INTERSIL HIP6018B

HIP6018B
Data Sheet
Advanced PWM and Dual Linear Power
Control
The HIP6018B provides the power control and protection for
three output voltages in high-performance microprocessor
and computer applications. The IC integrates a PWM
controllers, a linear regulator and a linear controller as well
as the monitoring and protection functions into a single
package. The PWM controller regulates the microprocessor
core voltage with a synchronous-rectified buck converter.
The linear controller regulates power for the GTL bus and
the linear regulator provides power for the clock driver circuit.
The HIP6018B includes an Intel-compatible, TTL 5-input
digital-to-analog converter (DAC) that adjusts the core PWM
output voltage from 2.1VDC to 3.5VDC in 0.1V increments
and from 1.3VDC to 2.05VDC in 0.05V steps. The precision
reference and voltage-mode control provide ±1% static
regulation. The linear regulator uses an internal pass device
to provide 2.5V ±2.5%. The linear controller drives an
external N-channel MOSFET to provide 1.5V ±2.5%.
The HIP6018B monitors all the output voltages. A single
Power Good signal is issued when the core is within 10% of
the DAC setting and the other levels are above their undervoltage levels. Additional built-in over-voltage protection for
the core output uses the lower MOSFET to prevent output
voltages above 115% of the DAC setting. The PWM overcurrent function monitors the output current by using the
voltage drop across the upper MOSFET’s rDS(ON),
eliminating the need for a current sensing resistor.
May 1999
File Number
4586.1
Features
• Provides 3 Regulated Voltages
- Microprocessor Core, Clock and GTL Power
• Drives N-Channel MOSFETs
• Operates from +3.3V, +5V and +12V Inputs
• Simple Single-Loop PWM Control Design
- Voltage-Mode Control
• Fast Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Ratios
• Excellent Output Voltage Regulation
- Core PWM Output: ±1% Over Temperature
- Other Outputs: ±2.5% Over Temperature
• TTL-Compatible 5-Bit Digital-to-Analog Core Output
Voltage Selection
- Wide Range . . . . . . . . . . . . . . . . . . . 1.3VDC to 3.5VDC
- 0.1V Steps . . . . . . . . . . . . . . . . . . . . 2.1VDC to 3.5VDC
- 0.05V Steps . . . . . . . . . . . . . . . . . . 1.3VDC to 2.05VDC
• Power-Good Output Voltage Monitor
• Microprocessor Core Voltage Protection Against Shorted
MOSFET
• Over-Voltage and Over-Current Fault Monitors
- Does Not Require Extra Current Sensing Element,
Uses MOSFET’s rDS(ON)
• Small Converter Size
- Constant Frequency Operation
- 200kHz Free-Running Oscillator; Programmable from
50kHz to over 1MHz
Pinout
HIP6018B
(SOIC)
TOP VIEW
Applications
VCC 1
24 UGATE1
VID4 2
23 PHASE1
VID3 3
22 LGATE1
VID2 4
21 PGND
VID1 5
20 OCSET1
VID0 6
19 VSEN1
• Full Motherboard Power Regulation for Computers
• Low-Voltage Distributed Power Supplies
Ordering Information
PART NUMBER
TEMP.
RANGE (oC)
PACKAGE
PKG.
NO.
18 FB1
PGOOD 7
17 COMP1
FAULT 8
SS 9
16 FB3
RT 10
15 DRIVE3
HIP6018BCB
0 to 70
24 Ld SOIC
M24.3
14 GND
FB2 11
13 VOUT2
VIN2 12
2-238
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
www.intersil.com or 407-727-9207 | Copyright © Intersil Corporation 1999
FAULT
FB2
VOUT2
VIN2
DRIVE3
FB3
0.23A
3V
+
-
+
-
+
-
+
0.3V
SS
1.26V
VCC
INHIBIT
+
2-239
-
FIGURE 1.
4V
OV
DACOUT
SOFTSTART
& FAULT
LOGIC
TTL D/A
CONVERTER
(DAC)
OC2
LUV
VID4
VID0
VID2
VID1
VID3
11µA
+
-
+
-
LINEAR
UNDERVOLTAGE
+
-
+
-
+
-
+
-
FB1
OC1
COMP1
ERROR
AMP
115%
90%
110%
VSEN1
PWM
RT
UPPER
DRIVE
RESET (POR)
POWER-ON
VCC
LOWER
DRIVE
GATE
CONTROL
INHIBIT
OSCILLATOR
PWM
COMP
+
-
+
-
200mA
OCSET1
VCC
VCC
3V
GND
PGND
LGATE1
PHASE1
UGATE1
PGOOD
HIP6018B
Block Diagram
HIP6018B
Simplified Power System Diagram
+5VIN
Q1
+3.3VIN
LINEAR
REGULATOR
VOUT2
PWM1
CONTROLLER
VOUT1
HIP6018B
Q2
LINEAR
CONTROLLER
Q3
VOUT3
FIGURE 2.
Typical Application
+12VIN
+5VIN
CIN
VCC
OCSET1
VIN2
+3.3VIN
POWERGOOD
PGOOD
VOUT2
VOUT2
2.5V
UGATE1
FB2
COUT2
Q1
PHASE1
LGATE1
Q3
Q2
CR1
PGND
DRIVE3
HIP6018B
VOUT3
FB3
VSEN1
1.5V
FB1
COUT3
COMP1
VID0
VID1
VID2
FAULT
VID3
RT
VID4
SS
GND
FIGURE 3.
