ISL78229 Datasheet, PDF (40/71 Pages) Intersil Corporation – 2-Phase Boost Controller with Drivers

ISL78229
VIN
R_S
ISL78229
VIN
PVCC
PVCC
FIGURE 73. SUPPLEMENTING LDO CURRENT
PMBus™ User Guide
The ISL78229 is implemented with a PMBus™ digital interface
for the user to monitor and change a few operating parameters
allowing smart control of the regulator.
The Power Management Bus (PMBus™) is an open-standard
digital power management protocol. It uses SMBus as its
physical communication layer and includes support for the
SMBus Alert (SALERT). In much the same way as SMBus defines
the general means to manage portable power, PMBus™ defines
the means to manage power subsystems.
PMBus™ and SMBus are I²C derived bus standards that are
generally electrically compatible with I²C. They are more robust
(Timeouts Force Bus Reset) and offer more features than I²C,
like SMBALERT(SALERT) line for interrupts, Packet Error
Checking (PEC) and Host Notify Protocol.
The ISL78229 is compliant with the PMBus™ Power System
Management Protocol Specification Part I and II version 1.2.
These specification documents may be obtained from the
website http://PMBus™.org/Home. These are required reading
for complete understanding of the PMBus™ implementation.
• Specification Part I – General Requirements Transport and
Electrical Interface - Includes the general requirements,
defines the transport and electrical interface and timing
requirements of hardwired signals.
• Specification Part II – Command Language - Describes the
operation of commands, data formats, fault management and
defines the command language used with the PMBus™.
Monitor Operating Parameters via PMBus™
A system controller can monitor several ISL78229 operating
parameters through the PMBus™ interface including:
• Input voltage (monitors the VIN Pin)
• Output voltage (monitors the FB Pin)
• Input current (monitors the IMON Pin)
• External temperature (monitors the NTC Pin)
Monitor Faults and Configure Fault
Responses
When any of the 10 fault conditions in Table 4 on page 41 occur,
the corresponding bit of the FAULT_STATUS register will be set to 1
and the SALERT pin will be pulled low, regardless whether that
type of fault is masked by the FAULT_MASK register. The
PMBus™ host controller will get interrupted by monitoring the
SALERT pin and respond as follows:
• ISL78229 device pulls SALERT low.
• PMBus™ Host detects that SALERT is low, then performs
transmission with Alert Response Address to find which device
is pulling SALERT low.
• PMBus™ Host talks to the device that is pulling SALERT low.
The actions that the host performs next are up to the system
designer.
Each individual bit of the FAULT_STATUS register can only be
cleared to 0 by writing to that register via PMBus™, or by
CLEAR_FAULTS command, or POR recycle. When all the bits of
FAULT_STATUS register are reset to 0, the SALERT pin is release
to be pulled HIGH. Table 4 on page 41 lists the 10 types of faults
that can be accessed through PMBus™ to:
• Monitor or reset/clear each individual bit of the FAULT_STATUS
Register (D0h) for its corresponding fault's status.
• Configure the FAULT_MASK Register (D1h) to ignore or not to
ignore each individual fault's protection.
• Configure the SET_FAULT_RESPONSE Register (D2h) to set
each individual fault response to Hiccup or Latch-off.
Refer to “PMBus™ Command Detail” starting on page 46 for
details on each specific PMBus™ command.
Set Operation/Fault Thresholds via PMBus™
A system controller can change the ISL78229 operating
parameters through the PMBus™ interface. Below are some
commands but not limited to:
• Enable or disable the PWM operation and regulation
• Set output voltage
• Set output voltage changing slew rate
• Set output overvoltage thresholds
• Set output undervoltage thresholds
• Set input constant current control thresholds
Accessible Timing for PMBus™ Registers
Status
All the PMBus™ command registers are set to default values
during the part initialization period during t₂ - t₃ in Figure 67 on
page 30. All the PMBus™ registers (commands) are ready to be
accessed after this part initialization period.
After part start-up, as long as EN and PVCC/VCC is kept HIGH, all
the PMBus™ registers values are accessible via the PMBus™.
When the part is in Latch-off status or Hiccup mode triggered by
any fault in Table 4 on page 41, the internal LDO is still enabled
and keeps PVCC/VCC HIGH. All the PMBus™ register values are
accessible via PMBus™, the FAULT_STATUS register values are
accessible for the host to diagnose the type of fault.
Either EN low or PVCC/VCC falling below POR will disable the
ISL78229 and all the registers are reset and not accessible via
PMBus™.
Submit Document Feedback ₄₀
FN8656.3
February 12, 2016