hip6303cbz-t Intersil Corporation, hip6303cbz-t Datasheet - Page 11

• Manufacturer Part Number: hip6303cbz-t
• Description: Microprocessor Core Voltage Regulator Multiphase Buck Pwm Controller
• Manufacturer: Intersil Corporation

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 r
inductor current, is either 1/2, 1/3, or 1/4 of the total current
(I
The voltage at Q2’s drain, the PHASE node, is applied to the
R
ISEN pin. This pin is held at virtual ground, so the current
through R
The I
following functions:
1. Detection of an over-current condition
2. Reduce the regulator output voltage with increasing load
3. Balance the I
LT
ISEN
), depending on how many channels are active.
current (droop)
ISEN
FB
resistor to develop the I
DS(ON)
ISEN
current provides information to perform the
CURRENT
TO OVER
REFERENCE
AMPLIFIER
FIGURE 7. SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM SHOWING CURRENT AND VOLTAGE SAMPLING
(Q2) x inductor current (I
is I
R
ERROR
+
-
TRIP
FB
L
DAC
R
L
currents in multiple channels
IN
x r
C
COMPARATOR
DS(ON)
c
CHANNELS
TO OTHER
COMP
11
(Q2) / R
GENERATOR
ISEN
SAWTOOTH
CORRECTION
+
+
-
current to the HIP6303
DIFFERENCE
-
ISEN
L
). Note that I
REFERENCE
-
.
+
AVERAGING
COMPARATOR
+
-
L
, the
HIP6303
HIP6303
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 over-current
condition.
The nominal current through the R
50 A at full output load current, and the nominal trip point for
over-current detection is 165% of that value, or 82.5 A.
Therefore, R
For a full load of 25A per channel, and an r
4m , R
The over-current trip point would be 165% of 25A, or ~ 41A
per channel. The R
over-current trip point, but it is suggested to stay within 25%
of nominal.
PWM
ISEN
I
SEN
ISEN
= 2k .
ONLY ONE OUTPUT
HIP6601
= I
ISEN
L
STAGE SHOWN
R
x r
ISEN
value can be adjusted to change the
DS(ON)
CURRENT(S)
CHANNELS
INDUCTOR
Q2
V
IN
OTHER
ISEN
FROM
Q1
(Q2) / 50 A.
ISEN
PHASE
ISEN
L
I
01
L
resistor should be
resistor is averaged
DS(ON)
V
CORE
(Q2) of