2-240
LOUT1
CSS
COUT1
VOUT1
1.3V TO 3.5V
HIP6018B
Absolute Maximum Ratings
Thermal Information
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +15V
PGOOD, RT, FAULT, and GATE Voltage . . . GND - 0.3V to VCC + 0.3V
Input, Output or I/O Voltage . . . . . . . . . . . . . . . . . . GND -0.3V to 7V
Thermal Resistance (Typical, Note 1)
θJA (oC/W)
SOIC Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75
SOIC Package (with 3 in2 of copper) . . . . . . . . . . .
65
Maximum Junction Temperature (Plastic Package) . . . . . . . .150oC
Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . .300oC
(SOIC - Lead Tips Only)
Operating Conditions
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . +12V ±10%
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . 0oC to 70oC
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . 0oC to 125oC
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
1. θJA is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
Recommended Operating Conditions, Unless Otherwise Noted. Refer to Figures 1, 2 and 3
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
-
8
-
mA
VCC SUPPLY CURRENT
Nominal Supply
ICC
UGATE1, DRIVE3, LGATE1, and VOUT2 Open
POWER-ON RESET
Rising VCC Threshold
VOCSET = 4.5V
8.6
-
10.4
V
Falling VCC Threshold
VOCSET = 4.5V
8.2
-
10.2
V
2.45
2.55
2.65
V
VIN2 Under-Voltage Hysteresis
-
100
-
mV
Rising VOCSET1 Threshold
-
1.25
-
V
Rising VIN2 Under-Voltage Threshold
OSCILLATOR
Free Running Frequency
RT = OPEN
185
200
215
kHz
Total Variation
6kΩ < RT to GND < 200kΩ
-15
-
+15
%
-
1.9
-
VP-P
DAC(VID0-VID4) Input Low Voltage
-
-
0.8
V
DAC(VID0-VID4) Input High Voltage
2.0
-
-
V
DACOUT Voltage Accuracy
-1.0
-
+1.0
%
1.240
1.265
1.290
V
-2.5
-
2.5
%
-
75
87
%
-
6
-
%
Over-Current Protection
180
230
-
mA
Over-Current Protection During Start-Up
560
700
-
mA
-2.5
-
2.5
%
-
75
87
%
-
6
-
%
VIN2 - VOUT3 > 1.5V
20
40
-
mA
VIN2 - DRIVE3 > 0.6V
20
40
-
mA
∆VOSC
Ramp Amplitude
RT = Open
REFERENCE AND DAC
Reference Voltage (Pin FB2 and FB3)
LINEAR REGULATOR
Regulation
10mA < IVOUT2 < 150mA
Under-Voltage Level
FB2UV
FB2 Rising
Under-Voltage Hysteresis
LINEAR CONTROLLER
Regulation
VSEN3 = DRIVE3, 0 < IDRIVE3 < 20mA
Under-Voltage Level
FB3UV
FB3 Rising
Under-Voltage Hysteresis
Output Drive Current
IDRIVE3
DRIVE3 Source Current
2-241
HIP6018B
Electrical Specifications
Recommended Operating Conditions, Unless Otherwise Noted. Refer to Figures 1, 2 and 3 (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
-
88
-
dB
-
15
-
MHz
COMP = 10pF
-
6
-
V/µs
PWM CONTROLLER ERROR AMPLIFIER
DC Gain
Gain-Bandwidth Product
GBWP
Slew Rate
SR
PWM CONTROLLER GATE DRIVER
Upper Drive Source
IUGATE
VCC = 12V, VUGATE1 (or VGATE2) = 6V
-
1
-
A
Upper Drive Sink
RUGATE
VUGATE1-PHASE1 = 1V
-
1.7
3.5
Ω
Lower Drive Source
ILGATE
VCC = 12V, VLGATE1 = 1V
-
1
-
A
Lower Drive Sink
RLGATE
VLGATE1 = 1V
-
1.4
3.0
Ω
VSEN1 Rising
112
115
118
%
VFAULT = 10V
10
14
-
mA
VOCSET = 4.5VDC
170
200
230
µA
-
11
-
µA
-
-
1.0
V
PROTECTION
VOUT1 Over-Voltage Trip
FAULT Sourcing Current
IOVP
OCSET1 Current Source
IOCSET
Soft-Start Current
ISS
Chip Shutdown Soft-Start Threshold
POWER GOOD
VOUT1 Upper Threshold
VSEN1 Rising
108
-
110
%
VOUT1 Under Voltage
VSEN1 Rising
92
-
94
%
VOUT1 Hysteresis (VSEN1 / DACOUT)
Upper/Lower Threshold
-
2
-
%
IPGOOD = -4mA
-
-
0.5
V
PGOOD Voltage Low
VPGOOD
Typical Performance Curves
100
CGATE = 4800pF
CUGATE1 = CLGATE1 = CGATE
VVCC = 12V, VIN = 5V
80
RT PULLUP
TO +12V
ICC (mA)
RESISTANCE (kΩ)
1000
100
10
60
CGATE = 3600pF
40
CGATE = 1500pF
20
RT PULLDOWN TO VSS
CGATE = 660pF
0
10
100
SWITCHING FREQUENCY (kHz)
FIGURE 4. RT RESISTANCE vs FREQUENCY
2-242
1000
100
200
300
400
500
600
700
800
900 1000
SWITCHING FREQUENCY (kHz)
FIGURE 5. BIAS SUPPLY CURRENT vs FREQUENCY
HIP6018B
Functional Pin Description
UGATE1 (Pin 24)
VSEN1 (Pin 19)
Connect UGATE pin to the PWM converter’s upper MOSFET
gate. This pin provides the gate drive for the upper MOSFET.
This pin is connected to the PWM converter’s output voltage.
The PGOOD and OVP comparator circuits use this signal to
report output voltage status and for over voltage protection.
