Intersil HIP6302EVAL1 Application Note

TM

FIGURE 2. HIP6601A BLOCK DIAGRAM

PVCC 7 2 BOOT

VCC 6

CONTROL

LOGIC

SHOOT

THROUGH

PROTECTION

+5V

PWM 3

10k

UGATE

PHASE

LGATE

1

8

5

4

GND

10k

HIP6302EVAL1 - Multiphase Power Conversion

for AMD Athlon Processors up to 35A

Application Note February 2002

Introduction

Each generation of computer microprocessor brings
performance advances in computing power. Performance
improvements are made possible by advances in fabrication
technology that enable greater device density. Newer
processors are operating at lower voltages and higher clock
speeds both of which contribute to greater demands on the
microprocessor core voltage supply in terms of higher peak
currents and higher current-slew rates.

Intersil’s family of multi-phase DC-DC converter solutions
provide the ideal solution to supply the core-voltage needs of
present and future high-performance microprocessors.

Intersil HIP6302 and HIP6601

The HIP6302 controller IC works with two HIP6601A or
HIP6603A single-channel driver ICs or a single HIP6602A
dual-channel driver IC [3] to form a highly integrated solution
for high-current, high slew-rate applications. The HIP6302
regulates output voltage, balances load currents and
provides protective functions for two synchronous-rectified
buck-converter channels.

AN9888.1

Author: Matt Harris

provides feedback for droop compensation and over-current
protection. A five-bit DAC provides a digital interface to
program the 1% accurate reference and a window
comparator toggles PGOOD if the output voltage is out of
range and acts to protect the load in case of over voltage.
For more detailed descriptions of the HIP6302 functionality,
refer to the HIP6302 Data Sheet [1].

The HIP6601A is a driver IC capable of delivering up to 2A of
gate-charging current for rapidly switching both MOSFETs in
a synchronous-rectified bridge. The HIP6601A accepts a
single logic input to control both upper and lower MOSFETs.
Adaptive shoot-through protection is provided on both
switching edges to provide optimal dead time, and bootstrap
circuitry permits greater enhancement of the upper
MOSFET. For a more detailed description of the HIP6601A,
refer to the HIP6601A Data Sheet [2].

PGOOD VCC

15

VSEN

10

x 0.9

x 1.15

COMP

6

1VID4
2VID3
3VID2

DAC

4VID1
5VID0

7FB

The integrated high-bandwidth error amplifier provides
voltage regulation, while current-sense circuitry maintains

UV

+

­OV

LATCH

S

OVP

+

-

SOFT START

AND FAULT

LOGIC

+

-

∑

FIGURE 1. HIP6302 BLOCK DIAGRAM

+

-

E/A

CURRENT

DETECTION

+

+

9

phase-current balance between the two power channels and

16

POWER-ON

RESET (POR)

THREE STATE

CLOCK AND

SAWTOOTH

GENERATOR

∑

+

∑

-

GND

PWM

+

-

PWM

+

-

8

FS/DIS

13

PWM1

12

PWM2

1411ISEN1

ISEN2

The HIP6302EVAL1 Board and Reference
Design

With the VID jumpers set to 1.7V (00110), the evaluation
board meets the output voltage and current specifications
indicated in Table 1.

TABLE 1. HIP6302EVAL1 OUTPUT PARAMETERS

MIN MAX

Static Regulation 1.65V 1.75V

Transient Regulation 1.60V 1.85V

Over-Voltage Protection 1.90V 2.00V

Continuous Load Current - 35A

Over-Current Trip Level 41A 57A

Load-Current Transient - 35A/µs

1

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 321-724-7143

|

Intersil (and design) is a trademark of Intersil Americas Inc.

Copyright © Intersil Americas Inc. 2002. All Rights Reserved

PGOOD, 5V/DIV

1ms/DIV

0A

0V

0V

0V

ICC5, 10A/DIV

VCORE, 1V/DIV

FS/EN, 5V/DIV

FIGURE 3. HIP6302EVAL1 START-UP WAVEFORMS

Application Note AN9888

The HIP6302EVAL1 evaluation board incorporates a
reference design intended to meet the core-voltage
requirements for AMD Athlon



microprocessors up to 35A.
Additional circuitry is provided to facilitate circuit evaluation
including input and output power connectors, VID jumpers,
numerous probe points, an LED power-good indicator, and a
load-transient generator.

