Renesas ISL6261IRZ Single-phase core regulator for imvp-6â® mobile cpus Datasheet

DATASHEET
ISL6261
FN9251
Rev 1.00
Sep 27, 2006
Single-Phase Core Regulator for IMVP-6® Mobile CPUs
The ISL6261 is a single-phase buck regulator implementing
lntel® IMVP-6® protocol, with embedded gate drivers.
Features
The heart of the ISL6261 is the patented R3 Technology™,
Intersil’s Robust Ripple Regulator modulator. Compared with
the traditional multi-phase buck regulator, the R3
Technology™ has faster transient response. This is due to
the R3 modulator commanding variable switching frequency
during a load transient.
• Internal gate driver with 2A driving capability
lntel® Mobile Voltage Positioning (IMVP) is a smart voltage
regulation technology effectively reducing power dissipation
in lntel® Pentium processors. To boost battery life, the
ISL6261 supports DPRSLRVR (deeper sleep) function and
maximizes the efficiency via automatically changing
operation modes. At heavy load in the active mode, the
regulator commands the continuous conduction mode
(CCM) operation. When the CPU enters deeper sleep mode,
the ISL6261 enables diode emulation to maximize the
efficiency at light load. Asserting the FDE pin of the ISL6261
in deeper sleep mode will further decrease the switching
frequency at light load and increase the regulator efficiency.
A 7-bit digital-to-analog converter (DAC) allows dynamic
adjustment of the core output voltage from 0.300V to 1.500V.
The ISL6261 has 0.5% system voltage accuracy over
temperature.
A unity-gain differential amplifier provides remote voltage
sensing at the CPU die. This allows the voltage on the CPU
die to be accurately measured and regulated per lntel®
IMVP-6 specification. Current sensing can be implemented
through either lossless inductor DCR sensing or precise
resistor sensing. If DCR sensing is used, an NTC thermistor
network will thermally compensates the gain and the time
constant variations caused by the inductor DCR change.
• Precision single-phase CORE voltage regulator
- 0.5% system accuracy over temperature
- Enhanced load line accuracy
• Microprocessor voltage identification input
- 7-Bit VID input
- 0.300V to 1.500V in 12.5mV steps
- Support VID change on-the-fly
• Multiple current sensing schemes supported
- Lossless inductor DCR current sensing
- Precision resistive current sensing
• Thermal monitor
• User programmable switching frequency
• Differential remote voltage sensing at CPU die
• Overvoltage, undervoltage, and overcurrent protection
• Pb-free plus anneal available (RoHS compliant)
Ordering Information
PART NUMBER
(NOTE)
PART
MARKING
TEMP
RANGE
(°C)
PACKAGE PKG.
(Pb-FREE) DWG. #
ISL6261CRZ
ISL6261CRZ
-10 to +100 40 Ld 6x6
QFN
L40.6x6
ISL6261CRZ-T
ISL6261CRZ
-10 to +100 40 Ld 6x6 L40.6x6
QFN, T&R
ISL6261CR7Z
ISL6261CR7Z -10 to +100 48 Ld 7x7
QFN
L48.7x7
ISL6261CR7Z-T ISL6261CR7Z -10 to +100 48 Ld 7x7 L48.7x7
QFN, T&R
ISL6261IRZ
ISL6261IRZ
-40 to +100 40 Ld 6x6
QFN
L40.6x6
ISL6261IRZ-T
ISL6261IRZ
-40 to +100 40 Ld 6x6 L40.6x6
QFN, T&R
ISL6261IR7Z
ISL6261IR7Z
-40 to +100 48 Ld 7x7
QFN
ISL6261IR7Z-T
ISL6261IR7Z
-40 to +100 48 Ld 7x7 L48.7x7
QFN, T&R
L48.7x7
NOTE: Intersil Pb-free plus anneal 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.
