LTC3709_15 Datasheet, PDF (7/24 Pages) Linear Technology – Fast 2-Phase, No RSENSE Synchronous DC/DC Controller with Tracking/Sequencing

TYPICAL PERFOR A CE CHARACTERISTICS
LTC3709
Maximum Current Sense
Threshold Voltage vs V_RNG
350
300
250
200
150
100
50
0
0.5 0.8 1.1 1.4 1.7 2.0
V_RNG (V)
3709 G19
Minimum Current Sense
Threshold Voltage vs V_RNG
0
–20
–40
–60
–80
–100
–120
–140
0.5 0.8 1.1 1.4 1.7 2.0
V_RNG (V)
3709 G20
PI FU CTIO S (QFN/SSOP)
RUN/SS (Pin 1/Pin 6): Run Control and Soft-Start Input.
A capacitor to ground at this pin sets the ramp rate of the
output voltage (approximately 0.5s/µF) and the time delay
for overcurrent latch-off (see Applications Information).
Forcing this pin below 1.4V shuts down the device.
I_TH (Pin 2/Pin 7): Error Amplifier Compensation Point. The
current comparator threshold increases with this control
voltage. The voltage ranges from 0V to 2.4V with 0.8V
corresponding to zero sense voltage (zero current).
V_FB (Pin 3/Pin 8): Error Amplifier Feedback Input. This pin
connects to the error amplifier input. It can be used to
attach additional compensation components if desired.
TRACK (Pin 4/Pin 9): Tie the TRACK pin to a resistive
divider connected to the output of another LTC3709 for
either coincident or ratiometric output tracking (see Appli-
cations Information). To disable this feature, tie the pin to
V_CC. Do Not Float this pin.
SGND (Pins 5, 6, 33/Pins 10, 11): Signal Ground. All
small-signal components such as C_SS and compensation
components should connect to this ground and eventually
connect to PGND at one point. The Exposed Pad of the QFN
package must be soldered to PCB ground.
V_OS– (Pin 7/Pin 12): The (–) Input to the Differential
Amplifer.
DIFFOUT (Pin 8/Pin 13): The Output of the Differential
Amplifier.
V_OS+ (Pin 9/Pin 14): The (+) Input to the Differential
Amplifier.
EXTLPF (Pin 10/Pin 15): Filter Connection for the PLL.
This PLL is used to synchronize the LTC3709 with an
external clock.
INTLPF (Pin 11/Pin 16): Filter Connection for the PLL.
This PLL is use to phase shift the second channel to the
first channel by 180°.
3709fb
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