ADP1875 Analog Devices, ADP1875 Datasheet - Page 26

• Manufacturer Part Number: ADP1875
• Description: Synchronous Buck Controller with Constant On-Time, Valley Current Mode, and Power Saving Mode
• Manufacturer: Analog Devices

ADP1874/ADP1875
The slave output tracks the master output dv/dt until the slave
output regulation point is reached. Any influence by the master
voltage thereafter will no longer be in effect. Ensure that the voltage
forced on the slave TRACK pin is above 0.7 V at the end of TRACK
phase. Voltages imposed on the TRACK pin below 0.7 V, once
that tracking period has expired (steady state), may result in
regulation inaccuracies due to the internal offsets of the error
amplifier between TRACK and FB. Ratiometric tracking can be
achieved by assigning the slave output to rise more quickly than
the master voltage. The simplest way to perform ratiometric
tracking is to differentially connect the slave TRACK pin to the
FB pin of the master voltage IC. The slave output, however, must
be limited to a fraction of the master voltage. In this tracking
configuration, it is not recommended for the slave TRACK pin
to terminate at a voltage lower than 0.6 V due to inaccuracies
between the TRACK and FB inputs previously mentioned. It is
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not recommended to force any voltage on the slave TRACK pin
lower than 0.6 V. Figure 84 illustrates a circuit with a ratiometric
tracking configuration. Setting R
slave TRACK voltage will rise up more quickly (to the regulation
point) than the master voltage.
Figure 84. Ratiometric Tracking: Master Voltage—Slave Voltage Tracking
MASTER VOLTAGE
SLAVE VOLTAGE
Relationship
TIME (ms)
TRK1
> R
TRK2
ensures that the