ISL68137IRAZ datasheet(13/53 Pages) INTERSIL

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ISL68137

FN8757.0

September 27, 2016

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Functional Description

Overview

The ISL68137 is a digital dual output 7-phase PWM controller

that can be programmed for single output 7+0, dual output 6+1,

5+2, or 4+3 phase operation. Operation using less than 7 phases

between 2 outputs is also supported. Existing digital multiphase

solutions utilize analog comparator based schemes (nonlinear)

to bolster the inadequate transient response common to many

digital multiphase solutions. The ISL68137 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 ISL68137 can store up to 8 user

configurations in NVM and allows the user to select the desired

configuration via 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 ISL68137. These include AVSBus control, 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. Once a configuration has been set, the

user may employ PowerNavigator™ to monitor telemetry or use a

direct PMBus interface based on the supported command set.

PWM Modulation Scheme

The ISL68137 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 should the

load profile demand 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 ISL68137 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 via 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 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.

Automatic Phase Add and Drop

In order to produce the most optimal efficiency across a wide

range of output loading, the modulator supports automatic

dropping or adding of phases. Use of automatic phase dropping

is optional. If automatic phase dropping is enabled, the number

of active phases at any time is determined solely by load current.

During operation, phases of Output 1 will drop beginning with the

lowest phase number assigned. Phase dropping begins with the

highest assigned phase number. Figure 8 illustrates the typical

characteristic of efficiency vs load current vs phase count.

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

LOAD (A)

FIGURE 8. EFFICIENCY vs PHASE NUMBER

100

120

140

160

180

ISL68137IRAZ Datasheet(PDF) 13 Page - Intersil Corporation

ISL68137IRAZ Datasheet(HTML) 13 Page - Intersil Corporation

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