ISL6225
S
DESIGN
R NEW
O
F
D
:
E
T
ND
EN
LACEM
C OM ME
N O T R E MME N D E D R E P
RECO
ISL6227
DATASHEET
FN9049
Rev 7.00
December 28, 2004
Dual Mobile-Friendly PWM Controller with DDR Memory Option
The ISL6225 dual PWM controller delivers high efficiency and
tight regulation from two voltage regulating synchronous buck
DC/DC converters. The ISL6225 PWM power supply controller
was designed especially for DDR DRAM, SDRAM, and graphic
chipset applications in high performance desknote PCs,
notebook PCs, sub-notebook PCs, and PDAs.
Features
Automatic mode selection of constant-frequency synchronous
rectification at heavy load, and hysteretic diode-emulation at
light load, assure high efficiency over a wide range of
conditions. The hysteretic mode of operation can be disabled
separately on each PWM converter if constant-frequency
continuous-conduction operation is desired for all load levels.
Efficiency is further enhanced by using the lower MOSFET
rDS(ON) as the current sense element.
• Complete DDR memory power solution
- VTT tracks VDDQ/2
- VDDQ/2 buffered reference output
Voltage-feed-forward ramp modulation, average current mode
control, and internal feedback compensation provide fast
response to input voltage and output load transients. Input
current ripple is minimized by channel to channel PWM
phase shift of 0°, 90°, or 180° determined by input voltage
and status of the DDR pin.
The ISL6225 can control two independent output voltages
adjustable from 0.9V to 5.5V or, by activating the DDR pin,
transform into a complete DDR memory power supply
solution. In DDR mode, CH2 output voltage VTT tracks CH1
output voltage VDDQ. CH2 output can both source and sink
current, an essential power supply feature for DDR memory
systems. The reference voltage VREF required by DDR
memory is generated as well.
In dual power supply applications the ISL6225 monitors the
output voltage of both CH1 and CH2. An independent
PGOOD (power good) signal is asserted for each channel
after the soft-start sequence has completed, and the output
voltage is within ±10% of the set point. In DDR mode CH1
generates the only PGOOD signal.
Built-in overvoltage protection prevents the output from
going above 115% of the set point by holding the lower
MOSFET on and the upper MOSFET off. When the output
voltage decays below the overvoltage threshold, normal
operation automatically resumes. Once the soft-start
sequence has completed, under-voltage protection may
latch the ISL6225 off if either output drops below 75% of its
set point value.
Adjustable overcurrent protection (OCP) monitors the
voltage drop across the rDS(ON) of the lower MOSFET. If
more precise current-sensing is required, an external current
sense resistor may be used.
FN9049 Rev 7.00
December 28, 2004
• Provides regulated output voltage in the range of 0.9V-5.5V
- High efficiency over wide load range
- Synchronous buck converter with hysteretic operation at
light load
- Inhibit Hysteretic mode on one, or both channels
• No current-sense resistor required
- Uses MOSFET rDS(ON)
- Optional current-sense resistor for precision overcurrent
• Under-voltage lock-out on VCC pin
• Dual input voltage mode operation
- Operates directly from battery 5V to 24V input
- Operates from 3.3V or 5V system rail
- VCC from 5V only
• Excellent dynamic response
- Combined voltage feed-forward and average current
mode control
• Power-good signal for each channel
• 300kHz switching frequency
- 180° channel to channel phase operation for reduced input
ripple when not in DDR mode
- 0° channel to channel phase operation in DDR mode for
reduced channel interference
- 90° channel to channel phase operation for reduced input
ripple in DDR mode when VIN is at GND.
• Pb-Free Available (RoHS Compliant)
Applications
• Mobile PCs
• PDAs
• Hand-held portable instruments
Ordering Information
PART NUMBER
TEMP. (°C)
PACKAGE
PKG.
DWG. #
28 Ld SSOP
M28.15
ISL6225CA
-10 to 85
ISL6225CAZ (Note 1)
-10 to 85
28 Ld SSOP (Pb-free) M28.15
ISL6225CAZA (Note 1)
-10 to 85
28 Ld SSOP (Pb-free) M28.15
NOTES:
1. Intersil Pb-free products employ special Pb-free material sets; molding
compounds/die attach materials and 100% matte tin plate termination
finish, which are RoHS compliant and compatible with both SnPb and
Pb-free soldering operations. Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed
the Pb-free requirements of IPC/JEDEC J STD-020.
2. Add “-T” for Tape and Reel.
Page 1 of 19
ISL6225
Pinout
ISL6225
SSOP-28
TOP VIEW
GND
1
28 VCC
LGATE1
2
27 LGATE2
PGND1
3
26 PGND2
PHASE1
4
25 PHASE2
UGATE1
5
24 UGATE2
BOOT1
6
23 BOOT2
ISEN1
7
22 ISEN2
EN1
8
21 EN2
VOUT1
9
20 VOUT2
VSEN1 10
19 VSEN2
OCSET1 11
SOFT1 12
DDR 13
VIN 14
FN9049 Rev 7.00
December 28, 2004
18 OCSET2
17 SOFT2
16 PG2/REF
15 PG1
Page 2 of 19
ISL6225
Absolute Maximum Ratings
Thermal Information
Bias Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+ 6.5V
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +27.0V
PHASE, UGATE Voltage . . . . . . . . . . . . . . GND-5V (Note 3) to 33V
BOOT, ISEN Voltage . . . . . . . . . . . . . . . . . . . . GND-0.3V to +33.0V
BOOT with respect to PHASE . . . . . . . . . . . . . . . . . . . . . . . . .+ 6.5V
All Other Pins . . . . . . . . . . . . . . . . . . . . . . GND -0.3V to VCC + 0.3V
ESD Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Class 2
Thermal Resistance (Typical, Note 4)
JA (°C/W)
SSOP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . .
78
Maximum Junction Temperature (Plastic Package) . . . . . . . . 150°C
Maximum Storage Temperature Range . . . . . . . . . . . -65°C to 150°C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C
(SSOP - Lead Tips Only)
Recommended Operating Conditions
Bias Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +5.0V 5%
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . +5.0V to +24.0V
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . .-10°C to 85°C
Junction Temperature Range. . . . . . . . . . . . . . . . . . .-10°C to 125°C
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.
