intersil HIP6004B DATA SHEET

®
HIP6004B
Data Sheet October 2003 FN4567.3
Buck and Synchronous-Rectifier (PWM) Controller and Output Voltage Monitor
The HIP6004B provides complete control and protection for a DC-DC converter optimized for high-performance microprocessor applications. It is designed to drive two N-Channel MOSFETs in a synchronous-rectified buck topology. The HIP6004B integrates all of the control, output adjustment, monitoring and protection functions into a single package.
The output voltage of the converter is easily adjusted and precisely regulated. The HIP6004B includes a fully TTL-compatible 5-input digital-to-analog converter (DAC) that adjusts the output voltage from 1.3V
0.05V and from 2.1V
to 3.5VDC in 0.1V increments steps.
DC
to 2.05VDC in
DC
The precision reference and voltage-mode regulator hold the selected output voltage to within ±1% over temperature and line voltage variations.
The HIP6004B provides simple, single feedback loop, voltage-mode control with fast transient response. It includes a 200kHz free-running triangle-wave oscillator that is adjustable from below 50kHz to over 1MHz. The error amplifier features a 15MHz gain-bandwidth product and 6V/µs slew rate which enables high converter bandwidth for fast transient performance. The resulting PWM duty ratio ranges from 0% to 100%.
The HIP6004B monitors the output voltage with a window comparator that tracks the DAC output and issues a Power Good signal when the output is within ±10%. The HIP6004B protects against over-current and overvoltage conditions by inhibiting PWM operation. Addi t io n al bu i lt - i n overvoltage protection triggers an external SCR to crowbar the input supply. The HIP6004B monitors the current by using the r
of the upper MOSFET which eliminates the need for
DS(ON)
a current sensing resistor.
Ordering Information
PART NUMBER
HIP6004BCB 0 to 70 20 Ld SOIC M20.3 HIP6004BCV 0 to 70 20 Ld TSSOP M20.173 HIP6004BCR 0 to 70 20 Ld 5x5 QFN L20.5x5
TEMP.
RANGE (oC) PACKAGE
PKG.
DWG. #
Features
• Drives Two N-Channel MOSFETs
• Operates from +5V or +12V Input
• Simple Single-Loop Control Design
- Voltage-Mode PWM Control
• Fast Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Ratio
• Excellent Output Voltage Regulation
- ±1% Over Line Voltage and Temperature
• TTL-Compatible 5-Bit Digital-to-Analog Output Voltage Selection
- Wide Range . . . . . . . . . . . . . . . . . . . 1.3V
DC
to 3.5V
- 0.1V Binary Steps . . . . . . . . . . . . . . 2.1VDC to 3.5V
- 0.05V Binary Steps . . . . . . . . . . . . 1.3VDC to 2.05V
• Power-Good Output Voltage Monitor
• Over-Voltage and Over-Current Fault Monitors
- Does Not Require Extra Current Sensing Element,
Uses MOSFET’s r
DS(ON)
• Small Converter Size
- Constant Frequency Operation
- 200kHz Free-Running Oscillator Programmable from
50kHz to over 1MHz
• QFN Package:
- Compliant to JEDEC PUB95 MO-220
QFN - Quad Flat No Leads - Package Outline
- Near Chip Scale Package footprint, which improves
PCB efficiency and has a thinner profile
Applications
• Power Supply for Pentium®, Pentium Pro, Pentium II, PowerPC™, K6™, 6X86™ and Alpha™ Microprocessors
High-Power 5V to 3.xV DC-DC Regulators
Low-Voltage Distributed Power Supplies
DC DC DC
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
| Intersil (and design) is a registered trademark of Intersil Americas Inc.
All other trademarks mentioned are the property of their respective owners.
Copyright © Intersil Americas Inc. 2003. All Rights Reserved.
