LTC1709-8_15 Datasheet, PDF (7/28 Pages) Linear Technology – 2-Phase, 5-Bit VID, Current Mode, High Efficiency, Synchronous Step-Down Switching Regulators

LTC1709-8/LTC1709-9
TYPICAL PERFOR A CE CHARACTERISTICS
Current Sense Pin Input Current
vs Temperature
35
V_OUT = 5V
33
31
29
27
EXTV_CC Switch Resistance
vs Temperature
10
8
6
4
2
Oscillator Frequency
vs Temperature
350
V_FREQSET = 5V
300
250
V_FREQSET = OPEN
200
150
V_FREQSET = 0V
100
50
25
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
170989 G20
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
170989 G21
0
– 50 – 25
0 25 50 75
TEMPERATURE (°C)
100 125
170989 G22
Undervoltage Lockout
vs Temperature
3.50
3.45
3.40
3.35
3.30
3.25
3.20
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
170989 G23
Shutdown Latch Thresholds
vs Temperature
4.5
4.0
LATCH ARMING
3.5
3.0
LATCHOFF
THRESHOLD
2.5
2.0
1.5
1.0
0.5
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
170989 G24
PI FU CTIO S
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⁺, SENSE2⁺ (Pins 2,14): The (+) Input to Each
Differential Current Comparator. The I_TH pin voltage and
built-in offsets between SENSE^– and SENSE⁺ pins in
conjunction with R_SENSE set the current trip threshold.
SENSE1^–, SENSE2^– (Pins 3, 13): The (–) Input to the
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).
PLLFLTR (Pin 5): The phase-locked loop’s lowpass filter
is tied to this pin. Alternatively, this pin can be driven with
an AC or DC voltage source to vary the frequency of the
internal oscillator.
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