NOTES:
3. 200ns transient.
4. JA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
Electrical Specifications
PARAMETER
Recommended Operating Conditions, Unless Otherwise Noted.
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
ICC
LGATEx, UGATEx Open, VSENx forced above
regulation point, DDR = 0, VIN > 5V
-
2.2
3.2
mA
ICCSN
-
-
30
A
Rising VCC Threshold
VCCU
4.3
4.65
4.75
V
Falling VCC Threshold
VCCD
4.1
4.35
4.45
V
IVIN
10
-
30
A
Input Voltage Pin Current (Source)
IVINO
-
-15
-30
A
Shut-down Current
IVINS
-
-
1
A
PWM1 Oscillator Frequency
FC
255
300
345
kHz
Ramp Amplitude, pk-pk
VR1
VIN = 16V, by design
-
2
-
V
Ramp Amplitude, pk-pk
VR2
VIN = 5V, by design
-
1.25
-
V
VCC SUPPLY
Bias Current
Shut-down Current
VCC UVLO
VIN
Input Voltage Pin Current (Sink)
OSCILLATOR
Ramp Offset
VROFF
By design
-
0.5
-
V
Ramp/VIN Gain
GRB1
VIN 3V, by design
-
125
-
mV/V
Ramp/VIN Gain
GRB2
1VIN 3V, by design
-
250
-
mV/V
-
0.9
-
V
-1.0
-
+1.0
%
-
-5
-
A
-
1.5
-
V
REFERENCE AND SOFT-START
Internal Reference Voltage
VREF
Reference Voltage Accuracy
Soft-Start Current During Start-up
Soft-Start Complete Threshold
FN9049 Rev 7.00
December 28, 2004
ISOFT
VST
By design
Page 3 of 19
ISL6225
Electrical Specifications
Recommended Operating Conditions, Unless Otherwise Noted. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
0.0mA < IVOUT1 < 5.0A; 5.0V < VBATT < 24.0V
-2.0
-
+2.0
%
PWM CONVERTERS
Load Regulation
VSEN pin bias current
IVSEN
By design
50
80
120
nA
VOUT pin input impedance
IVOUT
VOUT = 5V
40
55
65
k
Undervoltage Shut-Down Level
VUVL
Fraction of the set point; ~2s noise filter
70
-
85
%
Overvoltage Shut-Down
VOVP1
Fraction of the set point; ~2s noise filter
110
-
130
%
GATE DRIVERS
Upper Drive Pull-Up Resistance
R2UGPUP
VCC = 4.5V
-
8
15
Upper Drive Pull-Down Resistance
R2UGPDN
VCC = 4.5V
-
3.2
5
Lower Drive Pull-Up Resistance
R2LGPUP
VCC = 4.5V
-
8
15
Lower Drive Pull-Down Resistance
R2LGPDN
VCC = 4.5V
-
1.8
3
POWER GOOD AND CONTROL FUNCTIONS
Power Good Lower Threshold
VPG-
Fraction of the set point; ~3s noise filter
-13
-
-7
%
Power Good Higher Threshold
VPG+
Fraction of the set point; ~3s noise filter.
Guaranteed by design.
12
-
16
%
IPGLKG
VPULLUP = 5.5V
-
-
1
A
VPGOOD
IPGOOD = -4mA
-
0.5
0.85
V
EN - Low (Off)
-
-
0.8
V
EN - High (On)
2.5
-
-
V
-
-
0.1
V
0.9
-
-
V
DDR - Low (Off)
-
-
0.8
V
DDR - High (On)
2.5
-
-
V
0.99*
VOC2
VOC2
1.01*
VOC2
V
-
10
16
mA
PGOODx Leakage Current
PGOODx Voltage Low
CCM Enforced (Hysteretic Operation
Inhibited)
VOUTX pulled low
Automatic CCM/Hysteretic Operation Enabled
VOUTX connected to the output
DDR REF Output Voltage
VDDREF
DDR = 1, IREF = 0...10mA
DDR REF Output Current
IDDREF
DDR = 1. Guaranteed by design.
FN9049 Rev 7.00
December 28, 2004
Page 4 of 19
ISL6225
Functional Pin Description
GND (Pin 1)
Signal ground for the IC.
LGATE1, LGATE2 (Pin 2, 27)
These are outputs of the lower MOSFET drivers.
PGND1, PGND2 (Pin 3, 26)
These pins provide the return connection for lower gate
drivers. These pins are connected to sources of the lower
MOSFETs of their respective converters.
PHASE1, PHASE2 (Pin 4, 25)
The PHASE1 and PHASE2 points are the junction points of
the upper MOSFET sources, output filter inductors, and
lower MOSFET drains. Connect these pins to the respective
converter’s upper MOSFET source.
UGATE1, UGATE2 (Pin 5, 24)
These pins provide the gate drive for the upper MOSFETs.
BOOT1, BOOT2 (Pin 6, 23)
These pins power the upper MOSFET drivers of the PWM
converter. Connect this pin to the junction of the bootstrap
capacitor with the cathode of the bootstrap diode. Anode of
the bootstrap diode is connected to the VCC pin.
ISEN1, ISEN2 (Pin 7, 22)
These pins are used to monitor the voltage drop across the
lower MOSFET for current feedback and overcurrent
protection. For precise current detection these inputs can be
connected to the optional current sense resistors placed in
series with the source of the lower MOSFETs.
EN1, EN2 (Pin 8, 21)
These pins enable operation of the respective converter
when high. When both pins are low, the chip is disabled and
only low leakage current <1A is taken from VCC and VIN.
These pins are to be connected together and switched at the
same time.
VOUT1, VOUT2 (Pin 9, 20)
These pins when connected to the converters’ respective
outputs provide the output voltage inside the chip to reduce
output voltage excursion during HYS/PWM transition. When
connected to ground, these pins command forced
converters operate in continuous conduction mode at all
load levels.
VSEN1, VSEN2 (Pin 10, 19)
These pins are connected to the resistive dividers that set
the desired output voltage. The PGOOD, UVP, and OVP
circuits use this signal to report output voltage status.
