hip6602cb Intersil Corporation, hip6602cb Datasheet - Page 7

• Manufacturer Part Number: hip6602cb
• Description: Dual Channel Synchronous-rectified Buck Mosfet Driver
• Manufacturer: Intersil Corporation

PVCC and VCC pins. The bootstrap capacitor value in the
test circuit is 0.01PF.
The power dissipation approximation is a result of power
transferred to and from the upper and lower gates. But, the
internal bootstrap device also dissipates power on-chip
during the refresh cycle. Expressing this power in terms of
the upper MOSFET total gate charge is explained below.
The bootstrap device conducts when the lower MOSFET or
its body diode conducts and pulls the PHASE node toward
GND. While the bootstrap device conducts, a current path is
formed that refreshes the bootstrap capacitor. Since the
upper gate is driving a MOSFET, the charge removed from
the bootstrap capacitor is equivalent to the total gate charge
of the MOSFET. Therefore, the refresh power required by
the bootstrap capacitor is equivalent to the power used to
charge the gate capacitance of the upper MOSFETs.
where Q
capacitors and provided to the upper gate loads.
In Figure 1, C
is varied from 10kHz to 2MHz. PVCC and VCC are tied
together to a +12V supply.
Figure 2 shows the dissipation in the driver with 1nF loading
on both gates and each individually. Figure 3 is the same as
Figure 2 except the capacitance is increased to 3nF.
The impact of loading on power dissipation is shown in
Figure 4. Frequency is held constant while the gate
capacitors are varied from 1nF to 5nF. VCC and PVCC are
Typical Performance Curves
P
REFRESH
1200
1000
800
600
400
200
0
FIGURE 1. POWER DISSIPATION vs FREQUENCY
0
LOSS
C
C
U
U
=
= 4nF
= 5nF
= C
= C
U
f
SW
is the total charge removed from the bootstrap
L
and C
L
Q
LOSS
L
500
values are the same and frequency
V
FREQUENCY (kHz)
PVCC
C
C
U
U
= C
7
= C
=
L
C
= 3nF
L
= 1nF
f
U
SW
= 2nF
= C
Q
L
1000
U
V
PVCC
PVCC = 12V
VCC = 12V
1500
HIP6602
tied together and to a +12V supply. Figures 5 through 7
show the same characterization for PVCC tied to +5V
instead of +12V. The gate supply voltage, PVCC, within the
HIP6602 sets both upper and lower gate driver supplies at
the same 5V level for the last three curves.
Test Circuit
1200
1000
+12V
800
600
400
200
+5V OR +12V
0
0
0.15PF
C
L
PVCC = VCC = 12V
0.15PF
= 1nF, C
FIGURE 2. 1nF LOADING PROFILE
PWM1
PWM2
PGND
PVCC
+5V OR +12V
GND
VCC
C
U
= C
500
U
L
= 0nF
= 1nF
BOOT1
FREQUENCY (kHz)
0.01PF
UGATE2
PHASE2
UGATE1
PHASE1
BOOT2
LGATE2
LGATE1
0.01PF
1000
C
C
2N7002
2N7002
L
C
L
U
= 1nF, C
2N7002
1500
2N7002
L
= 0nF
100k:
100k:
C
C
U
U
2000