Pinouts
HIP6004B (SOIC, TSSOP)
TOP VIEW
HIP6004B
HIP6004B (QFN)
TOP VIEW
1
V
SEN
OCSET
SS VID0 VID1 VID2 VID3 VID4
COMP
FB
2 3 4 5 6 7 8 9
10
Typical Application
PGOOD
SS
OVP
RT
20
OVP
19
V
18
CC
LGATE
17
PGND
16
BOOT
15
UGATE
14
PHASE
13 12
PGOOD GND
11
+12V
MONITOR AND
PROTECTION
VCC
OCSET EN BOOT
SS
20 19 18 17 16
VID0
1
VID1
2
VID2
3
VID3
4
VID4
5
678910
COMP
VIN = +5V OR +12V
OCSET
FB
GND
21
VSEN
GND
RT
PGOOD
OVP
VCC
15
LGATE
14
PGND
13
BOOT
12
UGATE
11
PHASE
VID0 VID1 VID2 VID3 VID4
RT
FB
D/A
OSC
+
-
COMP
HIP6004B
+
-
VSEN
GND
UGATE PHASE
LGATE PGND
+V
OUT
2
Block Diagram
V
SEN
OCSET
VID0 VID1 VID2 VID3 VID4
FB
COMP
RT
REFERENCE
TTL D/A
CONVERTER
(DAC)
200µA
DACOUT
110%
90%
115%
HIP6004B
+
-
+
­OVER-
VOLTAGE
+
-
+
-
OVER-
CURRENT
+
-
ERROR
AMP
OSCILLATOR
RESET (POR)
4V
PWM
COMPARATOR
+
-
V
CC
POWER-ON
SOFT-
START
INHIBIT
PWM
PGOOD
10µA
OVP
SS
BOOT UGATE
PHASE
GATE
CONTROL
LOGIC
LGATE PGND GND
3
4
HIP6004B
Electrical Specifications Recommended Operating Conditions, Unless Otherwise Noted (Continued)
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNITS
POWER GOOD
Upper Threshold (V Lower Threshold (V Hysteresis (V
SEN
/DACOUT) V
SEN
/DACOUT) V
SEN
/DACOUT) Upper and Lower Threshold - 2 - %
PGOOD Voltage Low V
PGOODIPGOOD
Rising 106 - 111 %
SEN
Falling 89 - 94 %
SEN
= -5mA - 0.5 - V
Typical Performance Curves
80
70
1000
RT PULLUP
TO +12V
60
C
= C
UPPER
50
LOWER
= C
GATE
C
GATE
= 3300pF
100
RESISTANCE (kΩ)
10
10 100 1000
SWITCHING FREQUENCY (kHz)
RT PULLDOWN TO V
SS
FIGURE 1. RT RESISTANCE vs FREQUENCY FIGURE 2. BIAS SUPPLY CURRENT vs FREQUENCY
Functional Pin Descriptions
1
V
SEN
V
SEN
OCSET
(Pin 1)
SS VID0 VID1 VID2 VID3 VID4
COMP
FB
2 3 4 5 6 7 8 9
10
This pin is connected to the converters output voltage. The PGOOD and OVP comparator circuits use this signal to report output voltage status and for overvoltage protection.
OCSET (Pin 2)
Connect a resistor (R upper MOSFET. R (I
), and the upper MOSFET on-resistance (r
OCS
OCSET
) from this pin to the drain of the
OCSET
, an internal 200µA current source
20 19 18 17 16 15 14 13 12 11
RT OVP VCC LGATE PGND BOOT UGATE PHASE PGOOD GND
DS(ON)
) set
40
(mA)
CC
I
30
20
10
0
100 200 300 400 500 600 700 800 900 1000
SWITCHING FREQUENCY (kHz)
C
C
GATE
GATE
= 1000pF
= 10pF
the converter over-current (OC) trip point according to the following equation:
I
PEAK
OCSET
-----------------------------------------------------
=
OCSET
r
DS ON()
I
x R
An over-current trip cycles the soft-start function.
SS (Pin 3)
Connect a capacitor from this pin to ground. This capacitor, along with an internal 10µA current source, sets the soft­start interval of the converter.
VID0-4 (Pins 4-8)
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 converter output voltage. It also sets the PGOOD and OVP thresholds. Table 1 specifies DACOUT for the all combinations of DAC inputs.
COMP (Pin 9) and FB (Pin 10)
COMP and FB are the available external pins of the error amplifier. The FB pin is the inverting input of the error amplifier and the COMP pin is the error amplifier output. These pins are used to compensate the voltage-control feedback loop of the converter.
5
GND (Pin 11)
Signal ground for the IC. All voltage levels are measured with respect to this pin.
PGOOD (Pin 12)
PGOOD is an open collector output used to indicate the status of the converter output voltage. This pin is pulled low when the converter output is not within
±10% of the
DACOUT reference voltage. Exception to this behavior is the ‘11111’ VID pin combination which disables the converter; in this case PGOOD asserts a high level.