SOFT1, SOFT2 (Pin 12, 17)
These pins provide soft-start function for their respective
controllers. When the chip is enabled, the regulated 5A
pull-up current source charges the capacitor connected from
the pin to ground. The output voltage of the converter follows
the ramping voltage on the SOFT pin.
DDR (Pin 13)
This pin, when high, transforms dual channel chip into
complete DDR memory solution. The OCSET2 pin becomes
an input to provide the required tracking function. The
channel synchronization is changed from out-of-phase to inphase. The PG2/REF pin becomes the output of the VDDQ/
2 buffered voltage that is used as a reference voltage by the
second channel.
VIN (Pin 14)
Provides battery voltage to the oscillator for feed-forward
rejection of the input voltage variation.
When connected to ground via 100k resistor while the
DDR pin is high, this pin commands the out-of-phase 90o
channels synchronization for reduced inter-channel
interference.
PG1 (Pin 15)
PGOOD1 is an open drain output used to indicate the status
of the output voltage. This pin is pulled low when the first
channel output is not within ±10% of the set value.
PG2/REF (Pin 16)
This pin has a double function depending on the mode the
chip is operating. When the chip is used as a dual channel
PWM controller (DDR = 0), the pin provides a PGOOD2
function for the second channel. The pin is pulled low when
the second channel output is not within ±10% of the set value.
In DDR mode (DDR = 1), this pin serves as an output of the
buffer amplifier that provides VDDQ/2 reference voltage
applied to the OCSET2 pin.
OCSET2 (Pin 18)
In a dual channel application (DDR = 0), a resistor from this
pin to ground sets the overcurrent threshold for the second
controller.
In the DDR application (DDR = 1), this pin sets the output
voltage of the buffer amplifier and the second controller and
should be connected to the center point of a divider from the
VDDQ output.
VCC (Pin 28)
This pin powers the controller.
OCSET1 (Pin 11)
A resistor from this pin to ground sets the overcurrent
threshold for the first controller.
FN9049 Rev 7.00
December 28, 2004
Page 5 of 19
ISL6225
Generic Application Circuits
ENABLE
OCSET1
Q1
L1
VOUT1
PWM1
C1
Q2
+VIN
EN1
+3.3V TO +24V
EN2
+
Q3
VCC
DDR
+5V
+1.80V
L2
VOUT2
PWM2
OCSET2
C2
Q4
+1.20V
+
FIGURE 1. ISL6225 APPLICATION CIRCUIT FOR TWO CHANNEL POWER SUPPLY
ENABLE
OCSET1
Q1
L1
PWM1
Q2
+VIN
C1
VDDQ
+2.50V
+
EN1
EN2
+3.3V TO +24V
Q3
VCC
DDR
+5V
PG2/VREF
PWM2
L2
VTT
OCSET2
Q4
C2
+
+1.25V
VREF
+1.25V
FIGURE 2. ISL6225 APPLICATION CIRCUIT FOR COMPLETE DDR MEMORY POWER SUPPLY
FN9049 Rev 7.00
December 28, 2004
Page 6 of 19
BOOT1
PG1
SOFT1
VCC GND
EN1 VOUT1
VOUT2
EN2
REF/PG2
BOOT2
SOFT2
UGATE2
UGATE1
PHASE1
DDR=1
ADAPTIVE DEAD-TIME
DIODE EMULATION
V/I SAMPLE TIMING
PGND1
PHASE2
ADAPTIVE DEAD-TIME
DIODE EMULATION
V/I SAMPLE TIMING
DDR=0
PWM/HYS TRANSITION
PGND2
PWM/HYS TRANSITION
LGATE1
LGATE2
VCC
VCC
POR
+
MODE CHANGE COMP 1
+
MODE CHANGE COMP 2
ENABLE
-
HYSTERETIC COMPARATOR 1
-
SAME STATE FOR
8 CLOCK CYCLES
REQUIRED TO CHANGE
PWM OR HYS MODE
SAME STATE FOR
8 CLOCK CYCLES
REQUIRED TO CHANGE
PWM OR HYS MODE
BIAS SUPPLIES
REFERENCE
-
- HYSTERETIC COMPARATOR 2
FAULT LATCH
+
VHYS=15mV
VHYS=15mV
+
SOFT-START
300k
-
1M
500k
1.3pF
OC1 DDR OC2
ERROR AMP 1
0.9V REFERENCE
15.2pF
VOLTS/SEC
CLAMP
1.3pF
+
+
OV UV
PGOOD
DDR MODE
CONTROL
VOLTS/SEC
CLAMP
500k
VSEN1
OV UV
PGOOD
15.2pF
1M
-
PWM1
PWM2
+
+
DDR EN1 EN2
100
0
1
1
+
DDR=0
0.9V REFERENCE
-
CURRENT
SAMPLE
+
1
CURRENT
SAMPLE
1
1
VIN
CH1CH2
0 24.0V
180º
4.2 VIN 24.0V
0º
VIN to GND
90º
VSEN2
ERROR AMP 2
DUTY CYCLE RAMP GENERATOR
PWM CHANNEL PHASE CONTROL
ISEN1
300k
-
+
100
CURRENT
SAMPLE
DDR=0
0.9V REFERENCE
0.9V REFERENCE
OCSET2
+
DDR=1
Page 7 of 19
-
OC2
OC1
+
1/3
OCSET1
ISEN2
CURRENT
SAMPLE
+
OCSET1
+
DDR=1
1/32
ISEN1
SAME STATE FOR
8 CLOCK CYCLES
REQUIRED TO LATCH
OVER-CURRENT FAULT
+
VIN
DDR
VCC
SAME STATE FOR
8 CLOCK CYCLES
REQUIRED TO LATCH
OVER-CURRENT FAULT
1/32
ISEN2
+
DDR VREF
BUFFER AMP
1/3
OCSET2
+
DDR VTT
REFERENCE
ISL6225
FN9049 Rev 7.00
December 28, 2004
Block Diagram
ISL6225
Description
Operation
The ISL6225 is a dual channel PWM controller intended for
use in power supplies for graphic chipset, SDRAM, DDR
DRAM or other low voltage power applications in modern
notebook and sub-notebook PCs. The IC integrates two
control circuits for two synchronous buck converters. The
output voltage of each controller can be set in the range of
0.9V to 5.5V by an external resistive divider. Out-of-phase
operation with 180 degree phase shift reduces input current
ripple.