PGND (Pin 21)
OCSET1 (Pin 20)
Connect a resistor (ROCSET) from this pin to the drain of the
upper MOSFET. ROCSET, an internal 200µA current source
(IOCSET), and the upper MOSFET on-resistance (rDS(ON))
set the PWM converter over-current (OC) trip point
according to the following equation:
I OCSET × R OCSET
I PEAK = ---------------------------------------------------r DS ( ON )
An over-current trip cycles the soft-start function. Sustaining
an over-current for 2 soft-start intervals shuts down the
controller.
SS (Pin 9)
Connect a capacitor from this pin to ground. This capacitor,
along with an internal 11µA (typically) current source, sets
the soft-start interval of the converter. Pulling this pin low
with an open drain signal will shut down the IC.
VID0, VID1, VID2, VID3, VID4 (Pins 6, 5, 4, 3 and 2)
VID0-4 are the input pins to the 5-bit DAC. The states of
these five pins program the internal voltage reference
(DACOUT). The level of DACOUT sets the core converter
output voltage. It also sets the core PGOOD and OVP
thresholds.
COMP1 and FB1 (Pins 17 and 18)
COMP1 and FB1 are the available external pins of the PWM
error amplifier. The FB1 pin is the inverting input of the error
amplifier. Similarly, the COMP1 pin is the error amplifier
output. These pins are used to compensate the voltagecontrol feedback loop of the PWM converter.
GND (Pin 14)
Signal ground for the IC. All voltage levels are measured with
respect to this pin.
This is the power ground connection. Tie the PWM
converter’s lower MOSFET source to this pin.
LGATE1 (Pin 22)
Connect LGATE1 to the PWM converter’s lower MOSFET
gate. This pin provides the gate drive for the lower MOSFET.
VCC (Pin 1)
Provide a 12V bias supply for the IC to this pin. This pin
also provides the gate bias charge for all the MOSFETs
controlled by the IC.
RT (Pin 10)
This pin provides oscillator switching frequency adjustment.
By placing a resistor (RT) from this pin to GND, the nominal
200kHz switching frequency is increased according to the
following equation:
6
5 × 10
Fs ≈ 200kHz + --------------------R T ( kΩ )
(RT to GND)
Conversely, connecting a pull-up resistor (RT) from this pin
to VCC reduces the switching frequency according to the
following equation:
7
4 × 10
Fs ≈ 200kHz – --------------------R T ( kΩ )
(RT to 12V)
FAULT (Pin 8)
This pin is low during normal operation, but it is pulled to VCC
in the event of an over-voltage or over-current condition.
DRIVE3 (Pin 15)
Connect this pin to the gate of an external MOSFET. This pin
provides the drive for the linear controller’s pass transistor.
FB3 (Pin 16)
Connect this pin to a resistor divider to set the linear
controller output voltage.
VOUT2 (Pin 13)
PGOOD (Pin 7)
Output of the linear regulator. Supplies current up to 230mA.
PGOOD is an open collector output used to indicate the
status of the output voltages. This pin is pulled low when the
core output is not within ±10% of the DACOUT reference
voltage and the other outputs are below their under-voltage
thresholds. The PGOOD output is open for ‘11111’ VID
code. See Table 1.
FB2 (Pin 11)
PHASE1 (Pin 23)
Connect the PHASE pin to the PWM converter’s upper
MOSFET source. This pin is used to monitor the voltage
drop across the upper MOSFET for over-current protection.
2-243
Connect this pin to a resistor divider to set the linear
regulator output voltage.
VIN2 (Pin 12)
This pin supplies power to the internal regulator. Connect
this pin to a suitable 3.3V source.
Additionally, this pin is used to monitor the 3.3V supply. If,
following a startup cycle, the voltage drops below 2.55V
(typically), the chip shuts down. A new soft-start cycle is
initiated upon return of the 3.3V supply above the under-voltage
threshold.
HIP6018B
Description
Operation
The HIP6018B monitors and precisely controls 4 output
voltage levels (Refer to Figures 1, 2, and 3). It is designed for
microprocessor computer applications with 3.3V and 5V
power, and 12V bias input from an ATX power supply. The IC
has one PWM controller, a linear controller, and a linear
regulator. The PWM controller is designed to regulate the
microprocessor core voltage (VOUT1) by driving 2 MOSFETs
(Q1 and Q2) in a synchronous-rectified buck converter
configuration. The core voltage is regulated to a level
programmed by the 5-bit digital-to-analog converter (DAC).
An integrated linear regulator supplies the 2.5V clock power
(VOUT2). The linear controller drives an external MOSFET
(Q3) to supply the GTL bus power (VOUT3).
the interval between T2 and T3, the error amplifier
reference ramps to the final value and the converter
regulates the output to a voltage proportional to the SS pin
voltage. At T3 the input clamp voltage exceeds the
reference voltage and the output voltage is in regulation.
PGOOD
(2V/DIV)
0V
SOFT-START
(1V/DIV)
0V
VOUT2 ( = 2.5V)
Initialization
The HIP6018B automatically initializes upon receipt of input
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 (+12VIN) at the VCC pin, the 5V input voltage
(+5VIN) on the OCSET1 pin, and the 3.3V input on the VIN2
pin. The normal level on OCSET1 is equal to +5VIN less a
fixed voltage drop (see over-current protection). The POR
function initiates soft-start operation after all three input supply
voltages exceed their POR thresholds.
