HIP6301V, HIP6302V

FN9034 Rev 3.00

Page 8 of 20

May 5, 2008

Operation

Figure 1 shows a simplified diagram of the voltage regulation

and current control loops. Both voltage and current feedback

are used to precisely regulate voltage and tightly control the

voltage loop comprises the error amplifier, comparators, gate

drivers and output MOSFETs. The error amplifier is

essentially connected as a voltage follower that has as an

input, the programmable reference DAC and an output that

is the CORE voltage.

Voltage Loop

to the inverting input of the error amplifier. This signal can

drive the error amplifier output either high or low, depending

upon the CORE voltage. Low CORE voltage makes the

amplifier output move towards a higher output voltage level.

Amplifier output voltage is applied to the positive inputs of

the comparators via the correction summing networks.

Out-of-phase sawtooth signals are applied to the two

Comparators inverting inputs. Increasing error amplifier

voltage results in increased comparator output duty cycle.

This increased duty cycle signal is passed through the PWM

CIRCUIT with no phase reversal and on to the HIP6601B,

again with no phase reversal for gate drive to the upper

the MOSFET transistors results in increased output voltage

to compensate for the low output voltage sensed.

Current Loop

The current control loop works in a similar fashion to the

voltage control loop, but with current control information

applied individually to each channel’s comparator. The

information used for this control is the voltage that is

scales the voltage across the MOSFETs to a current that is

applied to the current sensing circuit within the controller.

Output from these sensing circuits is applied to the current

averaging circuit. Each PWM channel receives the

difference signal from the summing circuit that compares the

average sensed current to the individual channel current.

When a power channel’s current is greater than the average

current, the signal applied via the summing correction circuit

to the comparator, reduces the output pulse width of the

comparator to compensate for the detected “above average”

current in that channel.

CURRENT

SENSING

COMPARATOR

PWM

CIRCUIT

+

RISEN1

+

CORRECTION

ERROR

AMPLIFIER

FB

REFERENCE

ISEN1

RIN

VCORE

Q3

Q4

L02

PHASE

PWM1

IL2

DAC

COUT

RLOAD

VIN

HIP6601B

-

Q1

Q2

L01

PHASE

IL1

VIN

HIP6601B

CURRENT

SENSING

COMPARATOR

PWM

CIRCUIT

CORRECTION

PWM2

-

I AVERAGE

+

+

+

-

PROGRAMMABLE

RISEN2

ISEN2

-

-

-

-

+

+

CURRENT

AVERAGING

FIGURE 1. SIMPLIFIED BLOCK DIAGRAM OF THE HIP6301V VOLTAGE AND CURRENT CONTROL LOOPS FOR 2-PHASE REGULATOR

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