The synchronous buck converters can operate from either
an unregulated DC source such as a notebook battery with a
voltage ranging from 5.0V to 24V, or from a regulated system
rail of 3.3V or 5V. In either mode of operation the controller is
biased from the +5V source.
The controllers operate in the current mode with input
voltage feed-forward for simplified feedback loop
compensation and reduced effect of the input voltage
variation. An integrated feedback loop compensation
dramatically reduces the number of external components.
Depending on the load level, converters can operate either
in a fixed-frequency mode or in a hysteretic mode. Switchover to the hysteretic mode operation at light loads improves
the converters' efficiency and prolongs battery run time. The
hysteretic mode of operation can be inhibited independently
for each channel if a variable frequency operation is not
desired.
The ISL6225 has a special means to rearrange its internal
architecture into a complete DDR solution. When DDR input
is set high, the second channel can provide the capability to
track the output voltage of the first channel. The buffered
reference voltage required by DDR memory chips is also
provided.
Initialization
The Power-On Reset (POR) function continually monitors
the bias supply voltage on the VCC pin and initiates soft-start
operation after the input supply voltage exceeds 4.5V.
Should this voltage drop lower than 4.0V, the POR disables
the chip.
Soft-Start
When soft-start is initiated, the voltage on the SOFT pin
starts to ramp gradually due to the 5A current sourced into
the external soft-start capacitor. The output voltage starts to
follow the soft-start voltage.
When the SOFT pin voltage reaches a level of 0.9V, the
output voltage comes into regulation while the soft-start pin
voltage continues to rise. When the SOFT voltage reaches
FN9049 Rev 7.00
December 28, 2004
1.5V, the power good (PGOOD), the mode control, and the
fault functions are enabled, as depicted in Figure 3.
EN
1
0.9V
1.5V
SOFT
2
VOUT
3
PGOOD
4
Ch1 5.0V
Ch3 1.0V
Ch2 2.0V
Ch4 5.0V
M1.00ms
FIGURE 3. START UP
This completes the soft-start sequence. Further rise of pin
voltage does not affect the output voltage. During the softstart, the converter always operates in continuous
conduction mode independently of the load level or FCCM
pin potential.
The soft-start time (the time from the moment when EN
becomes high to the moment when PGOOD is reported) is
determined by the following equation.
1.5V Csoft
T SOFT = ---------------------------------5A
The time it takes the output voltage to come into regulation
can be obtained from the following equation.
T RISE = 0.6 TSOFT
Having such a spread between the time when the output
voltage reaches the regulation point and the moment when
PGOOD is reported allows for a fault-safe test mode by
means of an external circuit that clamps the SOFT pin
voltage on the level 0.9V < VSOFT < 1.5V.
Output Voltage Program
The output voltage of either channel is set by a resistive divider
from the output to ground. The center point of the divider is
connected to VSEN pin as shown in Figure 4. The output
voltage value is determined by the following equation.
0.9V R1 + R2
V O = ---------------------------------------------R2
Where 0.9V is the value of the internal reference. The VSEN
pin voltage is also used by the controller for the power good
function and to detect Undervoltage and Overvoltage
conditions.
Page 8 of 19
ISL6225
Automatic Operation Mode Control
In nominal currents the synchronous buck converter
operates in continuous-conduction constant-frequency
mode. This mode of operation achieves higher efficiency
due to the substantially lower voltage drop across the
synchronous MOSFET compared to a Schottky diode.
In contrast, continuous-conduction operation with load
currents lower than the inductor critical value results in lower
efficiency. In this case, during a fraction of a switching cycle,
the direction of the inductor current changes to the opposite,
actively discharging the output filter capacitor.
VIN
L1
ISEN
RCS
LGATE
C1
Cz
Q2
R1
VOUT
VSEN
OCSET
ISL6225
To prevent chatter between operating modes, the circuit
looks for eight contiguous signals of the same polarity before
it makes the decision to perform a mode change. The same
algorithm is true for both CCM-hysteretic and hystereticCCM transitions.
Hysteretic Operation
Q1
UGATE
The voltage across the synchronous MOSFET at the
moment of time just before the upper-MOSFET turns on is
monitored for purposes of mode change. When the
converter operates at currents higher than critical, this
voltage is always negative. In currents lower than critical, the
voltage is always positive. The mode control circuit uses a
sign of voltage across the synchronous devices to determine
if the load current is higher or lower than the critical value.
When the critical inductor current is detected, the converter
enters hysteretic mode. The PWM comparator and the error
amplifier that provided control in the CCM mode are inhibited
and the hysteretic comparator is now activated. A change is
also made to the gate logic. In hysteretic mode the
synchronous rectifier MOSFET is controlled in diode
emulation mode, hence conduction in the second quadrant
is prohibited.
R2
ROC
VOUT
t
FIGURE 4. OUTPUT VOLTAGE PROGRAM
To maintain the output voltage in regulation, the discharged
energy should be restored during the consequent cycle of
operation by the cost of increased circulating current and
losses associated with it.
The critical value of the inductor current can be estimated by
the following expression:
IIND
PHASE
COMP
t
1 2 3 4 5 6 7 8
MODE
OF
OPERATION
V IN – V O V O
I HYS = ----------------------------------------------------2 F SW L O V IN
To improve converter efficiency at loads lower than critical,
the switch-over to variable frequency hysteretic operation
with diode emulation is implemented into the PWM scheme.