FN9251 Rev 1.00
Sep 27, 2006
Page 1 of 34
ISL6261
Pinouts
PGOOD
3V3
CLK_EN
DPRSTP#
DPRSLPVR
VR_ON
VID6
VID5
VID4
VID3
ISL6261
(40 LD QFN)
40
39
38
37
36
35
34
33
32
31
FDE
1
30 VID2
PGD_IN
2
29 VID1
RBIAS
3
28 VID0
VR_TT#
4
27 VCCP
NTC
5
SOFT
6
OCSET
7
24 PHASE
VW
8
23 UGATE
COMP
9
22 BOOT
FB
10
21 NC
26 LGATE
DROOP
17
18
19
20
VDD
RTN
16
VSS
VSEN
15
VIN
14
25 VSSP
VSUM
13
VO
12
DFB
11
VDIFF
GND PAD
(BOTTOM)
FN9251 Rev 1.00
Sep 27, 2006
3V3
CLK_EN#
DPRSTP#
DPRSLPVR
VR_ON
VID6
VID5
VID4
VID3
VID2
VID1
VID0
ISL6261
(48 LD QFN)
48
47
46
45
44
43
42
41
40
39
38
37
PGOOD
1
36 NC
FDE
2
35 NC
PGD_IN
3
34 NC
RBIAS
4
33 NC
VR_TT#
5
32 NC
NTC
6
SOFT
7
OCSET
8
29 VSSP
VW
9
28 PHASE
COMP 10
27 UGATE
31 VCCP
GND PAD
(BOTTOM)
30 LGATE
13
14
15
16
17
18
19
20
21
22
23
24
DROOP
DFB
VO
VSUM
VIN
VSS
VDD
NC
NC
25 NC
RTN
NC 12
VSEN
26 BOOT
VDIFF
FB 11
Page 2 of 34
ISL6261
Absolute Maximum Ratings
Thermal Information
Supply Voltage, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +7V
Battery Voltage, VIN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+28V
Boot Voltage (BOOT) . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +33V
Boot to Phase Voltage (BOOT-PHASE). . . . . . . . . -0.3V to +7V(DC)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to +9V(<10ns)
Phase Voltage (PHASE) . . . . . . . . . -7V (<20ns Pulse Width, 10µJ)
UGATE Voltage (UGATE) . . . . . . . . . . PHASE-0.3V (DC) to BOOT
. . . . . . . . . . . . . .PHASE-5V (<20ns Pulse Width, 10µJ) to BOOT
LGATE Voltage (LGATE) . . . . . . . . . . . . . . -0.3V (DC) to VDD+0.3V
. . . . . . . . . . . . . . . . -2.5V (<20ns Pulse Width, 5µJ) to VDD+0.3V
All Other Pins . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to (VDD +0.3V)
Open Drain Outputs, PGOOD, VR_TT# . . . . . . . . . . . . -0.3 to +7V
HBM ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .>3kV
Thermal Resistance (Typical)
JA (°C/W)
JC (°C/W)
6x6 QFN Package (Notes 1, 2) . . . . . . 33
5.5
7x7 QFN Package (Notes 1, 2) . . . . . . 30
5.5
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . .-65°C to +150°C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . +300°C
Recommended Operating Conditions
Supply Voltage, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+5V ±5%
Battery Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . +5V to 21V
Ambient Temperature . . . . . . . . . . . . . . . . . . . . . . .-10°C to +100°C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . .-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.
NOTE:
1. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief TB379.
2. For JC, the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
PARAMETER
VDD = 5V, TA = -10°C to +100°C, Unless Otherwise Specified.
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
VR_ON = 3.3V
-
3.1
3.6
mA
VR_ON = 0V
-
-
1
µA
INPUT POWER SUPPLY
+5V Supply Current
IVDD
+3.3V Supply Current
I3V3
No load on CLK_EN# pin
-
-
1
µA
Battery Supply Current at VIN pin
IVIN
VR_ON = 0, VIN = 25V
-
-
1
µA
POR (Power-On Reset) Threshold
PORr
VDD Rising
-
4.35
4.5
V
PORf
VDD Falling
3.85
4.1
-
V
No load, close loop, active mode,
TA = 0°C to +100°C,
VID = 0.75-1.5V
-0.5
-
0.5
%
VID = 0.5-0.7375V
-8
-
8
mV
VID = 0.3-0.4875V
-15
-
15
mV
RRBIAS = 147k
1.45
1.47
1.49
V
1.188
1.2
1.212
V
SYSTEM AND REFERENCES
System Accuracy
%Error
(Vcc_core)
RBIAS Voltage
RRBIAS
Boot Voltage
VBOOT
Maximum Output Voltage
VCC_CORE
(max)
VID = [0000000]
-
1.5
-
V
Minimum Output Voltage
VCC_CORE
(min)
VID = [1100000]
-
0.3
-
V
VID = [1111111]
