hip6301vcbza-t Intersil Corporation, hip6301vcbza-t Datasheet - Page 13

• Manufacturer Part Number: hip6301vcbza-t
• Description: Microprocessor Core Voltage Regulator Multiphase Buck Pwm Controller
• Manufacturer: Intersil Corporation

Current Sensing and Balancing
Overview
The HIP6301V and HIP6302V sample the on-state voltage
drop across each synchronous MOSFET, Q2, as an
indication of the inductor current in that phase, see Figure 9.
Neglecting AC effects (to be discussed later), the voltage
drop across Q2 is simply r
Note that I
the total current (I
in use.
The voltage at Q2’s drain, the PHASE node, is applied to the
R
pin. This pin is held at virtual ground, so the current through
R
The I
following functions:
1. Detection of an overcurrent condition
2. Reduce the regulator output voltage with increasing load
3. Balance the I
ISEN
ISEN
current (droop)
ISEN
FB
resistor to develop the I
is
I
L
L
current provides information to perform the
, the inductor current, is either 1/2, 1/3, or 1/4 of
CURRENT
=
TO OVER
REFERENCE
AMPLIFIER
r
----------------------------------- -
FIGURE 9. SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM SHOWING CURRENT AND VOLTAGE SAMPLING
DS ON
RFB
ERROR
+
-
TRIP
L
DAC
R
LT
(
RIN
currents in multiple channels
ISEN
), depending on how many phases are
Cc
)
COMPARATOR
(
Q2
CHANNELS
TO OTHER
DS(ON)
)
.
COMP
13
ISEN
GENERATOR
SAWTOOTH
CORRECTION
+
+
-
(Q2) x inductor current (I
current through the ISEN
DIFFERENCE
-
REFERENCE
-
+
AVERAGING
HIP6301V, HIP6302V
HIP6301V, HIP6302V
COMPARATOR
+
-
HIP6301V
L
).
CURRENT
SENSING
CURRENT
SENSING
FROM
OTHER
CHANNELS
CIRCUIT
PWM
Over-Current, Selecting R
The current detected through the R
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 overcurrent
condition.
The nominal current through the R
50µA at full output load current, and the nominal trip point for
overcurrent detection is 165% of that value, or 82.5µA.
Therefore,
For a full load of 25A per phase, and an r
4mΩ, R
The overcurrent trip point would be 165% of 25A, or ~ 41A
per phase. The R
overcurrent trip point, but it is suggested to stay within ±25%
of nominal.
Droop, Selection of R
The average of the currents detected through the R
resistors is also steered to the FB pin. There is no DC return
path connected to the FB pin except for R
PWM
ISEN
ISEN
R
ISEN
= 2kΩ.
ONLY ONE OUTPUT
HIP6601
ISEN
=
( )r
--------------------------------------------- -
STAGE SHOWN
RISEN
I
L
value can be adjusted to change the
DS ON
CURRENT(S)
IN
50µA
CHANNELS
INDUCTOR
(
Q2
VIN
OTHER
ISEN
FROM
)
(
Q1
Q2
ISEN
PHASE
ISEN
)
.
L01
IL
resistor should be
resistor is averaged
DS(ON)
IN
, so the average
December 27, 2004
VCORE
(Q2) of
ISEN
FN9034.2