The switch-over is provided automatically by the mode
control circuit that constantly monitors the inductor current
and alters the way the PWM signal is generated.
t
HYSTERETIC
PWM
t
FIGURE 5. CCM - HYSTERETIC TRANSITION
VOUT
t
IIND
1
2 3 4 5
t
6 7 8
PHASE
COMP
t
MODE
OF
OPERATION
HYSTERETIC
PWM
t
FIGURE 6. HYSTERETIC - CCM TRANSITION
FN9049 Rev 7.00
December 28, 2004
Page 9 of 19
ISL6225
The hysteretic comparator initiates the PWM signal when the
output voltage gets below the lower threshold and
terminates the PWM signal when the output voltage rises
above the upper threshold. A spread or hysteresis between
these two thresholds determines the switching frequency
and the peak value of the inductor current. The transition to
constant frequency CCM mode happens when the inductor
current increases above the critical value:
V hys
I CCM ---------------------2 ESR
Where, Vhys= 15mV, is a hysteretic comparator window,
ESR is the equivalent series resistance of the output
capacitor. Because of different control mechanisms, the
value of the load current where transition into CCM
operation takes place is usually higher compared to the load
level at which transition into hysteretic mode had occurred.
VOUT pin and Forced Continuous
Conduction Mode (FCCM)
The controller has the flexibility to operate a converter in
fixed-frequency constant conduction mode (CCM), or in
hysteretic mode. Connecting the VOUT pin to GND will inhibit
hysteretic mode; this is called forced constant conduction
mode (FCCM). Connecting the VOUT pin to the converter
output will allow transition between CCM mode and
hysteretic mode.
an internal current control loop. The resistor connected to
the ISEN pin sets the gain in the current feedback loop. The
following expression estimates the required value of the
current sense resistor depending on the maximum load
current and the value of the MOSFET’s rDS(ON).
I MAX r DS ON
R CS = ---------------------------------------------- – 100
75A
Due to implemented current feedback, the modulator has a
single pole response with -1 slope at a frequency
determined by the load,
1
F PO = ---------------------------------2 R O C O
where: Ro is load resistance and Co is load capacitance. For
this type of modulator, a Type 2 compensation circuit is
usually sufficient.
Figure 7 shows a Type 2 amplifier and its response along
with the responses of the current mode modulator and the
converter. The Type 2 amplifier, in addition to the pole at
origin, has a zero-pole pair that causes a flat gain region at
frequencies between the zero and the pole:
1
F Z = ------------------------------- = 6kHz
2 R 2 C 1
;
When the VOUT pin is connected to the converter output, a
circuit is activated that smooths the transition from hysteretic
mode to CCM mode. While in hysteretic mode, this circuit
prepositions the PWM error amplifier output to a level close
to that needed to provide the appropriate PWM duty cycle
required for regulation. This is a much more desirable state
for the PWM error amplifier at mode transition, as opposed
to being in saturation which requires a period of time to slew
to the required level.
1
F P = ------------------------------- = 600kHz
2 R 1 C 2
This region is also associated with phase ‘bump’ or
reduced phase shift. The amount of phase shift reduction
depends on how wide the region of flat gain is and has a
maximum value of 90o. To further simplify the converter
compensation, the modulator gain is kept independent of
the input voltage variation by providing feed-forward of VIN
to the oscillator ramp.
Such dual function of the VOUT pin enhances applicability of
the controller and allows for lower pin count.
C2
R2
CONVERTER
Feedback Loop Compensation
To reduce the number of external components and remove
the burden of determining compensation components from a
system designer, both PWM controllers have internally
compensated error amplifiers. To make internal
compensation possible several design measures where
taken.
First, the ramp signal applied to the PWM comparator is
proportional to the input voltage provided via the VIN pin.
This keeps the modulator gain constant when the input
voltage varies. Second, the load current proportional signal
is derived from the voltage drop across the lower MOSFET
during the PWM time interval and is added to the amplified
error signal on the comparator input. This effectively creates
FN9049 Rev 7.00
December 28, 2004
C1
R1
EA
TYPE 2 EA
GM = 18dB
GEA = 14dB
MODULATOR
FZ
FPO
FP
FC
FIGURE 7. FEEDBACK LOOP COMPENSATION
Page 10 of 19
ISL6225
The zero frequency, the amplifier high-frequency gain, and
the modulator gain are chosen to satisfy most typical
applications. The crossover frequency will appear at the
point where the modulator attenuation equals the amplifier
high frequency gain. The only task that the system designer
has to complete is to specify the output filter capacitors to
position the load main pole somewhere within one decade
lower than the amplifier zero frequency. With this type of
compensation plenty of phase margin is easily achieved due
to zero-pole pair phase ‘boost’. Conditional stability may
occur only when the main load pole is positioned too much
to the left side on the frequency axis due to excessive output
filter capacitance. In this case, the ESR zero placed within
10kHz...50kHz range gives some additional phase ‘boost’.
Some phase boost can also be achieved by connecting
capacitor Cz in parallel with the upper resistor R1 of the
divider that sets the output voltage value, as shown in
Figure 4.
Gate Control Logic
The gate control logic translates generated PWM signals
into gate drive signals providing necessary amplification,
level shift, and shoot-trough protection. Also, it bears some
functions that help to optimize the IC performance over a
wide range of the operational conditions. As MOSFET
switching time can very dramatically from type to type and
with the input voltage, the gate control logic provides
adaptive dead time by monitoring real gate waveforms of
both the upper and the lower MOSFETs.
Dual-Step Conversion
The ISL6225 dual channel controller can be used either in
power systems with a single-stage power conversion when
the battery power is converted into the desired output
voltage in one step, or in the systems where some
intermediate voltages are initially established. The choice of
the approach may be dictated by the overall system design
criteria or simply to be a matter of voltages available to the
system designer, like in the case of PCI card applications.
When the power input voltage is a regulated 5V or 3.3V
system bus, the feed-forward ramp may become too
shallow, which creates the possibility of duty-factor jitter
especially in a noisy environment. The noise susceptibility
when operating from low level regulated power sources can
be improved by connecting the VIN pin to ground. The feedforward ramp generator will be internally reconnected from
the VIN pin to the VCC pin and the ramp slew rate will be
doubled. Application circuits for dual-step power conversion
are presented in Figures 11 through 15.
Protections
The converter output is monitored and protected against
extreme overload, short circuit, Overvoltage, and
Undervoltage conditions.
A sustained overload on the output sets the PGOOD low and
latches-off the whole chip. The controller operation can be
restored by cycling the VCC voltage or an enable (EN) pin.
