HIP6303CB Просмотр технического описания (PDF) - Intersil

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HIP6303CB

Microprocessor CORE Voltage Regulator Multi-Phase Buck PWM Controller

Intersil 

HIP6303

RIN

RFB Cc

FB

COMP

HIP6303

ERROR

AMPLIFIER

-

+

SAWTOOTH

GENERATOR

CORRECTION

+

-

COMPARATOR

-

PWM

+

CIRCUIT

REFERENCE

DAC

DIFFERENCE

+

-

TO OTHER

CHANNELS

CURRENT

SENSING

CURRENT

SENSING

FROM

OTHER

CHANNELS

AVERAGING

PWM

ISEN

TO OVER

+

CURRENT

TRIP

-

COMPARATOR

REFERENCE

VIN

Q1 L01

HIP6601

Q2

IL

PHASE

RISEN

ONLY ONE OUTPUT

STAGE SHOWN

INDUCTOR

CURRENT(S)

FROM

OTHER

CHANNELS

VCORE

FIGURE 7. SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM SHOWING CURRENT AND VOLTAGE SAMPLING

Current Sensing and Balancing

Overview

The HIP6303 samples the on-state voltage drop across each

synchronous rectifier FET, Q2, as an indication of the

inductor current in that channel, see Figure 7. Neglecting AC

effects (to be discussed later), the voltage drop across Q2 is

simply rDS(ON)(Q2) x inductor current (IL). Note that IL, the

inductor current, is either 1/2, 1/3, or 1/4 of the total current

(ILT), depending on how many channels are active.

The voltage at Q2’s drain, the PHASE node, is applied to the

RISEN resistor to develop the IISEN current to the HIP6303

ISEN pin. This pin is held at virtual ground, so the current

through RISEN is IL x rDS(ON)(Q2) / RISEN.

The IISEN current provides information to perform the

following functions:

1. Detection of an over-current condition

2. Reduce the regulator output voltage with increasing load

current (droop)

3. Balance the IL currents in multiple channels

Over-Current, Selecting RISEN

The current detected through the RISEN resistor is averaged

with the current(s) detected in the other 1, 2, or 3 channels.

The averaged current is compared with a trimmed, internally

generated current, and used to detect an over-current

condition.

The nominal current through the RISEN resistor should be

50µA at full output load current, and the nominal trip point for

over-current detection is 165% of that value, or 82.5µA.

Therefore, RISEN = IL x rDS(ON) (Q2) / 50µA.

For a full load of 25A per channel, and an rDS(ON) (Q2) of

4mΩ, RISEN = 2kΩ.

The over-current trip point would be 165% of 25A, or ~ 41A

per channel. The RISEN value can be adjusted to change the

over-current trip point, but it is suggested to stay within ±25%

of nominal.

11

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