HIP6311ACB Intersil, HIP6311ACB Datasheet - Page 11

• Manufacturer Part Number: HIP6311ACB
• Description: IC CTRLR PWM MULTIPHASE 20-SOIC
• Manufacturer: Intersil

Specifications of HIP6311ACB

• Pwm Type: Controller
• Number Of Outputs: 4
• Frequency - Max: 1.5MHz
• Voltage - Supply: 4.75 V ~ 5.25 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 20-SOIC (7.5mm Width)
• Frequency-max: 1.5MHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Duty Cycle: -

Current Sensing and Balancing
Overview
The HIP6311A samples the on-state voltage drop across
each synchronous rectifier FET, Q2, as an indication of the
inductor current in that phase, 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:
Over-Current, Selecting R
The current detected through the R
with the current(s) detected in the other 1, 2, or 3 channels. The
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 phases are in use.
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
ISEN
CORRECTION
+
+
-
ISEN
current to the HIP6311A
DIFFERENCE
-
ISEN
resistor is averaged
L
). Note that I
REFERENCE
.
-
+
AVERAGING
COMPARATOR
+
-
L
, the
HIP6311A
HIP6311A
HIP6311A
CURRENT
SENSING
CURRENT
SENSING
FROM
OTHER
CHANNELS
CIRCUIT
PWM
averaged current is compared with a trimmed, internally gener-
ated current, and used to detect an over-current condition.
The nominal current through the R
50µA at full output load current, and the nominal trip point for
over-current detection is 165% of that value, or 82.5µA.
Therefore, R
For a full load of 25A per phase, and an r
4mΩ, R
The over-current trip point would be 165% of 25A, or ~ 41A
per phase. The R
over-current 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
current creates a voltage drop across R
increases the apparent V
current, causing the system to decrease V
balance at the FB pin. This is the desired “droop” voltage used
to maintain V
With a high dv/dt load transient, typical of high performance
microprocessors, the largest deviations in output voltage
PWM
ISEN
I
SEN
ISEN
= 2kΩ.
CORE
ONLY ONE OUTPUT
HIP6601
ISEN
= I
within limits under transient conditions.
L
STAGE SHOWN
R
x r
ISEN
value can be adjusted to change the
CORE
CURRENT(S)
DS(ON)
IN
CHANNELS
INDUCTOR
Q2
V
IN
OTHER
FROM
voltage with increasing load
Q1
(Q2) / 50µA.
ISEN
PHASE
L
I
01
L
IN
resistor should be
IN
. This drop
DS(ON)
CORE
, so the average
V
to maintain
CORE
(Q2) of
ISEN