VOUT1 (DAC = 2V)
OUTPUT
VOLTAGES
(0.5V/DIV)
VOUT3 ( = 1.5V)
0V
T0 T1
T2
T3
T4
TIME
Soft-Start
FIGURE 6. SOFT-START INTERVAL
The POR function initiates the soft-start sequence. Initially,
the voltage on the SS pin rapidly increases to approximately
1V (this minimizes the soft-start interval). Then an internal
11µA current source charges an external capacitor (CSS) on
the SS pin to 4V. The PWM error amplifier reference input
(+terminal) and output (COMP1 pin) is clamped to a level
proportional to the SS pin voltage. As the SS pin voltage
slews from 1V to 4V, the output clamp generates PHASE
pulses of increasing width that charge the output
capacitor(s). After this initial stage, the reference input clamp
slows the output voltage rate-of-rise and provides a smooth
transition to the final set voltage. Additionally both linear
regulator’s reference inputs are clamped to a voltage
proportional to the SS pin voltage. This method provides a
rapid and controlled output voltage rise.
Figure 3 shows the soft-start sequence for the typical
application. At T0 the SS voltage rapidly increases to
approximately 1V. At T1, the SS pin and error amplifier
output voltage reach the valley of the oscillator’s triangle
wave. The oscillator’s triangular waveform is compared to
the clamped error amplifier output voltage. As the SS pin
voltage increases, the pulse-width on the PHASE pin
increases. The interval of increasing pulse-width continues
until each output reaches sufficient voltage to transfer
control to the input reference clamp. If we consider the 2.0V
output (VOUT1) in Figure 3, this time occurs at T2. During
2-244
The remaining outputs are also programmed to follow the SS
pin voltage. Each linear output (VOUT2 and VOUT3) initially
follows a ramp similar to that of the PWM output. When each
output reaches sufficient voltage the input reference clamp
slows the rate of output voltage rise. The PGOOD signal
toggles ‘high’ when all output voltage levels have exceeded
their under-voltage levels. See the Soft-Start Interval section
under Applications Guidelines for a procedure to determine
the soft-start interval.
Fault Protection
All three outputs are monitored and protected against
extreme overload. A sustained overload on any linear
regulator output or an over-voltage on the PWM output
disables all converters and drives the FAULT pin to VCC.
Figure 7 shows a simplified schematic of the fault logic. An
over-voltage detected on VSEN1 immediately sets the fault
latch. A sequence of three over-current fault signals also sets
the fault latch. A comparator indicates when CSS is fully
charged (UP signal), such that an under-voltage event on
either linear output (FB2 or FB3) is ignored until after the softstart interval (T4 in Figure 6). At startup, this allows VOUT2
and VOUT3 to slew up over increased time intervals, without
generating a fault. Cycling the bias input voltage (+12VIN on
the VCC pin) off then on resets the counter and the fault latch.
HIP6018B
pin voltage increases to 4V at T4 and the counter increments to
3. This sets the fault latch to disable the converter. The fault is
reported on the FAULT pin.
LUV
INHIBIT
S
R
0.15V
+
COUNTER
-
R
SS
+
4V
FAULT/RT
S Q
OC1
FAULT
LATCH
S Q
UP
-
POR
R
FAULT
OV
FIGURE 7. FAULT LOGIC - SIMPLIFIED SCHEMATIC
Over-Voltage Protection
During operation, a short on the upper PWM MOSFET (Q1)
causes VOUT1 to increase. When the output exceeds the
over-voltage threshold of 115% (typical) of DACOUT, the
over-voltage comparator trips to set the fault latch and turns
Q2 on as required in order to regulate VOUT1 to 1.15 x
DACOUT. This blows the input fuse and reduces VOUT1.
The fault latch raises the FAULT pin close to VCC potential.
A separate over-voltage circuit provides protection during
the initial application of power. For voltages on the VCC pin
below the power-on reset (and above ~4V), VOUT1 is
monitored for voltages exceeding 1.26V. Should VSEN1
exceed this level, the lower MOSFET (Q2) is driven on as
needed to regulate VOUT1 to 1.26V.
Over-Current Protection
All outputs are protected against excessive over-currents.
The PWM controller uses the upper MOSFET’s onresistance, rDS(ON) to monitor the current for protection
against shorted outputs. The linear regulator monitors the
current of the integrated power device and signals an overcurrent condition for currents in excess of 230mA.
Additionally, both the linear regulator and the linear
controller monitor FB2 and FB3 for under-voltage to protect
against excessive currents.
Figures 8 and 9 illustrate the over-current protection with an
overload on OUT1. The overload is applied at T0 and the
current increases through the output inductor (LOUT1). At time
T1, the OVER-CURRENT1 comparator trips when the voltage
across Q1 (ID • rDS(ON)) exceeds the level programmed by
ROCSET. This inhibits all outputs, discharges the soft-start
capacitor (CSS) with a 11µA current sink, and increments the
counter.CSS recharges at T2 and initiates a soft-start cycle
with the error amplifiers clamped by soft-start. With OUT1 still
overloaded, the inductor current increases to trip the overcurrent comparator. Again, this inhibits all outputs, but the
soft-start voltage continues increasing to 4V before
discharging. The counter increments to 2. The soft-start cycle
repeats at T3 and trips the over-current comparator. The SS
2-245
FAULT
REPORTED
10V
0V
VCC
INDUCTOR CURRENTSOFT-START
OVER
CURRENT
LATCH
COUNT
=1
COUNT
=2
COUNT
=3
4V
2V
0V
OVERLOAD
APPLIED
0A
T0 T1
T2
T3
T4
TIME
FIGURE 8. OVER-CURRENT OPERATION
The linear regulator operates in the same way as PWM1 to
over-current faults. Additionally, the linear regulator and
linear controller monitor the feedback pins for an undervoltage. Should excessive currents cause FB2 or FB3 to fall
below the linear under-voltage threshold, the LUV signal
sets the over-current latch if CSS is fully charged. Blanking the
LUV signal during the CSS charge interval allows the linear
outputs to build above the under-voltage threshold during
normal start-up. Cycling the bias input power off then on
resets the counter and the fault latch.