PHASE (Pin 13)
Connect the PHASE pin to the upper MOSFET source. This pin is used to monitor the voltage drop across the MOSFET for over-current protection. This pin also provides the return path for the upper gate drive.
UGATE (Pin 14)
Connect UGATE to the upper MOSFET gate. This pin provides the gate drive for the upper MOSFET.
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.
PGND (Pin 16)
This is the power ground connection. Tie the lower MOSFET source to this pin.
LGATE (Pin 17)
Connect LGATE to the lower MOSFET gate. This pin provides the gate drive for the lower MOSFET.
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. Output rising 15% more than the DAC-set voltage triggers a high output on this pin and disables PWM gate drive circuitry.
Functional Description
Initialization
The HIP6004B 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 V pin and the input voltage (V OCSET is equal to V
IN
) on the OCSET pin. The level on
IN
less a fixed voltage drop (see over­current 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 and V exceed the rising V
are equivalent and the +12V power source must
CC
threshold before POR initiates operation.
CC
Soft Start
The POR function initiates the soft start sequence. An internal 10µA current source charges an external capacitor (C the SS pin to 4V. Soft start clamps the error 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
= 0.1µF . Initially the clam p on the error a mplifier (CO MP
SS
pin) controls the converter’s output voltage. At t 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 t output voltage, the clamp on the ref erence input control s the output voltage. This is the interval between t At t
the SS voltage exceeds the DACOUT voltage and the
3
output voltage is in regulation. This method provides a rapid and controlled output voltage rise. The PGOOD signal toggles ‘high’ when the output voltage (V
pin) is within ±5% of
SEN
DACOUT. The 2% hysteresis built into the power good comparators prevents PGOOD oscillation due to nominal output voltage ripple.
in Figure 3,
1
. With sufficient
2
and t3 in Figure 3.
2
SS
CC
IN
) on
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:
5 x 10
Fs 200kHz
---------------------
+
RTk()
Conversely, connecting a pull-up resistor (R to V
reduces the switching frequency according to the
CC
following equation:
4 x 10
Fs 200kHz
---------------------
RTk()
) from this pin to GND, the nominal
T
6
(RT to GND)
) from this pin
T
7
(RT to 12V)
6
HIP6004B
Over-Current Protection
The over-current function protects the converter from a shorted output by using the upper MOSFET’s on-resistance, r converter’s efficiency and reduces cost by eliminating a current sensing resistor.
The over-current function cycles the soft-start function in a hiccup mode to provide fault protection. A resistor (R programs the over-current trip level. An internal 200µA current sink develops a voltage across R V referenced to V over-current function initiates a soft-start sequence. The soft­start function discharges C inhibits PWM operation. The soft-start function recharges C clamped to the SS voltage. Should an overload occur while recharging C while fully charging C shows this operation with an overload condition. Note that the inductor current increases to over 15A during the C charging interval and causes an over-current trip. The converter dissipates very little power with this method. The measured input power for the conditions of Figure 4 is 2.5W.
The over-current function will trip at a peak inductor current (I
I
to monitor the current. This method enhances the
DS(ON)
4V
2V
0V
15A
10A
5A
OUTPUT INDUCTOR SOFT-START
0A
TIME (20ms/DIV)
FIGURE 4. OVER-CURRENT OPERATION
that is referenced to
. When the voltage across the upper MOSFET (also
IN
, and PWM operation resumes with the error amplifier
SS
determined by:
PEAK)
I
-----------------------------------------------------
=
PEAK
) exceeds the voltage across R
IN
, the soft start function inhibits PWM operation
SS
OCSET
r
DS ON()
to 4V to complete its cycle. Figure 4
SS
x R
OCSET
OCSET
OCSET
with a 10µA current sink and
SS
OCSET
SS
)
, the
where I
is the internal OCSET current source (200µA
OCSET
typical). The OC trip point varies mainly due to the MOSFET’s r tripping in the normal operating load range, find the R
variations. To avoid over-current
DS(ON)
OCSET
resistor from the equation above with:
1. The maximum r
at the highest junction
DS(ON)
temperature.
2. The minimum I
3. Determine I
PEAK
where I is the output inductor ripple current.
from the specification table.
