HIP6500BEVAL1 INTERSIL [Intersil Corporation], HIP6500BEVAL1 Datasheet - Page 13

• Manufacturer Part Number: HIP6500BEVAL1
• Description: Multiple Linear Power Controller with ACPI Control Interface
• Manufacturer: INTERSIL [Intersil Corporation]

Transistor Selection/Considerations
The HIP6500B usually requires one P-Channel (or bipolar
PNP), two N-Channel MOSFETs and two bipolar NPN
transistors.
One important criteria for selection of transistors for all the
linear regulators/switching elements is package selection for
efficient removal of heat. The power dissipated in a linear
regulator/switching element is
Select a package and heatsink that maintains the junction
temperature below the rating with the maximum expected
ambient temperature.
Q1
The active element on the 2.5V/3.3V
different requirements for each of the two voltage settings. In
2.5V systems utilizing RDRAM (or voltage-compatible)
memory, Q1 has to be a bipolar NPN capable of conducting
up to 7.5A and exhibit a current gain (h
this current and 0.7V V
is actively regulated while in active state. In 3.3V systems
(SDRAM or compatible) Q1 has to be an N-Channel
MOSFET; in such systems the MOSFET is switched on
during active state (S0, S1). The main criteria for the
selection of this transistor is output voltage budgeting. The
maximum r
can be expressed with the following equation:
r
V
V
I
The gate bias available for this MOSFET is of the order of 8V.
OUTmax
P
DS ON max
OUTmin
INmin
LINEAR
- minimum input voltage
- maximum output current
- minimum output voltage allowed
=
DS(ON)
I
=
O
V
-------------------------------------------------- -
INmin
V
IN
allowed at highest junction temperature
I
OUTmax
–
–
V
CE
V
OUT
OUTmin
; in such systems the 2.5V output
13
, where
MEM
fe
) of minimum 40 at
output has
HIP6500B
Q5
If a P-Channel MOSFET is used to switch the 5VSB output
of the ATX supply into the 5V
states (as dictated by EN5VDL status), then, similar to the
situation where Q1 is a MOSFET, the selection criteria of this
device is also proper voltage budgeting. The maximum
r
so a logic level MOSFET needs to be selected. If a PNP
device is chosen to perform this function, it has to have a low
saturation voltage while providing the maximum sleep
current and have a current gain sufficiently high to be
saturated using the minimum drive current (typically 20mA).
Q3, Q4
The two N-Channel MOSFETs are used to switch the 3.3V
and 5V inputs provided by the ATX supply into the
3.3VDUAL and 5VDUAL outputs, respectively, while in active
(S0, S1) state. Similar r
as well. Unlike the PMOS, however, these NMOS transistors
get the benefit of an increased V
and 7V, respectively).
Q2
The NPN transistor used as sleep state pass element (Q2)
on the 3.3V
of 100 at 1.5V V
operating temperature range.
DS(ON)
, however, has to be achieved with only 4.5V of V
DUAL
CE
output has to have a minimum current gain
and 500mA I
DS(ON)
DUAL
criteria apply in these cases
GS
CE
output during S3 and S5
drive (approximately 8V
throughout the in-circuit
GS
,