ISL68137_16 Datasheet, PDF (17/53 Pages) Intersil Corporation – Digital Dual Output, 7-Phase Configurable PWM

ISL68137
V_IN
40.2k
IC
VINSEN
10nF
10k
ADC
FIGURE 17. INPUT VOLTAGE SENSE CONFIGURATION
Voltage Regulation
Output voltage is sensed through the remote sense differential
amplifier and digitized. From this point, the regulation loop is
entirely digital. Traditional PID controls are utilized in conjunction
with several enhanced methods to compensate the voltage
regulation loop and tune the transient response.
Current Feedback
Current feedback in a voltage regulator is often utilized to ease
the stability design of the voltage feedback path. Additionally,
many microprocessors require the voltage regulator to have a
controlled output resistance (known as load-line or droop
regulation) and this is accomplished utilizing current feedback.
For applications requiring droop regulation, the designer simply
specifies the output resistance desired using the
PowerNavigator™ GUI.
Current feedback stability benefits are available for rails that do
not specify droop regulation such as system agent. For these
applications, the designer may enable AC current feedback in the
GUI. With this configuration, the DC output voltage will be steady
regardless of load current.
Power-On Reset (POR)
Initialization of the ISL68137 begins after V_CC crosses its rising
POR threshold. When POR conditions are met, the internal 1.2V
LDO is enabled and basic digital subsystem integrity checks
begin. During this process, the controller will load the selected
user configuration from NVM as indicated by the CONFIG pin
resistor value, read VIN UVLO thresholds from memory and start
the telemetry subsystem. With telemetry enabled, V_IN may be
monitored to determine when it exceeds its user programmable
rising UVLO threshold. Once V_CC and V_IN satisfy their respective
voltage conditions, the controller is in its shutdown state. It will
transition to its active state and begin soft-start when the state of
EN0/EN1 command a start-up. While in shutdown mode, the
PWM outputs are held in a high-impedance state to assure the
drivers remain off.
Soft-Start Delay and Ramp Times
It may be necessary to set a delay from when an enable signal is
received until the output voltage starts to ramp to its target
value. In addition, the designer may wish to precisely set the time
required for an output to ramp to its target value after the delay
period has expired. These features may be used as part of an
overall inrush current management strategy or to precisely
control how fast a load IC is turned on. The ISL68137 gives the
system designer several options for precisely and independently
controlling both the delay and ramp time periods. The soft-start
delay period begins when the EN pin is asserted and ends when
the delay time expires.
The soft-start delay and ramp-up/down times can be configured
via PowerNavigator™ GUI. The device needs approximately
200µs after enable to initialize before starting to ramp up.
When the soft-start ramp period is set to 0ms, the output ramps
up as quickly as the output load capacitance and loop settings
allow. It is recommended to set the ramps to a non-zero value to
prevent inadvertent fault conditions due to excessive inrush
current.
Stored Configuration Selection
As many as eight configurations may be stored and used at any
time using the on-board nonvolatile memory. Configurations are
assigned an identifier number between 0 and 7 at power-up. The
device will load the configuration indicated by the 1% resistor
value detected on the CONFIG pin. Resistor values are used to
indicate use of one of the eight possible configurations. Table 3
provides the resistor value corresponding to each configuration
identifier.
TABLE 3. RESISTOR VALUES TO CONFIGURATION MAPPING
R CONFIG
(Ω)
CONFIG
ID
6800
0
1800
1
2200
2
2700
3
3300
4
3900
5
4700
6
5600
7
Only the most recent configuration with a given number can be
loaded. The device supports a total of 8 stored operations. As an
example, a configuration with the identifier 0 could be saved 8
times or configurations with all 8 identifiers could be stored one
time each for a total of 8 save operations.
PowerNavigator™ provides a simple interface to save and load
configurations.
Fault Monitoring and Protection
The ISL68137 actively monitors temperature, input voltage, output
voltage and output current to detect and report fault conditions.
Fault monitors trigger configurable protective measures to prevent
damage to a load. The power-good indicators, PG0/PG1, are
provided for linking to external system monitors.
A high level of flexibility is provided in the ISL68137 fault logic.
Faults may be enabled or disabled individually. Each fault type can
also be configured to either latch off or retry indefinitely.
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FN8757.0
September 27, 2016