hip6301vcbza-t Intersil Corporation, hip6301vcbza-t Datasheet - Page 15

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

the sampled current (I
current (I
Where: I
Example: Using the previously given conditions, and
For I
Then I
As discussed previously, the voltage drop across each Q2
transistor at the point in time when current is sampled is
r
PHASE node, is applied through the R
HIP6301V ISEN pin. This pin is held at virtual ground, so the
current into ISEN is:
Example: From the previous conditions,
where I
I
r
Then: R
I
Short circuit I
Channel Frequency Oscillator
The channel oscillator frequency is set by placing a resistor,
R
showing the relationship between frequency, F
resistor R
to place this resistor next to the pin.
Layout Considerations
MOSFETs switch very fast and efficiently. The speed with
which the current transitions from one device to another
causes voltage spikes across the interconnecting
impedances and parasitic circuit elements. These voltage
spikes can degrade efficiency, radiate noise into the circuit
and lead to device overvoltage stress. Careful component
layout and printed circuit design minimizes the voltage
spikes in the converter. Consider, as an example, the turnoff
transition of the upper PWM MOSFET. Prior to turnoff, the
upper MOSFET was carrying channel current. During the
turnoff, current stops flowing in the upper MOSFET and is
picked up by the lower MOSFET. Any inductance in the
switched current path generates a large voltage spike during
the switching interval. Careful component selection, tight
SAMPLE
CURRENT TRIP
DSON
DS(ON)
T
, to ground from the FS/DIS pin. Figure 12 is a curve
LT
n = 4
SAMPLE
(Q2) x I
LT
ISEN
(Q2)
LT
= 100A,
T
LT
I
. To avoid pickup by the FS/DIS pin, it is important
SAMPLE
n = the number of channels
) by:
LT
= total load current
I
SENSE
R
SAMPLE
= 25.49A
ISEN
= 100A,
= 25.49A,
= 4mΩ
= 2.04K and
= 165%
= 165A.
=
=
----------------------------------------------------------------------------------- -
I
------- -
=
SAMPLE
LT
n
. The voltage at Q2’s drain, the
(
------------------------------------------------------------------ -
(
------------------------------------------------------------------ -
I
I
SAMPLE
+
SAMPLE
(
V
(
15
IN
6L
) can be related to the load
)V
) F
R
50µA
(
)r
CORE
)r
ISEN
DS ON
SW
DS ON
(
) V
(
ISEN
(
–
)
3V
IN
)
(
(
Q2
)
Q2
CORE
resistor to the
)
)
SW,
2
HIP6301V, HIP6302V
and
layout of the critical components, and short, wide circuit
traces minimize the magnitude of voltage spikes. Contact
Intersil for evaluation board drawings of the component
placement and printed circuit board.
There are two sets of critical components in a DC-DC
converter using a HIP6301V or HIP6302V controller and a
HIP6601 family gate driver. The power components are the
most critical because they switch large amounts of energy.
Next are small signal components that connect to sensitive
nodes or supply critical bypassing current and signal coupling.
The power components should be placed first. Locate the
input capacitors close to the power switches. Minimize the
length of the connections between the input capacitors, C
and the power switches. Locate the output inductors and
output capacitors between the MOSFETs and the load.
Locate the gate driver close to the MOSFETs.
The critical small components include the bypass capacitors
for VCC and PVCC on the gate driver ICs. Locate the bypass
capacitor, C
especially important to locate the resistors associated with the
input to the amplifiers close to their respective pins, since they
represent the input to feedback amplifiers. Resistor R
sets the oscillator frequency should also be located next to the
associated pin. It is especially important to place the R
resistor(s) at the respective ISEN terminals.
A multi-layer printed circuit board is recommended. Figure 13
shows the connections of the critical components for one output
channel of the converter. Note that capacitors C
could each represent numerous physical capacitors. Dedicate
one solid layer, usually the middle layer of the PC board, for a
ground plane and make all critical component ground connections
1,000
500
200
100
50
20
10
5
2
1
10
FIGURE 12. RESISTANCE R
20
CHANNEL OSCILLATOR FREQUENCY, FSW (kHz)
BP
, for the controller close to the device. It is
50
100
200
500 1,000
T
vs FREQUENCY
2,000
IN
and C
December 27, 2004
5,000 10,000
T
OUT
, that
SEN
FN9034.2
IN
,