PI352X-00 Datasheet, PDF (22/34 Pages) Vicor Corporation – 30VIN to 60VIN Cool-Power ZVS Buck Regulator

Functional Description
The PI352x-00 is a family of highly integrated ZVS-Buck
regulators. The PI352x-00 has an output voltage that can be set
within a prescribed range shown in Table 1. Performance and
maximum output current are characterized with a specific external
power inductor (see Table 3).
L1
V_IN
VIN
VS1
C_IN
ZVS-Buck VOUT
PGND
VSP
C_OUT
V_OUT
VDR
VSN
SYNCO
VDIFF
REA1
SYNCI
TRK
PWRGD
EAIN
EN
EAO
TESTx
COMP
REA2
SGND
C_COMP
Figure 54 — ZVS-Buck with required components
For basic operation, Figure 54 shows the connections
and components required. No additional design or
settings are required.
ENABLE (EN)
EN is the enable pin of the converter. The EN Pin is referenced
to SGND and permits the user to turn the regulator on or off.
The EN default polarity is a positive logic assertion. If the EN pin
is left floating or asserted high, the converter output is enabled.
Pulling EN pin below V_{EN_LO} with respect to SGND will disable the
regulator output.
Remote Sensing
If remote sensing is required, the PI352x-00 product family
is equipped with a general purpose op-amp. This amplifier
can allow full differential remote sense by configuring it as a
differential follower and connecting the V_DIFF pin to the EAIN pin.
PI352x-00
Soft-Start
The PI352x-00 includes an internal soft-start capacitor to
control the rate of rise of the output voltage. See the Electrical
Characteristics Section for the default value. Connecting an
external capacitor from the TRK pin to SGND will increase the
start-up ramp period. See, “Soft Start Adjustment and Track,” in
the Applications Description section for more details.
Output Voltage Selection
The PI352x-00 output voltage can be trimmed with REA1 and
REA2 as shown in Figure 54. Table 1 defines the allowable
operational voltage ranges for the PI352x-00 family. Refer to the
Output Voltage Set Point Application Description for details.
Device
PI3525-00-LGIZ
Output Voltage
Nom.
Range
5.0V
4.0V to 6.5V
PI3526-00-LGIZ
12V
6.5V to 14V
Table 1 — PI352x-00 family output voltage ranges
Output Current Limit Protection
The PI352x-00 has a current limit protection, which prevents
the output from sourcing current higher than the regulator’s
maximum rated current. If the output current exceeds the
Current Limit (I_{OUT_CL}) for 1024μs, a slow current limit fault is
initiated and the regulator is shutdown which eliminates output
current flow. After Fault Restart Delay (t_{FR_DLY}), a soft-start cycle
is initiated. This restart cycle will be repeated indefinitely until the
excessive load is removed.
The PI352x-00 also has short circuit protection which can
immediately stop switching to protect against catastrophic failure
of an external component such as a saturated inductor. If short
circuit protection is triggered the PI352x-00 will complete the
current cycle and stop switching. The module will attempt to soft-
start after Fault Restart Delay (t_{FR_DLY}).
Input Undervoltage Lockout
If V_IN falls below the input Undervoltage Lockout (UVLO)
threshold, but remains high enough to power the internal bias
supply, the PI352x-00 will complete the current cycle and stop
switching. The system will soft start once the input voltage is
reestablished and after the Fault Restart Delay.
Cool-Power^® ZVS Switching Regulators
Page 22 of 34
Rev 1.3
06/2017
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