SI3201-X-FS SILABS [Silicon Laboratories], SI3201-X-FS Datasheet - Page 23

• Manufacturer Part Number: SI3201-X-FS
• Manufacturer: SILABS [Silicon Laboratories]

Parameter
Loop Closure
Interrupt Pending
Loop Closure
Interrupt Enable
Loop Closure Threshold
Loop Closure
Threshold—Lower
Loop Closure Filter
Coefficient
Loop Closure Detect
Status (monitor only)
Loop Closure Detect
Debounce Interval
Hysteresis Enable
Voltage-Based Loop
Closure
2.2.8. Voltage-Based Loop Closure Detection
An optional voltage-based loop closure detection mode
is enabled by setting LCVE = 1 (direct Register 108,
bit 2). In this mode, the loop voltage is compared to the
loop
represents a minimum voltage threshold instead of a
maximum current threshold. If hysteresis is also
enabled, LCRT represents the upper voltage boundary,
and LCRTL represents the lower voltage boundary for
hysteresis.
detection is an option, the default current-based loop
closure detection is recommended.
2.2.9. Linefeed Calibration
An internal calibration algorithm corrects for internal and
external component errors. The calibration is initiated by
setting the CAL bit in direct Register 96. Upon
completion of the calibration cycle, this bit is
automatically reset.
It is recommended that a calibration be executed
following system power-up. Upon release of the chip
reset, the Si3233 will be in the open state. After
powering up the dc-dc converter and allowing it to settle
for time (t
Additional calibrations may be performed, but only one
calibration should be necessary as long as the system
remains powered up.
During calibration, V
controlled by the calibration engine to provide the
correct external voltage conditions for the algorithm.
Calibration should be performed in the on-hook state.
closure
Table 23. Register Set for Loop
settle
Although
) the calibration can be initiated.
threshold
Closure Detection
BAT
, V
voltage-based
NCLR[12:0] Indirect Reg. 22
LCRTL[5:0] Indirect Reg. 66
LCRT[5:0]
LCDI[6:0]
HYSTEN
TIP
Register
register
LCVE
LCIP
LCIE
LCR
, and V
RING
(LCRT),
Indirect Reg. 15
Direct Reg. 108
Direct Reg. 108
Direct Reg. 19
Direct Reg. 22
Direct Reg. 68
Direct Reg. 69
loop
voltages are
Location
Preliminary Rev. 0.5
closure
which
RING or TIP must not be connected to ground during
the calibration.
2.3. Battery Voltage Generation and
Switching
The Si3233 integrates a dc-dc converter controller that
dynamically regulates a single output voltage. This
eliminates the need to supply large external battery
voltages. Instead, it converts a single positive input
voltage into the real-time battery voltage needed for any
given
parameters.
2.3.1. DC-DC Converter General Description
The dc-dc converter dynamically generates the large
negative voltages required to operate the linefeed
interface. The Si3233 acts as the controller for a buck-
boost dc-dc converter that converts a positive dc
voltage into the desired negative battery voltage. In
addition to eliminating external power supplies, this
allows the Si3233 to dynamically control the battery
voltage to the minimum required for any given mode of
operation.
Extensive design guidance can be obtained from
Application Note 45 (AN45) and from an interactive dc-
dc converter design spreadsheet. Both of these
documents are available on the Silicon Laboratories
website (www.silabs.com).
2.3.2. BJT/Inductor Circuit Using Si3233
The BJT/Inductor circuit, as defined in Figure 4, offers a
flexible, low-cost solution. Depending on selected L1
inductance value and the switching frequency, the input
voltage (V
dc-dc converter’s operation, peak and average input
currents can become large with small input voltages.
Consider this when selecting the appropriate input
voltage and power rating for the V
In this circuit, a PNP power BJT (Q7) switches the
current flow through low ESR inductor L1. The Si3233
uses the DCDRV and DCFF pins to switch Q7 on and
off. DCDRV controls Q7 through NPN BJT Q8. DCFF is
ac coupled to Q7 through capacitor C10 to assist R16 in
turning off Q7. Therefore, DCFF must have opposite
polarity to DCDRV, and the Si3233 (not Si3233M) must
be used.
2.3.3. MOSFET/Transformer Circuit Option Using
The MOSFET/transformer circuit option, as defined in
Figure 5, offers higher power efficiencies across a larger
input voltage range. Depending on the transformer’s
primary inductor value and the switching frequency, the
input voltage (V
Therefore, it is possible to power the entire ProSLIC
Si3233M
state
DC
) can range from 5 V to 30 V. By nature of a
according
DC
) can range from 3.3 V to 35 V.
to
programmed
DC
power supply.
Si3233
linefeed
23