Resistor ROCSET1 programs the over-current trip level for the
PWM converter. As shown in Figure 9, the internal 200µA
current sink develops a voltage across ROCSET (VSET) that is
referenced to VIN. The DRIVE signal enables the over-current
comparator (OVER-CURRENT1). When the voltage across the
upper MOSFET (VDS(ON)) exceeds VSET, the over-current
comparator trips to set the over-current latch. Both VSET and
VDS are referenced to VIN and a small capacitor across
ROCSET helps VOCSET track the variations of VIN due to
MOSFET switching. The over-current function will trip at a peak
inductor current (IPEAK) determined by:
I OCSET xR OCSET
I PEAK = ------------------------------------------------------r DS ( ON )
HIP6018B
OVER-CURRENT TRIP: VDS > VSET
TABLE 1. VOUT1 VOLTAGE PROGRAM
VIN = +5V
(iD • rDS(ON) > IOCSET • ROCSET)
PIN NAME
VID4
VID3
VID2
VID1
VID0
NOMINAL
OUT1
VOLTAGE
DACOUT
0
1
1
1
1
1.30
0
1
1
1
0
1.35
0
1
1
0
1
1.40
0
1
1
0
0
1.45
0
1
0
1
1
1.50
0
1
0
1
0
1.55
0
1
0
0
1
1.60
0
1
0
0
0
1.65
0
0
1
1
1
1.70
0
0
1
1
0
1.75
0
0
1
0
1
1.80
1. The maximum rDS(ON) at the highest junction temperature.
0
0
1
0
0
1.85
2. The minimum IOCSET from the specification table.
0
0
0
1
1
1.90
3. Determine IPEAK for IPEAK > IOUT(MAX) + (∆I)/2,
where ∆I is the output inductor ripple current.
0
0
0
1
0
1.95
0
0
0
0
1
2.00
0
0
0
0
0
2.05
1
1
1
1
1
INHIBIT
OUT1 Voltage Program
1
1
1
1
0
2.1
The output voltage of the PWM converter is programmed to
discrete levels between 1.3VDC and 3.5VDC . This output is
designed to supply the microprocessor core voltage. The
voltage identification (VID) pins program an internal voltage
reference (DACOUT) through a TTL-compatible 5-bit
digital-to-analog converter. The level of DACOUT also sets
the PGOOD and OVP thresholds. Table 1 specifies the
DACOUT voltage for the different combinations of
connections on the VID pins. The VID pins can be left open
for a logic 1 input, because they are internally pulled up to
+5V by a 10µA (typically) current source. Changing the VID
inputs during operation is not recommended. The sudden
change in the resulting reference voltage could toggle the
PGOOD signal and exercise the over-voltage protection.
1
1
1
0
1
2.2
1
1
1
0
0
2.3
1
1
0
1
1
2.4
1
1
0
1
0
2.5
1
1
0
0
1
2.6
1
1
0
0
0
2.7
1
0
1
1
1
2.8
1
0
1
1
0
2.9
1
0
1
0
1
3.0
1
0
1
0
0
3.1
1
0
0
1
1
3.2
The ‘11111’ VID pin combination resulting in an INHIBIT
disables the IC and the open-collector at the PGOOD pin.
1
0
0
1
0
3.3
1
0
0
0
1
3.4
1
0
0
0
0
3.5
OCSET
IOCSET
200µA
ROCSET
VSET +
ID
VCC
+
UGATE
DRIVE
OC1
+
PHASE
-
OVERCURRENT1
PWM
VDS
VCC
LGATE
GATE
CONTROL
VPHASE = VIN - VDS
VOCSET = VIN - VSET
PGND
HIP6018B
FIGURE 9. OVER-CURRENT DETECTION
The OC trip point varies with MOSFET’s temperature. To avoid
over-current tripping in the normal operating load range,
determine the ROCSET resistor from the equation above with:
For an equation for the output inductor ripple current see the
section under component guidelines titled ‘Output Inductor
Selection’.
NOTE: 0 = connected to GND or VSS, 1 = open or connected to 5V
through pull-up resistors.
2-246
HIP6018B
Initially, the soft-start function clamps the error amplifier’s output
of the PWM converter. After the output voltage increases to
approximately 80% of the set value, the reference input of the
error amplifier is clamped to a voltage proportional to the SS pin
voltage. Both linear outputs follow a similar start-up sequence.
The resulting output voltage sequence is shown in Figure 6.
The soft-start function controls the output voltage rate of rise
to limit the current surge at start-up. The soft-start interval is
programmed by the soft-start capacitor, CSS. Programming
a faster soft-start interval increases the peak surge current.
The peak surge current occurs during the initial output
voltage rise to 80% of the set value.
+5VIN
+3.3VIN
CIN
+12V
CVCC
COCSET1
VCC GND
VIN2 OCSET1
VOUT3
Q3
GATE3UGATE1
ROCSET1
Q1
LOUT1
VOUT1
PHASE1
HIP6018B
VOUT2 LGATE1
Q2
COUT1
CR1
LOAD
Soft-Start Interval
The critical small signal components include the by-pass
capacitor for VCC and the soft-start capacitor, CSS. Locate
these components close to their connecting pins on the
control IC. Minimize any leakage current paths from SS node
because the internal current source is only 11µA.
LOAD
Application Guidelines
SS PGND
Shutdown
The VID codes resulting in an INHIBIT as shown in Table 1
also shuts down the IC.
Layout Considerations
MOSFETs switch very fast and efficiently. The speed with which
the current transitions from one device to another causes voltage
spikes across the interconnecting impedances and parasitic
circuit elements. The voltage spikes can degrade efficiency,
radiate noise into the circuit, and lead to device over-voltage
stress. Careful component layout and printed circuit design
minimizes the voltage spikes in the converter. Consider, as an
example, the turn-off transition of the upper PWM MOSFET.