Overcurrent Protection
Both PWM controllers use the lower MOSFET’s
on-resistance {rDS(ON)} to monitor the current for protection
against shorted outputs. The sensed current from the ISEN
pin is compared with a current set by a resistor connected
from the OCSET pin to ground.
9.6V R CS + 100
R OCSET = ---------------------------------------------------------I OC R
DS ON
Where, IOC is a desired overcurrent protection threshold and
RCS is the value of the current sense resistor connected to
the ISEN pin.
If the lower MOSFET current exceeds the overcurrent
threshold, a pulse skipping circuit is activated. The upper
MOSFET will not be turned on as long as the sensed
current is higher then the threshold value. This limits the
current supplied by the DC voltage source. This condition
keeps on for eight clock cycles after the overcurrent
comparator was tripped for the first time. If after these first
eight clock cycles the current exceeds the overcurrent
threshold again in a time interval of another eight clock
cycles, the overcurrent protection latches and disables the
chip. If the overcurrent condition goes away during the first
eight clock cycles, normal operation is restored and the
overcurrent circuit resets itself sixteen clock cycles after the
overcurrent threshold was exceeded the first time, Figure 8.
PGOOD
1
8 CLK
IL
SHUTDOWN
2
VOUT
3
CH1 5.0V
CH3 1.0A
CH2 100mV
M 10.0µs
FIGURE 8. OVERCURRENT PROTECTION WAVEFORMS
FN9049 Rev 7.00
December 28, 2004
Page 11 of 19
ISL6225
If load step is strong enough to pull output voltage lower
than the undervoltage threshold, the chip shuts down
immediately.
Because of the nature of the used current sensing
technique, and to accommodate wide range of the rDS(ON)
variation, the value of the overcurrent threshold should
represent overload current about 150%...180% of the
nominal value. If more precise current protection is desired,
a current sense resistor placed in series with the lower
MOSFET source may be used.
Overvoltage Protection
Should the output voltage increase over 115% of the normal
value due to the upper MOSFET failure, or other reasons,
the overvoltage protection comparator will force the
synchronous rectifier gate driver high. This action actively
pulls down the output voltage and eventually attempts to
blow the battery fuse. As soon as the output voltage drops
below the threshold, the OVP comparator is disengaged.
This OVP scheme provides a ‘soft’ crowbar function which
helps to tackle severe load transients and does not invert the
output voltage when activated - a common problem for OVP
schemes with a latch.
Over-Temperature Protection
The chip incorporates an over-temperature protection circuit
that shuts the chip down when the die temperature of 150°C
is reached. Normal operation restores at die temperatures
below 125°C through the full soft-start cycle.
DDR Application
Double Data Rate (DDR) memory chips are expected to take
the place of traditional memory in many newly designed
computers, including high-end notebooks, due to increased
throughput. A novel feature associated with this type of
memory is new referencing and data bus termination
techniques. These techniques employ a reference voltage,
VREF, that tracks the center point of VDDQ and VSS
voltages and an additional VTT power source to which all
terminating resistors are connected. Despite the additional
power source, the overall memory power consumption is
reduced compared to traditional termination.
The added power source has a cluster of requirements that
should be observed and considered. Due to reduced
differential thresholds of DDR memory, the termination
power supply voltage, VTT, shall closely track VDDQ/2
voltage. Another very important feature for the termination
power supply is a capability to equally operate in sourcing
and sinking modes. The VTT supply shall regulate the output
voltage with the same degree of precision when current is
floating from the supply to the load and when the current is
diverted back from the load into the power supply. The last
mode of operation usually conflicts with the way most PWM
controllers operate.
FN9049 Rev 7.00
December 28, 2004
The ISL6225 dual channel PWM controller possesses
several important means that allow reconfiguration for this
particular application and provide all three voltages required
in DDR memory-compliant computer.
To reconfigure the ISL6225 for a complete DDR solution, the
DDR pin shall be permanently set high. The simplest way to
do that is to connect it to the VCC rail. This activates some
functions inside the chip that are specific to the DDR
memory power needs.
In the DDR application presented in Figures 14 and 15, the
first controller regulates the VDDQ rail to 2.5V. The output
voltage is set by an external divider R3 and R5. The second
controller regulates the VTT rail to VDDQ/2. The OCSET2
pin function is now different. The pin serves now as an input
that brings VDDQ/2 voltage created by R4 and R6 divider
inside the chip. That effectively provides a tracking function
for the VTT voltage.
The PG2 pin function is also different in DDR mode. This pin
becomes the output of the buffer, which input is connected
via the OCSET2 pin to the center point of the R/R divider
from the VDDQ output. The buffer output voltage serves as
1.25V reference for the DDR memory chips. Current
capability of this pin is about 10mA.
For the VTT channel some control and protective functions
can be significantly simplified as this output is derived from
the VDDQ output. For example, the overcurrent and
overvoltage protections for the second controller are
disabled when the DDR pin is set high. The hysteretic mode
of operation is also disabled on the VTT channel to allow
sinking capability to be independent from the load level. As
the VTT channel tracks the VDDQ/2 voltage, the soft-start
function is not required and the SOFT2 pin may be left open.
Channel Synchronization in DDR
Applications
Presence of two PWM controllers on the same die require
channel synchronization to reduce inter channel interference
that may cause the duty factor jitter and increased output
ripple. The PWM controller is mostly susceptible to noise
when an error signal on the input of the PWM comparator
approaches the decision making point. False triggering can
occur causing jitter and affecting the output regulation.
Out-of-phase operation is a common approach to
synchronize dual channel converters as it reduces an input
current ripple and provides a minimum interference for
channels that control different voltage levels. When used in
DDR application with cascaded converters (VTT generated
from VDDQ), the turn-on of the upper MOSFET in the VDDQ
channel happens to be just before the decision making point
in the VTT channel that is running with a duty-factor close to
50%, as in Figure 10.
Page 12 of 19
ISL6225
This makes out-of-phase channel synchronization
undesirable when one of the channels is running on a dutyfactor of 50%. Inversely, the in-phase channel arrangement
does not have this drawback. Points of decision are far from
noisy moments of time in both sourcing and sinking modes
of operation for VIN = 7.5V to 24V as it is shown in Figure 9.