Powering the HIP6302EVAL1

For convenience, the HIP6302EVAL1 provides two methods
of making input power connections. The 20-pin header, J1,
interfaces with a standard ATX power supply and may be the
most convenient method of powering the board.

J2, J3, and J4 are standard banana-jack connectors that can
be used to supply power using bench-top power supplies.
These inputs provide greater versatility in testing and design
validation by allowing the 12V and 5V power-input voltage
levels to be varied independently. In this way power-on level
and power-sequencing issues can be easily examined.

To start the evaluation board, insert the 20-pin connector
from an ATX supply into J1. If using bench-top supplies,
connect a 12V supply to J2 and a 5V supply to J3. Connect
the grounds from both supplies to J4.

Start Up

The waveforms in Figure 3 demonstrate the normal start-up
sequence with the HIP6302EVAL1 connected to a 55m
load. After FS/EN is released, VCORE exhibits a linear ramp
until reaching its 1.7V set point. The gradual increase of
VCORE over approximately 5ms limits the current required
from the input supply, ICC5, to a level that does not strain the
supply. The HIP6302 asserts PGOOD once VCORE is within
regulation limits.

Ω

Important

There are two things to consider when using bench-top
supplies. If the 5V supply is applied prior to the 12V supply,
the HIP6302 will begin operating before the HIP6601As. This
allows the HIP6302 to complete its soft-start cycle before the
drivers are capable of switching power to the output. When
the 12V power input is then applied, there is a large transient
as the controller tries to instantly bring the output to its full­voltage level. This can result in an overcurrent protection
cycle and an abnormal start-up waveform. It can be avoided
by applying 5V supply after or at the same time as the 12V
supply or by using an ATX power supply.

The second problem can occur when operating the transient
load generator. Not all bench-top and ATX power supplies
are capable of responding to load transients, and they may
allow a momentary voltage dip on VCC5. This can activate
the power-on-reset function in the HIP6302 and cause the
output power to cycle. It can be remedied by connecting a
5600

µ F or larger capacitor between VCC5 and ground. The

capacitor, if necessary, simulates the distributed capacitance
that exists on the computer motherboard.

Transient Response

The HIP6302EVAL1 is equipped with a load-transient
generator that applies a 0–36A transient load current with
rise and fall rates of approximately 35A/
the transient is between 100

µ

s and 200 µ
rate is kept low in order to limit power dissipation in the load
MOSFETs and resistors. Removal of the HI/LO jumper (JP2)
causes the current to decrease from about 36A to about
31A. The load-transient generator operates when the
HIP6302EVAL1 is properly connected to a 12V power
source and SW1 is in the ON position. Operation ceases
when SW1 is moved into the OFF position or 12V is
removed from the board.

The HIP6302EVAL1 achieves the specified transient
performance while maintaining a favorable balance between
low cost, high efficiency and small profile. When the duty
cycle changes rapidly in response to a transient load current,
the inductor current immediately begins to change in order to
meet the demand. During the time the inductor current is
increasing, the output-filter capacitors are supplying the
load. It follows that the amount of required capacitance
decreases as the capability of the inductors to rapidly
assume the load current increases.

µ

s. The duration of

s, and the repetition

2

Athlon™ is a trademark of Advanced Micro Devices, Inc.

3

5µs/DIV

0V

0A

1.7V

0V

PWM2, 10V/DIV

CORE VOLTAGE,

FIGURE 6. TRANSIENT-RESPONSE TRAILING EDGE

PWM1, 10V/DIV

INDUCTOR CURRENTS,

10A/DIV

50mV/DIV

FIGURE 7. OVERCURRENT BEHAVIOR

50µs/DIV

0A

0V

0V

CORE VOLTAGE,

OUTPUT CURRENT,

PWM1, 5V/DIV

20A/DIV

500mV/DIV

Application Note AN9888

Figure 4 shows the core voltage, inductor current, and PWM
signals changing in response to the transient load current.
The upper waveform shows the core voltage deviating from
its no-load setting of 1.72V to a minimum of about 1.62V
upon the application of current. The voltage then settles to its

1.67V full-load setting. On load removal, the core voltage
peaks at a level of 1.78V before settling again to its 1.72V
no-load setting. Although the specified operating range
allows deviations as low as 1.60V and as high as 1.85V, a
minimum of 20mV is reserved to allow for the reference
tolerance and the tolerances of other components that
contribute to the overall system accuracy.