Prior to turn-off, the upper MOSFET was carrying the full load
current. During the turn-off, current stops flowing in the upper
MOSFET and is picked up by the lower MOSFET (and/or parallel
Schottky diode). Any inductance in the switched current path
generates a large voltage spike during the switching interval.
Careful component selection, tight layout of the critical
components, and short, wide circuit traces minimize the
magnitude of voltage spikes. Contact Intersil for evaluation board
drawings of the component placement and printed circuit board.
There are two sets of critical components in a DC-DC converter
using a HIP6018B controller. The power components are the
most critical because they switch large amounts of energy. The
critical small signal components connect to sensitive nodes or
supply critical by-passing current.
The power components should be placed first. Locate the
input capacitors close to the power switches. Minimize the
length of the connections between the input capacitors and
the power switches. Locate the output inductor and output
capacitors between the MOSFETs and the load. Locate the
PWM controller close to the MOSFETs.
2-247
CSS
VOUT2
LOAD
The PWM output does not switch until the soft-start voltage
(VSS) exceeds the oscillator’s valley voltage. Additionally, the
reference on each linear’s amplifier is clamped to the softstart voltage. Holding the SS pin low with an open drain or
collector signal turns off all three regulators.
COUT2
KEY
ISLAND ON POWER PLANE LAYER
ISLAND ON CIRCUIT PLANE LAYER
VIA CONNECTION TO GROUND PLANE
FIGURE 10. PRINTED CIRCUIT BOARD POWER PLANES AND
ISLANDS
A multi-layer printed circuit board is recommended. Figure 10
shows the connections of the critical components in the
converter. Note that capacitors CIN and COUT could each
represent numerous physical capacitors. Dedicate one solid
layer for a ground plane and make all critical component
ground connections with vias to this layer. Dedicate another
solid layer as a power plane and break this plane into
smaller islands of common voltage levels. The power plane
should support the input power and output power nodes.
Use copper filled polygons on the top and bottom circuit
layers for the phase nodes. Use the remaining printed circuit
layers for small signal wiring. The wiring traces from the
control IC to the MOSFET gate and source should be sized
to carry 1A currents. The traces for OUT2 need only be sized
for 0.2A. Locate COUT2 close to the HIP6018B IC.
PWM Controller Feedback Compensation
Both PWM controllers use voltage-mode control for output
regulation. This section highlights the design consideration
for a voltage-mode controller. Apply the methods and
considerations to both PWM controllers.
Figure 11 highlights the voltage-mode control loop for a
synchronous-rectified buck converter. The output voltage is
regulated to the reference voltage level. The reference voltage
level is the DAC output voltage for the PWM controller. The
error amplifier output (VE/A) is compared with the oscillator
(OSC) triangular wave to provide a pulse-width modulated
wave with an amplitude of VIN at the PHASE node. The PWM
wave is smoothed by the output filter (LO and CO).
HIP6018B
Compensation Break Frequency Equations
VIN
OSC
∆ VOSC
DRIVER
PWM
COMP
LO
-
DRIVER
+
VOUT
PHASE
CO
ESR
(PARASITIC)
ZFB
VE/A
ZIN
ERROR
AMP
+
REFERENCE
DETAILED FEEDBACK COMPENSATION
ZFB
VOUT
C2
C1
1
F P1 = ------------------------------------------------------C1 × C2
2π × R 2 ×  ----------------------
 C1 + C2
1
F Z1 = ----------------------------------2π × R 2 × C1
ZIN
C3
R2
R3
R1
1
F P2 = ----------------------------------2π × R 3 × C3
1
F Z2 = ------------------------------------------------------2π × ( R1 + R3 ) × C3
Figure 12 shows an asymptotic plot of the DC-DC converter’s
gain vs. frequency. The actual modulator gain has a peak due
to the high Q factor of the output filter at FLC, which is not
shown in Figure 12. Using the above guidelines should yield a
compensation gain similar to the curve plotted. The open loop
error amplifier gain bounds the compensation gain. Check the
compensation gain at FP2 with the capabilities of the error
amplifier. The closed loop gain is constructed on the log-log
graph of Figure 12 by adding the modulator gain (in dB) to the
compensation gain (in dB). This is equivalent to multiplying
the modulator transfer function to the compensation transfer
function and plotting the gain.
COMP
+
FB
100
FZ1 FZ2
FP1
FP2
80
HIP6018B
REFERENCE
The modulator transfer function is the small-signal transfer
function of VOUT/VE/A. This function is dominated by a DC
gain and the output filter, with a double pole break frequency
at FLC and a zero at FESR. The DC gain of the modulator is
simply the input voltage, VIN, divided by the peak-to-peak
oscillator voltage, ∆VOSC .
Modulator Break Frequency Equations
1
F LC = ---------------------------------------2π × L O × C O
1
F ESR = ----------------------------------------2π × ESR × C O
The compensation network consists of the error amplifier
internal to the HIP6018B and the impedance networks ZIN and
ZFB. The goal of the compensation network is to provide a
closed loop transfer function with an acceptable 0dB crossing
frequency (f0dB) and adequate phase margin. Phase margin is
the difference between the closed loop phase at f0dB and 180
degrees. The equations below relate the compensation
network’s poles, zeros and gain to the components (R1, R2,
R3, C1, C2, and C3) in Figure 11. Use these guidelines for
locating the poles and zeros of the compensation network:
1. Pick Gain (R2/R1) for desired converter bandwidth
2. Place 1ST Zero Below Filter’s Double Pole (~75% FLC)
3. Place 2ND Zero at Filter’s Double Pole
4. Place 1ST Pole at the ESR Zero
5. Place 2ND Pole at Half the Switching Frequency
6. Check Gain against Error Amplifier’s Open-Loop Gain
7. Estimate Phase Margin - Repeat if Necessary
2-248
GAIN (dB)
FIGURE 11. VOLTAGE-MODE BUCK CONVERTER
COMPENSATION DESIGN
OPEN LOOP
ERROR AMP GAIN
60
40
20
20LOG
(R2/R1)
0
20LOG
(VIN/∆VOSC)
MODULATOR
GAIN
-20
COMPENSATION
GAIN
CLOSED LOOP
GAIN
-40
FLC
-60
10
100
1K
FESR
10K
100K
1M
10M
FREQUENCY (Hz)
FIGURE 12. ASYMPTOTIC BODE PLOT OF CONVERTER GAIN
The compensation gain uses external impedance networks
ZFB and ZIN to provide a stable, high bandwidth loop. A
stable control loop has a 0dB gain crossing with
-20dB/decade slope and a phase margin greater than 45
degrees. Include worst case component variations when
determining phase margin.