OCSET
for
I
PEAKIOUT MAX()
,
I()2+>
For an equation for the ripple current see the section under component guidelines titled ‘Output Inductor Selection’.
A small ceramic capacitor should be placed in parallel with R
to smooth the voltage across R
OCSET
OCSET
in the
presence of switching noise on the input voltage.
Output Voltage Program
The output voltage of a HIP6004B converter is programmed to discrete levels between 1.8V
and 3.5VDC. The voltage
DC
identification (VID) pins program an internal voltage reference (DACOUT) with a TTL-compatible 5-bit digital-to-analog converter (DAC). The level of DACOUT also sets the PGOOD and OVP thresholds. Table 1 specifies the DACOUT voltage for the 32 different combinations of connections on the VID pins. The output voltage should not be adjusted while the converter is delivering power. Remove input power before changing the output voltage. Adjusting the output voltage during operation could toggle the PGOOD signal and exercise the overvoltage protection.
‘11111’ VID pin combination resulting in a 0V output setting activates the Power-On Reset function and disables the gate drives circuitry. For this specific VID combination, though, PGOOD asserts a high level. This unusual behavior has been implemented in order to allow for operation in dual­microprocessor systems where AND-ing of the PGOOD signals from two individual power converters is implemented.
Application Guidelines
Layout Considerations
As in any high frequency switching converter, layout is very important. Switching current from one power device to another can generate voltage transients across the impedances of the interconnecting bond wires and circuit traces. These interconnecting impedances should be minimized by using wide, short printed circuit traces. The critical components should be located as close together as possible, using ground plane construction or single point grounding.
7
HIP6004B
TABLE 1. OUTPUT VOLTAGE PROGRAM
PIN NAME
NOMINAL OUTPUT
VOLTAGE DACOUT
01111 1.30 11111 0 01110 1.35 11110 2.1 01101 1.40 11101 2.2 01100 1.45 11100 2.3 01011 1.50 11011 2.4 01010 1.55 11010 2.5 01001 1.60 11001 2.6 01000 1.65 11000 2.7 00111 1.70 10111 2.8 00110 1.75 10110 2.9 00101 1.80 10101 3.0 00100 1.85 10100 3.1 00011 1.90 10011 3.2 00010 1.95 10010 3.3 00001 2.00 10001 3.4 00000 2.05 10000 3.5
NOTE: 0 = connected to GND or V
, 1 = connected to VDD through pull-up resistors.
SS
PIN NAME
NOMINAL OUTPUT
VOLTAGE DACOUTVID4 VID3 VID2 VID1 VID0 VID4 VID3 VID2 VID1 VID0
V
IN
HIP6004B
UGATE PHASE
LGATE
PGND
Q
1
Q
2
RETURN
L
O
V
OUT
C
IN
C
D
2
O
LOAD
FIGURE 5. PRINTED CIRCUIT BOARD POWER AND
GROUND PLANES OR ISLANDS
Figure 5 shows the critical power components of the converter. To minimize the voltage overshoot the interconnecting wires indicated by heavy lines should be part of ground or power plane in a printed circuit board. The components shown in Figure 5 should be located as close together as possible. Please note that the capacitors C
and CO each represent
IN
numerous physical capacitors. Locate the HIP6004B within 3 inches of the MOSFETs, Q
and Q2. The circuit traces for the
1
MOSFETs’ gate and source connections from the HIP6004B must be sized to handle up to 1A peak current.
Figure 6 shows the circuit traces that require additional layout consideration. Use single point and ground plane construction for the circuits shown. Minimize any leakage
current paths on the SS PIN and locate the capacitor, C
SS
close to the SS pin because the internal current source is only 10µA. Provide local V GND pins. Locate the capacitor, C
decoupling between VCC and
CC
BOOT
as close as
practical to the BOOT and PHASE pins.
+V
IN
Q
L
1
O
C
Q
2
V
OUT
O
SS
C
SS
HIP6004B
GND
BOOT
C
BOOT
PHASE V
CC
+12V
C
D
VCC
1
FIGURE 6. PRINTED CIRCUIT BOARD SMALL SIGNAL
LAYOUT GUIDELINES
Feedback Compensation
Figure 7 highlights the voltage-mode control loop for a synchronous-rectified buck converter. The output voltage (V
) is regulated to the Reference voltage level. The
OUT
error amplifier (Error Amp) output (V the oscillator (OSC) triangular wave to provide a pulse­width modulated (PWM) wave with an amplitude of V the PHASE node.
