ISL68124IRAZ datasheet(11/46 Pages) RENESAS

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ISL68124

FN8796 Rev.2.00

Page 11 of 46

June 16, 2017

Functional Description

Overview

The ISL68124 is a digital dual output, 4-phase PWM controller that

can be programmed for single output 4+0, dual output 3+1, or

2+2 phase operation. Operation using less than four 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 ISL68124 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 ISL68124 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 ISL68124. 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, the PowerNavigator GUI

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 direct

PMBus interface based on the supported command set.

PWM Modulation Scheme

The ISL68124 uses Intersil's 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 ISL68124 supports up to two regulated outputs through four

configurable phases. Either output is capable of controlling up to

four phases in any arbitrary mix. Phase assignments are

accomplished through the PowerNavigator GUI.

While the device supports arbitrary phase assignment, it is good

practice to assign phases to Output 1 in descending sequential

numerical order starting from Phase 3. For example, a 3-phase

rail could consist of Phases 3, 2, and 1. For Output 0, phases

should be assigned starting from Phase 0 in ascending

sequential numerical order.

Typical Performance Curves

FIGURE 5. NOMINAL SUPPLY CURRENT vs TEMPERATURE

FIGURE 6. SHUTDOWN SUPPLY CURRENT vs TEMPERATURE

0.03

0.04

0.05

0.06

0.07

0.08

-40

-20

2040

6080

100

AMBIENT TEMPERATURE (oC)

0.01

0.02

0.03

0.04

0.05

-40

-20

406080

100

AMBIENT TEMPERATURE (oC)

TABLE 2. RESISTOR VALUES TO ADDRESS MAPPING

R SA

(Ω)

PMBus

ADDRESS

R SA

(Ω)

PMBus

ADDRESS

60h

1500

52h

180

63h

1800

53h

330

66h

2200

56h

470

67h

2700

57h

680

42h

3300

5Ah

820

43h

3900

5Bh

1000

46h

4700

5Eh

1200

47h

5600

5Fh

ISL68124IRAZ Datasheet(PDF) 11 Page - Renesas Technology Corp

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