Component Selection Guidelines
Output Capacitor Selection
The output capacitors for each output have unique
requirements. In general the output capacitors should be
selected to meet the dynamic regulation requirements.
Additionally, the PWM converters require an output capacitor
to filter the current ripple. The linear regulator is internally
compensated and requires an output capacitor that meets
the stability requirements. The load transient for the
microprocessor core requires high quality capacitors to
supply the high slew rate (di/dt) current demands.
HIP6018B
PWM Output Capacitors
Modern microprocessors produce transient load rates above
10A/ns. High frequency capacitors initially supply the transient
and slow the current load rate seen by the bulk capacitors.
The bulk filter capacitor values are generally determined by
the ESR (effective series resistance) and ESL (effective series
inductance) parameters rather than actual capacitance.
High frequency decoupling capacitors should be placed as
close to the power pins of the load as physically possible. Be
careful not to add inductance in the circuit board wiring that
could cancel the usefulness of these low inductance
components. Consult with the manufacturer of the load on
specific decoupling requirements.
Use only specialized low-ESR capacitors intended for switching
regulator applications for the bulk capacitors. The bulk
capacitor’s ESR determines the output ripple voltage and the
initial voltage drop after a high slew-rate transient. An aluminum
electrolytic capacitor’s ESR value is related to the case size
with lower ESR available in larger case sizes. However, the
equivalent series inductance of these capacitors increases with
case size and can reduce the usefulness of the capacitor to
high slew-rate transient loading. Unfortunately, ESL is not a
specified parameter. Work with your capacitor supplier and
measure the capacitor’s impedance with frequency to select
suitable components. In most cases, multiple electrolytic
capacitors of small case size perform better than a single large
case capacitor. For a given transient load magnitude, the output
voltage transient response due to the output capacitor
characteristics can be approximated by the following equation:
dI TRAN
V TRAN = ESL × --------------------- + ESR × I TRAN
dt
Linear Output Capacitors
The output capacitors for the linear regulator and the linear
controller provide dynamic load current. The linear controller
uses dominant pole compensation integrated in the error
amplifier and is insensitive to output capacitor selection.
Capacitor, COUT3 should be selected for transient load
regulation.
The output capacitor for the linear regulator provides loop
stability. The linear regulator (OUT2) requires an output
capacitor characteristic shown in Figure 13. The upper line
plots the 45 phase margin with 150mA load and the lower
line is the 45 phase margin limit with a 10mA load. Select a
COUT2 capacitor with characteristic between the two limits.
Output Inductor Selection
The PWM converter requires an output inductor. The output
inductor is selected to meet the output voltage ripple
requirements and sets the converter’s response time to a
load transient. The inductor value determines the converter’s
ripple current and the ripple voltage is a function of the ripple
current. The ripple voltage and current are approximated by
the following equations:
2-249
0.7
0.6
0.5
ESR (Ω)
0.4
LE
AB TION
T
S
A
ER
OP
0.3
0.2
0.1
10
100
CAPACITANCE (µF)
1000
FIGURE 13. COUT2 OUTPUT CAPACITOR
V IN – V OUT V OUT
∆I = -------------------------------- × ---------------V IN
FS × LO
∆V OUT = ∆I × ESR
Increasing the value of inductance reduces the ripple current
and voltage. However, the large inductance values reduce
the converter’s response time to a load transient.
One of the parameters limiting the converter’s response to a
load transient is the time required to change the inductor
current. Given a sufficiently fast control loop design, the
HIP6018B will provide either 0% or 100% duty cycle in
response to a load transient. The response time is the time
interval required to slew the inductor current from an initial
current value to the post-transient current level. During this
interval the difference between the inductor current and the
transient current level must be supplied by the output
capacitors. Minimizing the response time can minimize the
output capacitance required.
The response time to a transient is different for the
application of load and the removal of load. The following
equations give the approximate response time interval for
application and removal of a transient load:
L O × I TRAN
t RISE = -------------------------------V IN – V OUT
L O × I TRAN
t FALL = ------------------------------V OUT
where: ITRAN is the transient load current step, tRISE is the
response time to the application of load, and tFALL is the
response time to the removal of load. With a +5V input
source, the worst case response time can be either at the
application or removal of load, and dependent upon the
output voltage setting. Be sure to check both of these
equations at the minimum and maximum output levels for the
worst case response time.
Input Capacitor Selection
The important parameters for the bulk input capacitor are the
voltage rating and the RMS current rating. For reliable
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.
HIP6018B
Use a mix of input bypass capacitors to control the voltage
overshoot across the MOSFETs. Use ceramic capacitance
for the high frequency decoupling and bulk capacitors to
supply the RMS current. Small ceramic capacitors should be
placed very close to the upper MOSFET to suppress the
voltage induced in the parasitic circuit impedances.