) is compared with
E/A
IN
at
LOAD
8
6. Check Gain against Error Amplifier’s Open-Loop Gain.
7. Estimate Phase Margin - Repeat if Necessary.
Compensation Break Frequency Equations
Figure 8 shows an asymptotic plot of the DC-DC converter’s gain vs frequency. The actual Modulator Gain has a high gain peak due to the high Q factor of the output filter and is not shown in Figure 8. Using the above guidelines should give a Compensation Gain similar to the curve plotted. The open loop error amplifier gain bounds the compensation gain. Check the compensation gain at F the error amplifier. The Closed Loop Gain is constructed on the log-log graph of Figure 8 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.
The compensation gain uses external impedance networks Z
and ZIN to provide a stable, high bandwidth (BW)
FB
with the capabilities of
P2
The PWM wave is smoothed by the output filter (LO and CO). The modulator transfer function is the small-signal transfer function of V
OUT/VE/A
Gain and the output filter (L break frequency at F the modulator is simply the input voltage (V peak-to-peak oscillator voltage ∆V
. This function is dominated by a DC
and CO), with a double pole
O
and a zero at F
LC
OSC
. The DC Gain of
ESR
) divided by the
IN
.
Modulator Break Frequency Equations
The compensation network consists of the error amplifier (internal to the HIP6004B) and the impedance networks Z and Z
. The goal of the compensation network is to provide
FB
a closed loop transfer function with the highest 0dB crossing frequency (f
) and adequate phase margin. Phase margin
0dB
is the difference between the closed loop phase at f 180 degrees. The equations below relate the compensation network’s poles, zeros and gain to the components (R R
, C1, C2, and C3) in Figure 7. Use these guidelines for
3
locating the poles and zeros of the compensation network:
1. Pick Gain (R
2. Place 1
3. Place 2
4. Place 1
ST
ND ST
) for desired converter bandwidth.
2/R1
Zero Below Filter’s Double Pole (~75% FLC).
Zero at Filter’s Double Pole.
Pole at the ESR Zero.
5. Place 2ND Pole at Half the Switching Frequency.
0dB
and
, R2,
1
IN
9
HIP6004B
Modern microprocessors produce transient load rates above 1A/ns. High frequency capacitors initially supply the transient and slow the current load rate seen by the bulk capacitors. The bulk filter capacitor value s are genera lly determined by the ESR (Effective Series Resistance) and voltage rating requirements rather than actual capacitance requirements.
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. For example, Intel recommends that the high frequency decoupling for the Pentium Pro be composed of at least forty (40) 1µF ceramic capacitors in the 1206 surface-mount package.
Use only specialized low-ESR capacitors intended for switching-regulator applications for the bulk capacitors. The bulk capacitor’s ESR will determine 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 (ESL) 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 a suitable component. In most cases, multiple electrolytic capacitors of small case size perform better than a single large case capacitor.
Output Inductor Selection
The output inductor is selected to meet the output voltage ripple requirements and minimize the converter’s response time to the 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 cu rren t are approximated by the following equations:
DI =
Fs x L
- V
V
IN
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 HIP6004B will provide either 0% or 100% duty cycle in response to a load transient. The response time is the time required to slew the inductor current from an initial current value to the transient current level. During this interval the difference between the inductor current and the transient current level must be supplied by the output capacitor. Minimizing the response time can minimize the output capacitance required.
OUT
V
OUT
x
V
IN
DV
OUT
= DI x ESR
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 x I
=
t
RISE
where: I
TRAN
VIN - V
OUT
is the transient load current step, t
TRAN
t
FALL
response time to the application of load, and t
L x I
V
TRAN
OUT
RISE
FALL
is the
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 DACOUT setting. Be sure to check both of these equations at the minimum and maximum output levels for the worst case response time. With a +12V input, and output voltage level equal to DACOUT, t
is the longest response time.
FALL
Input Capacitor Selection
Use a mix of input bypass capacitors to control the voltage overshoot across the MOSFETs. Use small ceramic capacitors for high frequency decoupling and bulk capacitors to supply the current needed each time Q
turns on. Place the
1
small ceramic capacitors physically close to the MOSFETs and between the drain of Q
and the source of Q2.
