HIP6013 Intersil Corporation, HIP6013 Datasheet - Page 9

• Manufacturer Part Number: HIP6013
• Description: Buck Pulse-Width Modulator (PWM) Controller
• Manufacturer: Intersil Corporation

operation, select the bulk capacitor with voltage and current
ratings above the maximum input voltage and largest RMS
current required by the circuit. The capacitor voltage rating
should be at least 1.25 times greater than the maximum
input voltage and a voltage rating of 1.5 times is a
conservative guideline. The RMS current rating requirement
for the input capacitor of a buck regulator is approximately
1/2 the DC load current.
For a through hole design, several electrolytic capacitors
(Panasonic HFQ series or Nichicon PL series or Sanyo MV-
GX or equivalent) may be needed. For surface mount
designs, solid tantalum capacitors can be used, but caution
must be exercised with regard to the capacitor surge current
rating. These capacitors must be capable of handling the
surge-current at power-up. The TPS series available from
AVX, and the 593D series from Sprague are both surge
current tested.
MOSFET Selection/Considerations
The HIP6013 requires an N-Channel power MOSFET. It
should be selected based upon r
requirements, and thermal management requirements.
In high-current applications, the MOSFET power
dissipation, package selection and heatsink are the
dominant design factors. The power dissipation includes
two loss components; conduction loss and switching loss.
The conduction losses are the largest component of power
dissipation for the MOSFET. Switching losses also
contribute to the overall MOSFET power loss (see the
equations below). These equations assume linear voltage-
current transitions and are approximations. The gate-
charge losses are dissipated by the HIP6013 and don't
heat the MOSFET. However, large gate-charge increases
the switching interval, t
MOSFET switching losses. Ensure that the MOSFET is
within its maximum junction temperature at high ambient
temperature by calculating the temperature rise according
to package thermal-resistance specifications. A separate
heatsink may be necessary depending upon MOSFET
power, package type, ambient temperature and air flow.
P
Where: D is the duty cycle = V
P
SW
COND
=
1
2 I
t
Fs is the switching frequency.
= I
SW
O
O
2
is the switching interval, and
x V
x r
IN
DS(ON)
x t
SW
SW
x D
x Fs
2-170
, which increases the upper
O
/ V
IN
,
DS(ON)
, gate supply
HIP6013
Standard-gate MOSFETs are normally recommended for
use with the HIP6013. However, logic-level gate MOSFETs
can be used under special circumstances. The input voltage,
upper gate drive level, and the MOSFET’s absolute gate-to-
source voltage rating determine whether logic-level
MOSFETs are appropriate.
Figure 9 shows the upper gate drive (BOOT pin) supplied by
a bootstrap circuit from V
develops a floating supply voltage referenced to the PHASE
pin. This supply is refreshed each cycle to a voltage of V
less the boot diode drop (V
turns on. A logic-level MOSFET can only be used for Q1 if
the MOSFET’s absolute gate-to-source voltage rating
exceeds the maximum voltage applied to V
Figure 10 shows the upper gate drive supplied by a direct
connection to VCC. This option should only be used in
converter systems where the main input voltage is +5VDC
or less. The peak upper gate-to-source voltage is
approximately V
power and +12VDC for the bias, the gate-to-source voltage
of Q1 is 7V. A logic-level MOSFET is a good choice for Q1
and a logic-level MOSFET is a good choice for Q1 under
these conditions.
HIP6013
FIGURE 9. UPPER GATE DRIVE - BOOTSTRAP OPTION
+
-
+12V
VCC
CC
GND
D
BOOT
BOOT
UGATE
PHASE
less the input supply. For +5V main
CC
D
C
. The boot capacitor, C
) when the lower MOSFET, Q2
BOOT
+5V OR +12V
Q1
D2
CC
NOTE:
V
.
G-S
BOOT
V
CC
- V
CC
D