ISL68147IRAZ datasheet(12/47 Pages) RENESAS

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ISL68147

FN8880 Rev.2.00

Page 12 of 47

Jul 14, 2017

Functional Description

Overview

The ISL68147 is a digital dual output, 7-phase PWM controller

that can be programmed for a single output 7+0, dual output

6+1, 5+2, or 4+3 phase operation. Operation using less than

seven phases between two outputs is also supported. Existing

digital multiphase solutions use analog comparator-based

schemes (nonlinear) to bolster the inadequate transient

response common to many digital multiphase solutions. The

ISL68147 uses a linear voltage regulation scheme to address

transient loads. As a result, it is much easier for users to

configure and validate their designs when compared with

nonlinear schemes. By combining a proprietary low noise and

zero latency digital current sense scheme with cutting edge

digital design techniques, Intersil is able to meet transient

demands without resorting to nonlinear schemes. In addition,

the ISL68147 can store up to eight user configurations in NVM

and allows the user to select the desired configuration through

pin-strap (CONFIG). The result is a system that is easy to

configure and deploy.

A number of performance enhancing features are supported in

the ISL68147. These include diode braking, automatic phase

dropping, DCR/resistor/smart power stage current sense

support, load line regulation, and multiple temperature sensing

options.

To facilitate configuration development, PowerNavigator provides

a step-by-step arrangement for setup and parametric

adjustment. After a configuration has been set, the user can

employ PowerNavigator to monitor telemetry or use the direct

PMBus interface based on the supported command set.

PWM Modulation Scheme

The ISL68147 uses the Intersil proprietary linear synthetic current

modulation scheme to improve transient performance. This is a

unique, constant frequency, dual-edge PWM modulation scheme

with both PWM leading and trailing edges being independently

moved to give the best response to transient loads. Current

balance is an inherent part of the regulation scheme. The

modulation scheme is capable of overlapping pulses if the load

profile demands such operation. In addition, the modulator is

capable of adding or removing pulses from a given cycle in

response to regulation demands while still managing maximum

average frequency to safe levels. For DC load conditions, the

operating frequency is constant.

PMBus Address Selection

When communicating with multiple PMBus devices on a single

bus, each device must have its own unique address so the host

can distinguish between the devices. The device address can be

set using a 1% resistor on the SA pin according to the pin-strap

options listed in Table 2.

Phase Configuration

The ISL68147 supports up to two regulated outputs through

seven configurable phases. Either output is capable of controlling

up to seven phases in any arbitrary mix. Phase assignments are

accomplished using PowerNavigator.

Although the device supports arbitrary phase assignment, it is

good practice to assign phases to Output 1 in descending

sequential numerical order starting from Phase 6. For example, a

4-phase rail could consist of Phases 6, 5, 4, and 3. For Output 0,

phases would be assigned starting from Phase 0 in ascending

sequential numerical order.

Typical Performance Curves

FIGURE 6. NOMINAL SUPPLY CURRENT vs TEMPERATURE

FIGURE 7. SHUTDOWN SUPPLY CURRENT vs TEMPERATURE

0.050

0.055

0.060

0.065

0.070

0.075

0.080

0.085

0.090

0.095

0.100

-40

-20

20406080

100

AMBIENT TEMPERATURE (oC)

0.01

0.02

0.03

0.04

0.05

-40

-20

2040

6080

100

AMBIENT TEMPERATURE (oC)

TABLE 2. RESISTOR VALUES TO ADDRESS MAPPING

R SA

(Ω)

PMBus

ADDRESS

R SA

(Ω)

PMBus

ADDRESS

60h

1500

50h

180

61h

1800

51h

330

64h

2200

54h

470

65h

2700

55h

680

40h

3300

58h

820

41h

3900

59h

1000

44h

4700

5Ch

1200

45h

5600

5Dh

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