1
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. 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 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 HIP6004B requires 2 N-Channel power MOSFETs. These 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 both the upper and the lower MOSFETs. These losses are distributed between the two MOSFETs according to duty factor (see the equations
DS(ON)
, gate supply
10
below). Only the upper MOSFET has switching losses, since the Schottky rectifier clamps the switching node before the synchronous rectifier turns on. These equations assume linear voltage-current transitions and do not adequately model power loss due the reverse-recovery of the lower MOSFET’s body diode. The gate-charge losses are dissipated by the HIP6004B and don't heat the MOSFETs. However, large gate-charge increases the switching interval, t
which increases the upper
SW
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.
OUT
1 2
/ VIN,
Io x VIN x tSW x F
S
P P
Where: D is the duty cycle = V
UPPER
LOWER
= Io2 x r
= Io2 x r
t
is the switch ON time, and
SW
is the switching frequency.
F
S
DS(ON)
DS(ON)
x D + x (1 - D)
Standard-gate MOSFETs are normally recommended for use with the HIP6004B. However, logic-level gate MOSFETs can be used under special circumstances. The input voltage, upper gate drive level, and the MOSFET’s absolute gate-to­source 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
. The boot capacitor, C
CC
BOOT
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
) when the lower MOSFET, Q2
D
CC
turns on. Logic-level MOSFETs can only be used if the MOSFET’s absolute gate-to-source voltage rating exceeds the maximum voltage applied to V
+12V
D
BOOT
CC
.
Figure 10 shows the upper gate drive supplied by a direct connection to V converter systems where the main input voltage is +5V
. This option should only be used in
CC
DC
or less. The peak upper gate-to-source voltage is approximately V
less the input supply. For +5V main power and +12VDC
CC
for the bias, the gate-to-source voltage of Q level MOSFET is a good choice for Q MOSFET can be used for Q
if its absolute gate-to-source
2
voltage rating exceeds the maximum voltage applied to V
is 7V. A logic-
1
and a logic-level
1
CC
Schottky Selection
Rectifier D2 is a clamp that catches the negative inductor swing during the dead time between turning off the lower MOSFET and turning on 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 will drop one or two percent as a result. The diode’s rated reverse breakdown voltage must be greater than the maximum input voltage.
.
V
CC
HIP6004B
-
+
BOOT
UGATE PHASE
LGATE PGND
GND
C
11
BOOT
+5V OR +12V
Q1
Q2
NOTE:
NOTE: V
G-S
VCC
HIP6004B
HIP6004B DC-DC Converter Application Circuit
Figure 11 shows an application circuit of a DC-DC Converter for an Intel Pentium Pro microprocessor. Detailed information on the circuit, including a complete Bill-of-Materials and circuit board description, can be found
- 1µHµ
VIN =
+5V
OR
+12V
0.1µF
L
F
1
1
5x 1000µF
0.1µF
SS
V
SEN
RT
VID0 VID1 VID2 VID3 VID4
FB
0.1µF
C
IN
3
1 20 4
5 6 7 8
10
2.2nF
8.2nF
D/A
+12V
PROTECTION
OSC
HIP6004B
+
-
9
20K
MONITOR
V
CC
18
AND
-
+
COMP
2N6394
OVP
19
11
in Application Note AN9672. Although the Application Note details the HIP6004, the same evaluation platform can be used to evaluate the HIP6004B.
2x 1µF
2K
D
1
1000pF
1K
0.1µF
Q
1
Q
2
L
2
3µH
D
2
C
9x 1000µF
OUT
+V
O
12 15
14 13
17 16
GND
2
OCSET PGOOD
BOOT
UGATE PHASE
LGATE PGND
1.33K
15
Component Selection Notes:
C
Each 1000µF 6.3W VDC, Sanyo MV-GX or Equivalent.
OUT -
C
Each 330µF 25W VDC, Sanyo MV-GX or Equivalent.
IN -
- Core: Micrometals T50-52B; Each Winding: 10 Turns of 16A WG.
L
2
L
- Core: Micrometals T50-52; Winding: 5 Turns of 18AWG.
1
D
- 1N4148 or Equivalent.
1
- 3A, 40V Schottky, Motorola MBR340 or Equivalent.
D
2
Q
, Q2 - Intersil MOSFET; RFP70N03.
