ltc1709-85 Linear Technology Corporation, ltc1709-85 Datasheet - Page 7

• Manufacturer Part Number: ltc1709-85
• Description: 2-phase, 5-bit Vid, Current Mode, High Efficiency, Synchronous Step-down Switching Regulator
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
TYPICAL PERFOR A CE CHARACTERISTICS
RUN/SS (Pin 1): Combination of Soft-Start, Run Control
Input and Short-Circuit Detection Timer. A capacitor to
ground at this pin sets the ramp time to full current output.
Forcing this pin below 0.8V causes the IC to shut down all
internal circuitry. All functions are disabled in shutdown.
SENSE1
Differential Current Comparator. The I
built-in offsets between SENSE
conjunction with R
–11
–13
–12
–10
–8
–9
U
–50 –25
Current Sense Pin Input Current
vs Temperature
V
OUT
+
, SENSE2
= 1.6V
U
0
TEMPERATURE ( C)
25
3.20
3.50
3.45
3.40
3.35
3.30
3.25
SENSE
+
–50
U
(Pins 2,14): The (+) Input to Each
50
Undervoltage Lockout
vs Temperature
–25
set the current trip threshold.
75
W
100
0
170985 G20
TEMPERATURE ( C)
–
U
125
25
and SENSE
50
TH
pin voltage and
75
10
6
0
8
4
2
–50 –25
EXTV
vs Temperature
100
+
170985 G23
pins in
CC
125
Switch Resistance
0
TEMPERATURE ( C)
25
SENSE1
Differential Current Comparators.
EAIN (Pin 4): Input to the error amplifier that compares the
feedback voltage to the internal 0.8V reference voltage.
This pin is normally connected to a resistive divider from
the output of the differential amplifier (DIFFOUT).
50
75
4.5
4.0
3.5
3.0
2.5
2.0
1.0
1.5
0.5
–
, SENSE2
0
100
–50
170985 G21
V
Thresholds vs Temperature
RUN/SS
125
–25
Shutdown Latch
–
0
TEMPERATURE ( C)
(Pins 3, 13): The (–) Input to the
THRESHOLD
350
300
200
150
100
250
LATCHOFF
25
50
0
– 50
Oscillator Frequency
vs Temperature
LATCH ARMING
50
– 25
75
0
TEMPERATURE ( C)
100
LTC1709-85
170985 G24
V
25
V
PLLFLTR
PLLFLTR
125
50
= 2.4V
= 0V
75
100
170985 G22
170985f
7
125