HIP6005 INTERSIL [Intersil Corporation], HIP6005 Datasheet - Page 5

• Manufacturer Part Number: HIP6005
• Description: Buck Pulse-Width Modulator (PWM) Controller and Output Voltage Monitor
• Manufacturer: INTERSIL [Intersil Corporation]

BOOT (Pin 15)
This pin provides bias voltage to the upper MOSFET driver.
A bootstrap circuit may be used to create a BOOT voltage
suitable to drive a standard N-Channel MOSFET.
NC (Pin 16)
No connection.
NC (Pin 17)
No connection.
VCC (Pin 18)
Provide a 12V bias supply for the chip to this pin.
OVP (Pin 19)
The OVP pin can be used to drive an external SCR in the
event of an overvoltage condition.
RT (Pin 20)
This pin provides oscillator switching frequency adjustment.
By placing a resistor (R
200kHz switching frequency is increased according to the
following equation:
Conversely, connecting a pull-up resistor (R
to V
following equation:
Functional Description
Initialization
The HIP6005 automatically initializes upon receipt of power.
Special sequencing of the input supplies is not necessary.
The Power-On Reset (POR) function continually monitors
the input supply voltages. The POR monitors the bias
voltage at the VCC pin and the input voltage (V
OCSET pin. The level on OCSET is equal to V
voltage drop (see over-current protection). The POR function
initiates soft start operation after both input supply voltages
exceed their POR thresholds. For operation with a single
+12V power source, V
+12V power source must exceed the rising V
before POR initiates operation.
Soft Start
The POR function initiates the soft start sequence. An
internal 10 A current source charges an external capacitor
(C
amplifier output (COMP pin) and reference input (+ terminal
of error amp) to the SS pin voltage. Figure 3 shows the soft
start interval with C
amplifier (COMP pin) controls the converter’s output voltage.
At t
Fs 200kHz
Fs 200kHz
SS
1
CC
) on the SS pin to 4V. Soft start clamps the error
in Figure 3, the SS voltage reaches the valley of the
reduces the switching frequency according to the
+
–
-------------------- -
R
-------------------- -
R
5 10
4 10
T
T
k
k
SS
7
6
= 0.1 F. Initially the clamp on the error
IN
T
) from this pin to GND, the nominal
and V
(R
(R
T
T
to 12V)
to GND)
5
CC
are equivalent and the
T
) from this pin
CC
IN
IN
threshold
less a fixed
) on the
HIP6005
oscillator’s triangle wave. The oscillator’s triangular
waveform is compared to the ramping error amplifier voltage.
This generates PHASE pulses of increasing width that
charge the output capacitor(s). This interval of increasing
pulse width continues to t
the clamp on the reference input controls the output voltage.
This is the interval between t
voltage exceeds the DACOUT voltage and the output
voltage is in regulation. This method provides a rapid and
controlled output voltage rise. The PGOOD signal toggles
‘high’ when the output voltage (VSEN pin) is within 5% of
DACOUT. The 2% hysteresis built into the power good
comparators prevents PGOOD oscillation due to nominal
output voltage ripple.
Over-Current Protection
The over-current function protects the converter from a
shorted output by using the upper MOSFETs on-resistance,
r
converter’s efficiency and reduces cost by eliminating a
current sensing resistor.
DS(ON)
0V
0V
0V
15A
10A
5A
0A
4V
2V
0V
to monitor the current. This method enhances the
FIGURE 4. OVER-CURRENT OPERATION
SOFT-START
FIGURE 3. SOFT START INTERVAL
(1V/DIV.)
t
1
TIME (5ms/DIV.)
TIME (20ms/DIV.)
2
(2V/DIV.)
PGOOD
. With sufficient output voltage,
2
t
2
and t
3
in Figure 3. At t
t
3
OUTPUT
VOLTAGE
(1V/DIV.)
3
the SS