CORE VOLTAGE, 50mV/DIV

1.7V

INDUCTOR CURRENTS, 10A/DIV

0A

0V

0V

FIGURE 4. HIP6302EVAL1 TRANSIENT RESPONSE

PWM1, 10V/DIV

PWM2, 10V/DIV

20µs/DIV

Figure 5 is a close-up showing the core-voltage, inductor­current and PWM signals responding at the leading edge of
the transient load

current. The PWM signals increase to their
maximum duty cycle of 75% on the first pulse following the
start of the transient. The inductor currents begin to increase
immediately and are carrying all of the load within 10

µ s. The

very fast transient response is due to the precision 18MHz
error amplifier and optimal compensation of the control loop.

The close up in Figure 6 shows the core-voltage, inductor­current and PWM signals changing in response to the
trailing edge of the transient load current. Again, the duty
cycles immediately decrease to zero, and the inductors
begin shedding load current at the maximum rate. Note that
the inductor currents briefly go negative as the transient
settles. The capacitors are slightly over charged at the end of
the transient, and the discharge path is in the reverse
direction through the inductors.

Overcurrent Protection

µ

When the current out of either ISEN pin exceeds 82
HIP6302 detects an overcurrent condition and responds by
placing the PWM outputs into a high-impedance state. This
signals the HIP6601 to turn off both upper and lower
MOSFETs in order to remedy the overcurrent condition.This
behavior is seen in Figure 7 where PWM1 goes immediately to

2.5VDC when the output current reaches approximately 50A.
The output voltage then quickly falls to zero.

A, the

1.7V

CORE VOLTAGE, 50mV/DIV

INDUCTOR CURRENTS,

10A/DIV

0A

0V

0V

FIGURE 5. TRANSIENT-RESPONSE LEADING EDGE

PWM1, 10V/DIV

5µs/DIV

PWM2, 10V/DIV

4

Application Note AN9888

After the initial over-current trip, the HIP6302 waits for a
period of time equal to 2048/f

SW

(f

is the switching

SW

frequency) before initiating a soft-start cycle. If the over-load
condition remains, another over-current trip will occur before
the end of the soft-start sequence. This repetitive over­current cycling is illustrated in Figure 8, and will continue
indefinitely unless the fault is cleared or power to the
converter is removed. Because of the wait period, the worst
case power delivered during overcurrent cycling is equal to
45% of the power delivered during normal operation at full
load. Therefore, indefinite over-current cycling does not
create a thermal problem for the circuit.

OUTPUT CURRENT, 20A/DIV

0A

CORE VOLTAGE,
500mV/DIV

0V

FIGURE 8. OVERCURRENT BEHAVIOR

5ms/DIV

Efficiency

Figure 9 shows the efficiency versus current plot for the
HIP6302EVAL1 for 5A through 35A. The measurements
were made at room temperature with natural convection
cooling only..

90

Summary

The HIP6302EVAL1 is intended to provide a convenient
platform to evaluate the performance of the HIP6302 ­HIP6601A chip set in the specific implementation indicated
in Table 1. The design demonstrates a favorable trade off
between low cost, high efficiency, and small footprint. The
following pages include schematic, bill of materials, and
layout drawings to facilitate implementation of this solution.
The evaluation board is simple and convenient to operate,
and test points are available to evaluate the most commonly
tested parameters. Example waveforms are given for
reference.

The HIP6302 and HIP6601A provide a versatile 2-phase
power solution for low-voltage applications from 25A to
approximately 40A, and together they result in the most
effective solution available.

References

For Intersil documents available on the internet, see web site
http://www.intersil.com/
Intersil Technical Support 1 (888) INTERSIL

[1] HIP6302 Data Sheet, Intersil Corporation, Power

Management Products Division, 2000.
(http://www.intersil.com/).

[2]

HIP6601A, HIP6603A Data Sheet,

Power Management Products Division, 2000.

[3]

HIP6602A Data Sheet,

Intersil Corporation, Power

Management Products Division, 2000.

Intersil Corporation,

85

80

EFFICIENCY (%)

75

70

5101520253035

CURRENT (AMPERES)

FIGURE 9. EFFICIENCY vs CURRENT