Datasheet

V33
To 12 -bit ADC
Resistor to
set PMBus
Address
ADDR - 0,
ADDR - 1 pins
10 A
I
m
BIAS
UCD9244
SLVSAL6A –NOVEMBER 2010– REVISED FEBRUARY 2011 www.ti.com
FUNCTIONAL OVERVIEW
The UCD9244 contains four Fusion Power Peripherals (FPP). Each FPP consists of:
• A differential input error voltage amplifier.
• A 10-bit DAC used to set the output regulation reference voltage.
• A fast ADC with programmable input gain to digitally measure the error voltage.
• A dedicated 3-pole/3-zero digital filter to compensate the error voltage
• A digital PWM (DPWM) engine that generates the PWM pulse width based on the compensator output.
Each controller is configurable through the PMBus serial interface.
PMBus Interface
The PMBus is a serial interface specifically designed to support power management. It is based on the SMBus
interface that is built on the I
2
C physical specification. The UCD9244 supports revision 1.2 of the PMBus
standard. Wherever possible, standard PMBus commands are used to support the function of the device. For
unique features of the UCD9244, MFR_SPECIFIC commands are defined to configure or activate those features.
These commands are defined in the UCD92xx PMBUS Command Reference.
The UCD9244 is PMBus compliant, in accordance with the "Compliance" section of the PMBus specification. The
firmware is also compliant with the SMBus 2.0 specification, including support for the SMBus ALERT function.
The hardware can support 100 kHz, 400 kHz, or 1 MHz PMBus operation.
Resistor Programmed PMBus Address Decode
The PMBus Address is selected using resistors attached to the ADDR0 and ADDR1 pins. At power-up, the
device applies a bias current to each address detect pin. The measured voltage on each pin determines the
PMBus address as defined in Table 2. For example, a 133kΩ resistor on ADDR1 and a 75kΩ on ADDR0 will
select PMBus address = 100. Resistors are chosen from the standard EIA-E96 series, and should have accuracy
of 1% or better.
Figure 4. PMBus Address Detection Method
A short or open on either address pin causes the PMBus address to default to address 126. To avoid potential
conflicts between multiple devices, it is best to avoid using address 126.
Some addresses should be avoided; see Table 2 for details.
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