In the case when power for VDDQ is taken from the +5V
system rail, as Figure 10 shows, both in-phase and out-ofphase approaches are susceptible to noise in the sourcing
mode.
300kHz CLOCK
SOURCING
OUT-OF-PHASE
SOURCING
IN-PHASE
SINKING
FIGURE 9. CHANNEL INTERFERENCE VIN = 7.5V...24V
Noise immunity can be improved by operating the VTT
converter with a 90o phase shift. As the time diagrams in
Figure 10 show, the points of concern are always about a
quarter of the period away from the noise emitting
transitions.
300kHz CLOCK
Figure 12 shows the power supply that provides +2.5V and
+1.8V for memory and graphic interface chipset from +5.0V
system rail.
Figure 14 and 15 show application circuits of a complete
power solution for DDR memory that becomes a preferred
choice in modern computers. The power supply shown in
Figure 14 generates +2.5V VDDQ voltage from +5.0V to
+24V battery voltage. The +1.25V VTT termination voltage
tracks VDDQ/2 and is derived from +2.5V VDDQ. To
complete the DDR memory power requirements, the +1.25V
reference voltage is also provided. The PG2 pin serves as
an output for the reference voltage in this mode.
Figure 15 depicts the DDR solution in the case where the 5V
system rail is used as a primary voltage source.
For detailed information on the circuit, including a Bill-ofMaterials and circuit board description, see Application Note
AN9995. Also see Intersil’s web site (http://www.intersil.com)
for the latest information.
VDDQ
SOURCING
VTT
Figures 11 and 12 show application circuits of a dual channel
DC/DC converter for a notebook PC.
Figure 13 shows an application circuit for a single-output
split input power supply with current sharing for advanced
graphic card applications.
SINKING
VTT
ISL6225 DC-DC Converter Application
Circuits
The power supply in Figure 11 provides +2.5V and +1.8V for
memory and graphic interface chipset from +5.0V to +24V
battery voltage.
VDDQ
VTT
Several ways of synchronization are implemented into the
chip. When the DDR pin is connected to GND, the channels
operate 180o out-of-phase. In the DDR mode when the DDR
pin is connected to VCC, the channels operate either inphase when the VIN pin is connected to the input voltage
source, or with 90o phase shift if the VIN pin is connected to
GND.
OUT-OF-PHASE
SINKING
SOURCING
VTT
IN-PHASE
SINKING
SOURCING
VTT
90o PHASE SHIFT
SINKING
FIGURE 10. CHANNEL INTERFERENCE VIN = 5V
FN9049 Rev 7.00
December 28, 2004
Page 13 of 19
ISL6225
VIN
+5.0V TO +24V
VCC
CR1
BAT54
WT1
C1
1.0F
+ C2
10F
C6
0.15F
Q1
L1
10H
C7
0.15F
DDR
GND
VIN
+2.50V
3.0A
1
13
28
VCC
6
23
BOOT2
UGATE1
5
24
UGATE2
PHASE1
4
25
PHASE2
BOOT1
14
ISEN1
22
7
ISEN2
2.00K
C11
15nF
Q2
+ C8
330F
R5
10K
R9
100K
R7
100K
C3
10nF
+ C5
10F
Q3
L2
10H
+1.80V
2.0A
R2
2.00K
LGATE1
2
PGND1
3
ISL6225
27
LGATE2
26
PGND2
Q4
C9 +
330F
R4
10K
2/2 FDS6912A
2/2 FDS6912A
VPULLUP
+ C10
10F
1/2 FDS6912A
1/2 FDS6912A
R1
R3
17.8K
+5V
CR2
BAT54
WT1
VOUT1
9
20
VOUT2
VSEN1
10
19
VSEN2
OCSET1
11
18
OCSET2
SOFT1
12
17
SOFT2
21
EN2
EN1
8
15
PG1
16
C4
10nF
R8
100K
C12
15nF
R6
10K
PG2/REF
POWER GOOD CH1
ENABLE
POWER GOOD CH2
FIGURE 11. DUAL OUTPUT APPLICATION CIRCUIT FOR ONE-STEP CONVERSION
FN9049 Rev 7.00
December 28, 2004
Page 14 of 19
ISL6225
VCC
CR1
BAT54
WT1
C1
1.0F
+ C2
10F
C6
0.15F
GND
VIN
Q1
L1
4.7H
+2.50V
3.0A
1
14
13
28
VCC
BOOT1
6
23
BOOT2
UGATE1
5
24
UGATE2
PHASE1
4
25
PHASE2
C11
15nF
+ C8
ISEN1
PGND1
22
7
R5
10K
R9
100K
R7
100K
C3
10nF
+1.80V
2.0A
R2
ISEN2
ISL6225
2
3
27
LGATE2
26
PGND2
Q4
2/2 FDS6912A
VPULLUP
L2
4.7H
2.00K
LGATE1
330F
Q3
1/2 FDS6912A
2.00K
Q2
+ C5
10F
C7
0.15F
DDR
1/2 FDS6912A
R1
R3
17.8K
+5V
CR2
BAT54
WT1
C9 +
330F
R4
10K
2/2 FDS6912A
VOUT1
9
20
VOUT2
VSEN1
10
19
VSEN2
OCSET1
11
18
OCSET2
SOFT1
12
17
SOFT2
EN1
8
21
EN2
15
PG1
16
C4
10nF
R8
100K
C12
15nF
R6
10K
PG2/REF
POWER GOOD CH1
ENABLE
POWER GOOD CH2
FIGURE 12. DUAL OUTPUT APPLICATION CIRCUIT FOR TWO-STEP CONVERSION
