LTC3709 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
RUN/SS (Pin 1): Run Control and Soft-Start Input. A ca-
pacitor to ground at this pin sets the ramp rate of the out-
put voltage (approximately 0.5s/µF) and the time delay for
overcurrent latch-off (see Applications Information). Forc-
ing this pin below 1.4V shuts down the device.
I_TH (Pin 2): 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): 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): Tie the TRACK pin to a resistive divider
connected to the output of another LTC3709 for either
coincident or ratiometric output tracking (see Applica-
tions Information). To disable this feature, tie the pin to
V_CC. Do Not Float this pin.
SGND (Pins 5, 6, 33): 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): The (–) Input to the Differential Amplifer.
DIFFOUT (Pin 8): The Output of the Differential Amplifier.
V_OS+ (Pin 9): The (+) Input to the Differential Amplifier.
EXTLPF (Pin 10): Filter Connection for the PLL. This PLL
is used to synchronize the LTC3709 with an external clock.
INTLPF (Pin 11): Filter Connection for the PLL. This PLL
is use to phase shift the second channel to the first channel
by 180°.
NC (Pin 12): No Connect.
3709f
7