Datasheet

V33
To12 -bit ADC
Resistorto
setPMBus
Address
UCD9248
ADDR-0,
ADDR-1pins
10 A
I
m
BIAS
UCD9248
SLVSA33A –JANUARY 2010–REVISED AUGUST 2012 www.ti.com
FUNCTIONAL OVERVIEW
The UCD9248 contains four fusion power peripherals (FPP). Each FPP can be configured to regulated up to four
DC/DC converter outputs. There are eight PWM outputs that can be assigned to drive the converter outputs.
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 configured through a 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 UCD9248 supports revision 1.1 of the PMBus
standard. Wherever possible, standard PMBus commands are used to support the function of the device. For
unique features of the UCD9248, MFR_SPECIFIC commands are defined to configure or activate those features.
These commands are defined in the UCD92xx PMBUS Command Reference.
The UCD9248 is PMBus compliant, in accordance with the Compliance section of the PMBus specification. The
firmware is also compliant with the SMBus 1.1 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
Two pins are allocated to decode the PMBus address. At power-up, the device applies a bias current to each
address detect pin, and the voltage on that pin is captured by the internal 12-bit ADC. The PMBus address is
calculated as follows:
PMBus Address = 12 × PMBus Address 1 + PMBus Address 0
Where PMBus Address 1 and 0 are selected from Table 1.
Figure 5. PMBus Address Detection Method
Table 1. PMBus Address Bins
R
PMBus
PMBus RESISTANCE
PMBus ADDRESS
(kΩ)
open –
11 205
10 178
9 154
8 133
7 115
6 100
12 Submit Documentation Feedback Copyright © 2010–2012, Texas Instruments Incorporated