1
FIGURE 11. PENTIUM PRO DC-DC CONVERTER
12
HIP6004B
Small Outline Plastic Packages (SOIC)
N
INDEX AREA
123
-A­D
e
B
0.25(0.010) C AMB
E
-B-
SEATING PLANE
A
-C-
S
M
0.25(0.010) B
H
α
µ
A1
0.10(0.004)
NOTES:
1. Symbols are defined in the “MO Series Symbol List” in Section
2.2 of Publication Number 95.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension “D” does not include mold flash, protrusions or gate burrs. Mold flash, protrusion and gate burrs shall not exceed
0.15mm (0.006 inch) per side.
4. Dimension “E” does not include interlead flash or protrusions. In­terlead flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual index feature must be located within the crosshatched area.
6. “L” is the length of terminal for soldering to a substrate.
7. “N” is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. The lead width “B”, as measured 0.36mm (0.014 inch) or greater above the seating plane, shall not exceed a maximum value of
0.61mm (0.024 inch)
10. Controlling dimension: MILLIMETER. Converted inch dimen­sions are not necessarily exact.
M
L
h x 45
M
o
M20.3 (JEDEC MS-013-AC ISSUE C)
20 LEAD WIDE BODY SMALL OUTLINE PLASTIC PACKAGE
INCHES MILLIMETERS
SYMBOL
A 0.0926 0.1043 2.35 2.65 -
A1 0.0040 0.0118 0.10 0.30 -
B 0.014 0.019 0.35 0.49 9 C 0.0091 0.0125 0.23 0.32 ­D 0.4961 0.5118 12.60 13.00 3 E 0.2914 0.2992 7.40 7.60 4
e 0.050 BSC 1.27 BSC -
H 0.394 0.419 10.00 10.65 -
h 0.010 0.029 0.25 0.75 5
C
L 0.016 0.050 0.40 1.27 6
N20 207
o
α
0
o
8
o
0
o
8
NOTESMIN MAX MIN MAX
-
Rev. 1 1/02
13
HIP6004B
Thin Shrink Small Outline Plastic Packages (TSSOP)
N
INDEX AREA
123
0.05(0.002)
-A­D
e
b
0.10(0.004) C AM BS
E1
-B-
SEATING PLANE
A
-C-
M
0.25(0.010) BM M
E
α
A1
0.10(0.004)
GAUGE
PLANE
0.25
0.010
A2
L
c
NOTES:
1. These package dimensions are within allowable dimensions of JEDEC MO-153-AC, Issue E.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension “D” does not include mold flash, protrusions or gate burrs. Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006 inch) per side.
4. Dimension “E1” does not include interlead flash or protrusions. Inter­lead flash and protrusions shall not exceed 0.15mm (0.006 inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual index feature must be located within the crosshatched area.
6. “L” is the length of terminal for soldering to a substrate.
7. “N” is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. Dimension “b” does not include dambar protrusion. Allowable dambar protrusion shall be 0.08mm (0.003 inch) total in excess of “b” dimen­sion at maximum material condition. Minimum space between protru­sion and adjacent lead is 0.07mm (0.0027 inch).
10. Controlling dimension: MILLIMETER. Converted inch dimensions are not necessarily exact. (Angles in degrees)
M20.173
20 LEAD THIN SHRINK SMALL OUTLINE PLASTIC PACKAGE
INCHES MILLIMETERS
SYMBOL
A - 0.047 - 1.20 ­A1 0.002 0.006 0.05 0.15 ­A2 0.031 0.051 0.80 1.05 -
b 0.0075 0.0118 0.19 0.30 9
c 0.0035 0.0079 0.09 0.20 -
D 0.252 0.260 6.40 6.60 3 E1 0.169 0.177 4.30 4.50 4
e 0.026 BSC 0.65 BSC -
E 0.246 0.256 6.25 6.50 -
L 0.0177 0.0295 0.45 0.75 6
N20 207
o
α
0
o
8
o
0
o
8
Rev. 1 6/98
NOTESMIN MAX MIN MAX
-
14
HIP6004B
Quad Flat No-Lead Plastic Package (QFN) Micro Lead Frame Plastic Package (MLFP)
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data she ets are current before placin g orders. Information furn ished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or othe rwise under any patent or patent righ ts of Intersil or its subsidiaries.
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15
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