FN9049 Rev 7.00
December 28, 2004
Page 15 of 19
ISL6225
VIN
+12V
CR1
BAT54
WT1
C1
1.0F
+ C2
10F
C6
0.15F
GND
VIN
Q1
L1
10H
13
1
28
VCC
6
23
BOOT2
UGATE1
5
24
UGATE2
PHASE1
4
25
PHASE2
BOOT1
14
Q3
L2
4.7H
1/2 FDS6912A
R1
ISEN1
22
7
R2
ISEN2
2.00K
2.00K
C12
15nF
Q2
+ C8
330F
LGATE1
2
PGND1
3
ISL6225
27
LGATE2
26
PGND2
Q4
2/2 FDS6912A
VOUT1
9
20
VOUT2
VSEN1
10
19
VSEN2
OCSET1
11
18
OCSET2
SOFT1
12
17
SOFT2
21
EN2
EN1
R9
100K
R7
100K
C9 +
330F
R4
6.65K
2/2 FDS6912A
VPULLUP
R5
10K
+ C5
10F
C7
0.15F
DDR
1/2 FDS6912A
R3
6.65K
VCC
+5V
CR2
BAT54
WT1
C3
10nF
8
15
16
C4
10nF
R8
100K
C13
15nF
R6
10K
PG2/REF
PG1
POWER GOOD CH1
ENABLE
POWER GOOD CH2
R10
R11
0.01
0.01
C10 +
330F
+ C11
330F
+1.50V
8.0A
FIGURE 13. SINGLE-OUTPUT SPLIT INPUT POWER SUPPLY
FN9049 Rev 7.00
December 28, 2004
Page 16 of 19
ISL6225
VIN
+5.0V to +24V
VCC
CR1
BAT54
WT1
+ C2
10F
C1
1.0F
C6
0.15F
GND
VIN
Q1
+2.50V
3.0A
L1
4.6H
C7
0.15F
DDR
1
13
28
VCC
6
23
BOOT2
UGATE1
5
24
UGATE2
PHASE1
4
25
PHASE2
BOOT1
14
R1
VDDQ
ISEN1
22
7
ISEN2
Q2
+ C8
330F
C12
15nF
LGATE1
2
PGND1
3
ISL6225
27
LGATE2
26
PGND2
R9
100K
R7
100K
C3
10nF
L2
1.5H
+1.25V
3.0A
R2
VTT
Q4
C9
330F
+
R4
10K
VOUT2
VOUT1
9
20
VSEN1
10
19
VSEN2
OCSET1
11
18
OCSET2
SOFT1
12
17
SOFT2
21
EN2
EN1
R5
10K
Q3
2/2 FDS6912A
2/2 FDS6912A
VPULLUP
+ C5
10F
1.00K
2.49K
R3
17.8K
+ C11
10F
1/2 FDS6912A
1/2 FDS6912A
~ 6.0A
+5V
CR2
BAT54
WT1
8
15
PG1
16
C10
10nF
R6
10K
PG2/REF
POWER GOOD CH1
ENABLE
VREF
C4
4.7F
FIGURE 14. APPLICATION CIRCUIT FOR COMPLETE DDR MEMORY POWER SOLUTION WITH ONE-STEP CONVERSION
FN9049 Rev 7.00
December 28, 2004
Page 17 of 19
ISL6225
VCC
CR1
BAT54
WT1
+ C2
10F
C1
1.0F
C6
0.15F
GND
VIN
Q1
+2.50V
3.0A
L1
4.6H
C7
0.15F
DDR
1
13
28
VCC
6
23
BOOT2
UGATE1
5
24
UGATE2
PHASE1
4
25
PHASE2
BOOT1
14
R1
VDDQ
ISEN1
22
7
ISEN2
2.49K
C12
15nF
Q2
+ C8
R3
17.8K
330F
LGATE1
2
PGND1
3
R9
100K
R7
100K
C3
10nF
10F
Q3
L2
1.5H
+1.25V
3.0A
R2
VTT
ISL6225
27
LGATE2
26
PGND2
Q4
C9 +
330F
R4
10K
2/2 FDS6912A
VOUT1
9
20
VOUT2
VSEN1
10
19
VSEN2
OCSET1
11
18
OCSET2
SOFT1
12
17
SOFT2
21
EN2
EN1
R5
10K
+ C11
1.00K
2/2 FDS6912A
VPULLUP
+ C10
10F
1/2 FDS6912A
1/2 FDS6912A
~ 6.0A
+5V
CR2
BAT54
WT1
8
15
PG1
16
C5
10nF
R6
10K
PG2/REF
POWER GOOD CH1
ENABLE
VREF
C4
4.7F
FIGURE 15. APPLICATION CIRCUIT FOR COMPLETE DDR MEMORY POWER SOLUTION WITH TWO-STEP CONVERSION
FN9049 Rev 7.00
December 28, 2004
Page 18 of 19
ISL6225
Shrink Small Outline Plastic Packages (SSOP)
Quarter Size Outline Plastic Packages (QSOP)
M28.15
N
INDEX
AREA
H
0.25(0.010) M
E
2
SYMBOL
3
0.25
0.010
SEATING PLANE
-A-
INCHES
GAUGE
PLANE
-B1
28 LEAD SHRINK SMALL OUTLINE PLASTIC PACKAGE
(0.150” WIDE BODY)
B M
A
D
h x 45°
-C-
e
0.17(0.007) M
A2
A1
B
L
C
0.10(0.004)
C A M
B S
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.
MIN
MAX
MILLIMETERS
MIN
MAX
NOTES
A
0.053
0.069
1.35
1.75
-
A1
0.004
0.010
0.10
0.25
-
A2
-
0.061
-
1.54
-
B
0.008
0.012
0.20
0.30
9
C
0.007
0.010
0.18
0.25
-
D
0.386
0.394
9.81
10.00
3
E
0.150
0.157
3.81
3.98
4
e
0.025 BSC
0.635 BSC
-
H
0.228
0.244
5.80
6.19
-
h
0.0099
0.0196
0.26
0.49
5
L
0.016
0.050
0.41
1.27
6
N
28
0°
28
8°
0°
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.
7
8°
Rev. 1 6/04
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. Dimension “B” does not include dambar protrusion. Allowable dambar protrusion shall be 0.10mm (0.004 inch) total in excess of “B”
dimension at maximum material condition.
10. Controlling dimension: INCHES. Converted millimeter dimensions
are not necessarily exact.
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modification does not, in Intersil's sole judgment, affect the form, fit or function of the product. Accordingly, the reader is cautioned to verify that datasheets are
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For information regarding Intersil Corporation and its products, see www.intersil.com
FN9049 Rev 7.00
December 28, 2004
Page 19 of 19