For a through hole design, several electrolytic capacitors
(Panasonic HFQ series or Nichicon PL series or Sanyo MVGX 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 surgecurrent at power-up. The TPS series available from AVX, and
the 593D series from Sprague are both surge current tested.
MOSFET Selection/Considerations
The HIP6018B requires 3 N-Channel power MOSFETs. Two
MOSFETs are used in the synchronous-rectified buck
topology of the PWM converter. The linear controller drives a
MOSFET as a pass transistor. These should be selected
based upon rDS(ON) , gate supply requirements, and thermal
management requirements.
PWM1 MOSFET Selection and Considerations
In high-current PWM 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. These losses
are distributed between the upper and lower MOSFETs
according to duty factor (see the equations below). The
conduction loss is the only component of power dissipation for
the lower MOSFET. Only the upper MOSFET has switching
losses, since the lower device turns on into near zero voltage.
The equations below assume linear voltage-current transitions
and do not model power loss due to the reverse-recovery of the
lower MOSFET’s body diode. The gate-charge losses are
proportional to the switching frequency (FS) and are dissipated
by the HIP6018B, thus not contributing to the MOSFETs’
temperature rise. However, large gate charge increases the
switching interval, tSW which increases the upper MOSFET
switching losses. Ensure that both MOSFETs are within their
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.
2
I O × r DS ( ON ) × V OUT I O × V IN × t SW × F S
P UPPER = ------------------------------------------------------------ + ---------------------------------------------------V IN
2
MOSFET. Figure 14 shows the gate drive where the upper gateto-source voltage is approximately VCC less the input supply. For
+5V main power and +12VDC for the bias, the gate-to-source
voltage of Q1 is 7V. The lower gate drive voltage is +12VDC. A
logic-level MOSFET is a good choice for Q1 and a logic-level
MOSFET can be used for Q2 if its absolute gate-to-source
voltage rating exceeds the maximum voltage applied to VCC.
+5V OR LESS
+12V
VCC
HIP6018B
UGATE
PHASE
-
+
LGATE
The rDS(ON) is different for the two previous equations even if the
type device is used for both. This is because the gate drive
applied to the upper MOSFET is different than the lower
2-250
NOTE:
VGS ≈ VCC -5V
Q2
CR1
PGND
NOTE:
VGS ≈ VCC
GND
FIGURE 14. OUTPUT GATE DRIVERS
Rectifier CR1 is a clamp that catches the negative inductor
voltage swing during the dead time between the turn off of the
lower MOSFET and the turn on of the upper MOSFET. The
diode must be a Schottky type to prevent the lossy parasitic
MOSFET body diode from conducting. It is acceptable to omit
the diode and let the body diode of the lower MOSFET clamp
the negative inductor swing, but efficiency might drop one or
two percent as a result. The diode's rated reverse breakdown
voltage must be greater than twice the maximum input voltage.
Linear Controller MOSFET Selection
The main criteria for the selection of a transistor for the linear
regulator is package selection for efficient removal of heat.
The power dissipated in a linear regulator is:
P LINEAR = I O × ( V IN – V OUT )
Select a package and heatsink that maintains the junction
temperature below the maximum rating while operating at
the highest expected ambient temperature.
Additionally, if selecting a bipolar NPN transistor, insure the gain
(hfe) at the minimum operating temperature and given collectorto-emitter voltage is sufficiently high as to deliver the worst-case
steady state current required by the GTL output, when the
transistor is driven with the minimum guaranteed DRIVE3
output current. For example, operating at “T” junction
temperature, 3.3V input, and 1.5V output (VCE = 1.8V) the
NPN’s gain should satisfy the following equation:
2
I O × r DS ( ON ) × ( V IN – V OUT )
P LOWER = --------------------------------------------------------------------------------V IN
Q1
I GTL ( steady – state )
h fe > ----------------------------------------------------------I DRIVE3 ( min )
HIP6018B
HIP6018B DC-DC Converter Application Circuit
the circuit, including a Bill-of-Materials and circuit board
description, see Application Note AN9805. Also see Intersil’s
web page (http://www.intersil.com) or Intersil AnswerFAX
(407-724-7800) document # 99805 for the latest information.
Figure 15 shows an application circuit of a power supply for
a microprocessor computer system. The power supply provides the microprocessor core voltage (VOUT1), the GTL bus
voltage (VOUT3) and clock generator voltage (VOUT2) from
+3.3VDC, +5VDC and +12VDC. For detailed information on
+12VIN
L1
F1
+5VIN
15A
1µH
C1-7
6x1000µF
GND
+
C15
1µF
C16
1µF
C18
VCC
1000pF
R2
1
VIN2
+3.3VIN
20
OCSET1 1.1K
12
POWERGOOD
+
7
C19
1000µF
24
23
PGOOD
Q1
HUF76143
UGATE1
PHASE1
VOUT1
(1.3 TO 3.5V)
L3
3.5µH
Q3
RFD3055
DRIVE3
VOUT3
R11
(1.5V)
1.87K
+
C43-46
4x1000µF
R13
(2.5V)
10K
C47
270µF
15
21
16
LGATE1
PGND
R4
4.99K
VSEN1
HIP6018B
FB2
18
13
11
17
R8
C40
2.21K
0.68µF
FB1
COMP1
R14
10K
C41
10pF
C42
R10
2200pF 160K
VID0
VID0
VID1
VID1
VID2
VID2
VID3
VID3
VID4
VID4
C24-36 +
7x1000µF
Q2
HUF76143
19
R12
10K
VOUT2
VOUT2
+
FB3
22
8
6
5
10
4
9
732K
FAULT
RT
SS
3
2
R9
C48
0.039µF
14
GND
FIGURE 15. APPLICATION CIRCUIT
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Intersil semiconductor products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
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