HIP6012EVAL1 Intersil, HIP6012EVAL1 Datasheet - Page 5

• Manufacturer Part Number: HIP6012EVAL1
• Description: EVAL BOARD DISK DRIVE SUPPLY
• Manufacturer: Intersil

Specifications of HIP6012EVAL1

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.3 ~ 12V
• Current - Output: 25A
• Voltage - Input: 2.5 ~ 12 V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: HIP6012
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -
• Frequency - Switching: -

PGND (Pin 11)
This is the power ground connection. Tie the lower MOSFET
source to this pin.
LGATE (Pin 12)
Connect LGATE to the lower MOSFET gate. This pin
provides the gate drive for the lower MOSFET.
PVCC (Pin 13)
Provide a bias supply for the lower gate drive to this pin.
VCC (Pin 14)
Provide a 12V bias supply for the chip to this pin.
Functional Description
Initialization
The HIP6012 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 and the enable (EN) pin. The POR
monitors the bias voltage at the VCC pin and the input
voltage (V
equal to V
protection). With the EN pin held to V
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.
The Power-On Reset (POR) function inhibits operation with
the chip disabled (EN pin low). With both input supplies
above their POR thresholds, transitioning the EN pin high
initiates a soft start interval.
Soft Start
The POR function initiates the soft start sequence. An
internal 10µA 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
error amplifier (COMP pin) controls the converter’s output
voltage. At t1 in Figure 3, the SS voltage reaches the valley
of the 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 t2. With sufficient
output voltage, the clamp on the reference input controls
the output voltage. This is the interval between t2 and t3 in
Figure 3. At t3 the SS voltage exceeds the reference
voltage and the output voltage is in regulation. This method
provides a rapid and controlled output voltage rise.
SS
) on the SS pin to 4V. Soft start clamps the error
IN
IN
) on the OCSET pin. The level on OCSET is
Less a fixed voltage drop (see overcurrent
SS
IN
= 0.1µF. Initially the clamp on the
and V
5
CC
are equivalent and the
CC
, the POR function
CC
threshold
HIP6012
Overcurrent Protection
The overcurrent 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.
The overcurrent function cycles the soft-start function in a
hiccup mode to provide fault protection. A resistor (R
programs the overcurrent trip level. An internal 200µA
(typical) current sink develops a voltage across R
is reference to V
MOSFET (also referenced to V
across R
sequence. The soft-start function discharges C
10µA current sink and inhibits PWM operation. The soft-start
function recharges C
the error amplifier clamped to the SS voltage. Should an
overload occur while recharging C
inhibits PWM operation while fully charging C
DS(ON)
0V
0V
15A
10A
4V
2V
0V
5A
0A
to monitor the current. This method enhances the
OCSET
FIGURE 4. OVERCURRENT OPERATION
FIGURE 3. SOFT-START INTERVAL
, the overcurrent function initiates a soft-start
IN
SOFT-START
(1V/DIV.)
. When the voltage across the upper
SS
t1
, and PWM operation resumes with
TIME (5ms/DIV.)
TIME (20ms/DIV.)
IN
t2
) exceeds the voltage
SS
OUTPUT
VOLTAGE
(1V/DIV.)
, the soft start function
t3
SS
December 27, 2004
SS
OCSET
to 4V to
with a
OCSET
FN4324.2
that
)