-
0.0
-
V
RFSET = 7k,
Vcomp = 2V
-
333
-
kHz
200
-
500
kHz
0.3
mV
-
dB
VID Off State
CHANNEL FREQUENCY
Nominal Channel Frequency
fSW
Adjustment Range
AMPLIFIERS
Droop Amplifier Offset
Error Amp DC Gain (Note 3)
FN9251 Rev 1.00
Sep 27, 2006
-0.3
AV0
-
90
Page 3 of 34
ISL6261
Electrical Specifications
VDD = 5V, TA = -10°C to +100°C, Unless Otherwise Specified. (Continued)
PARAMETER
SYMBOL
Error Amp Gain-Bandwidth Product
(Note 3)
GBW
MIN
TYP
MAX
UNITS
CL = 20pF
-
18
-
MHz
SR
CL = 20pF
-
5.0
-
V/µs
IIN(FB)
-
10
150
nA
Soft-start Current
ISS
-46
-41
-36
µA
Soft Geyserville Current
IGV
|SOFT - REF|>100mV
±175
±200
±225
µA
Soft Deeper Sleep Entry Current
IC4
DPRSLPVR = 3.3V
-46
-41
-36
µA
Soft Deeper Sleep Exit Current
IC4EA
DPRSLPVR = 3.3V
36
41
46
µA
Soft Deeper Sleep Exit Current
IC4EB
DPRSLPVR = 0V
175
200
225
µA
Error Amp Slew Rate (Note 3)
FB Input Current
TEST CONDITIONS
SOFT-START CURRENT
GATE DRIVER DRIVING CAPABILITY (Note 4)
UGATE Source Resistance
RSRC(UGATE)
500mA Source Current
-
1
1.5

UGATE Source Current
ISRC(UGATE)
VUGATE_PHASE = 2.5V
-
2
-
A
UGATE Sink Resistance
RSNK(UGATE)
500mA Sink Current
-
1
1.5

UGATE Sink Current
ISNK(UGATE)
VUGATE_PHASE = 2.5V
-
2
-
A
LGATE Source Resistance
RSRC(LGATE)
500mA Source Current
-
1
1.5

LGATE Source Current
ISRC(LGATE)
VLGATE = 2.5V
-
2
-
A
LGATE Sink Resistance
RSNK(LGATE)
500mA Sink Current
-
0.5
0.9

LGATE Sink Current
ISNK(LGATE)
VLGATE = 2.5V
-
4
-
A
UGATE to PHASE Resistance
RP(UGATE)
-
1.1
-
k
GATE DRIVER SWITCHING TIMING (Refer to Timing Diagram)
UGATE Turn-on Propagation Delay
tPDHU
PVCC = 5V, Output Unloaded
20
30
44
ns
LGATE Turn-on Propagation Delay
tPDHL
PVCC = 5V, Output Unloaded
7
15
30
ns
0.43
0.58
0.67
V
BOOTSTRAP DIODE
Forward Voltage
VDDP = 5V, Forward Bias Current = 2mA
Leakage
VR = 16V
-
-
1
A
POWER GOOD and PROTECTION MONITOR
PGOOD Low Voltage
VOL
IPGOOD = 4mA
-
0.11
0.4
V
PGOOD Leakage Current
IOH
PGOOD = 3.3V
-1
-
1
µA
PGOOD Delay
tpgd
CLK_EN# Low to PGOOD High
5.5
6.8
8.1
ms
Overvoltage Threshold
OVH
VO rising above setpoint >1ms
160
200
240
mV
Severe Overvoltage Threshold
OVHS
VO rising above setpoint >0.5µs
1.675
1.7
1.725
V
10
10.2
µA
3.5
mV
OCSET Reference Current
I(Rbias) = 10µA
9.8
OC Threshold Offset
DROOP rising above OCSET >120µs
-3.5
VO below set point for >1ms
-360
-300
-240
mV
Undervoltage Threshold
(VDIFF-SOFT)
UVf
LOGIC THRESHOLDS
VR_ON, DPRSLPVR and PGD_IN
Input Low
VIL(3.3V)
-
-
1
V
VR_ON, DPRSLPVR and PGD_IN
Input High
VIH(3.3V)
2.3
-
-
V
FN9251 Rev 1.00
Sep 27, 2006
Page 4 of 34
ISL6261
Electrical Specifications
VDD = 5V, TA = -10°C to +100°C, Unless Otherwise Specified. (Continued)
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
IIL
Logic input is low
-1
0
-
A
IIH
Logic input is high
-
0
1
A
IIL_DPRSLP
DPRSLPVR logic input is low
-1
0
-
A
IIH_DPRSLP
DPRSLPVR logic input is high
-
0.45
1
A
Leakage Current on VR_ON and
PGD_IN
Leakage Current on DPRSLPVR
TEST CONDITIONS
DAC(VID0-VID6), PSI# and
DPRSTP# Input Low
VIL(1.0V)
-
-
0.3
V
DAC(VID0-VID6), PSI# and
DPRSTP# Input High
VIH(1.0V)
0.7
-
-
V
Leakage Current of DAC(VID0VID6) and DPRSTP#
IIL
DPRSLPVR logic input is low
-1
0
-
A
IIH
DPRSLPVR logic input is high
-
0.45
1
A
53
60
67
µA
1.17
1.2
1.25
V
-
5
9
2.9
3.1
-
V
-
0.18
0.4
V
THERMAL MONITOR
NTC Source Current
NTC = 1.3V
Over-temperature Threshold
V(NTC) falling
VR_TT# Low Output Resistance
RTT
I = 20mA
CLK_EN# High Output Voltage
VOH
3V3 = 3.3V, I = -4mA
CLK_EN# Low Output Voltage
VOL
ICLK_EN# = 4mA
CLK_EN# OUTPUT LEVELS
NOTES:
3. Guaranteed by characterization.
4. Guaranteed by design.
Gate Driver Timing Diagram
PWM
tPDHU
tFU
tRU
1V
UGATE
1V
LGATE
tFL
FN9251 Rev 1.00
Sep 27, 2006
tRL
tPDHL
Page 5 of 34
ISL6261
PGOOD
3V3
CLK_EN
DPRSTP#
DPRSLPVR
VR_ON
VID6
VID5
VID4
VID3
Functional Pin Description
40
39
38
37
36
35
34
33
32
31
FDE
1
30 VID2
PGD_IN
2
29 VID1
RBIAS
3
28 VID0
VR_TT#
4
27 VCCP
NTC
5
SOFT
6
OCSET
7
24 PHASE
VW
8
23 UGATE
COMP
9
22 BOOT
FB
10
21 NC
26 LGATE
GND PAD
(BOTTOM)
11
12
13
14
15
16
17
18
19
20
VDIFF
VSEN
RTN
DROOP
DFB
VO
VSUM
VIN
VSS
VDD
25 VSSP
FDE
VW
Forced diode emulation enable signal. Logic high of FDE with
logic low of DPRSTP# forces the ISL6261 to operate in diode
emulation mode with an increased VW-COMP voltage window.
A resistor from this pin to COMP programs the switching
frequency (eg. 6.81K = 300kHz).
PGD_IN
The output of the error amplifier.
Digital Input. Suggest connecting to MCH_PWRGD, which
indicates that VCC_MCH voltage is within regulation.
FB
RBIAS
A 147K resistor to VSS sets internal current reference.
VR_TT#
COMP
The inverting input of the error amplifier.
VDIFF
The output of the differential amplifier.
Thermal overload output indicator with open-drain output.
Over-temperature pull-down resistance is 10.
VSEN
NTC
RTN
Thermistor input to VR_TT# circuit and a 60µA current source
is connected internally to this pin.
Remote core voltage sense return.
SOFT
The output of the droop amplifier. DROOP-VO voltage is the
droop voltage.
A capacitor from this pin to GND pin sets the maximum slew
rate of the output voltage. The SOFT pin is the non-inverting
input of the error amplifier.
OCSET
Overcurrent set input. A resistor from this pin to VO sets
DROOP voltage limit for OC trip. A 10µA current source is
connected internally to this pin.
FN9251 Rev 1.00
Sep 27, 2006
Remote core voltage sense input.
DROOP
DFB
The inverting input of the droop amplifier.
VO
An input to the IC that reports the local output voltage.
Page 6 of 34
ISL6261
VSUM
NC
This pin is connected to one terminal of the capacitor in the
current sensing R-C network.
Not connected. Ground this pin in the practical layout.
VIN
VID input with VID0 as the least significant bit (LSB) and VID6
as the most significant bit (MSB).
Power stage input voltage. It is used for input voltage feed
forward to improve the input line transient performance.
VSS
VID0, VID1, VID2, VID3, VID4, VID5, VID6
VR_ON
Signal ground. Connect to controller local ground.
VR enable pin. A logic high signal on this pin enables the
regulator.
VDD
DPRSLPVR
5V control power supply.
Deeper sleep enable signal. A logic high indicates that the
microprocessor is in Deeper Sleep Mode and also indicates a
slow Vo slew rate with 41A discharging or charging the SOFT
cap.
BOOT
Upper gate driver supply voltage. An internal bootstrap diode is
connected to the VCCP pin.
UGATE
DPRSTP#
The upper-side MOSFET gate signal.
Deeper sleep slow wake up signal. A logic low signal on this
pin indicates that the microprocessor is in Deeper Sleep Mode.
PHASE
CLK_EN#
The phase node. This pin should connect to the source of
upper MOSFET.
Digital output for system PLL clock. Goes active 20µs after
PGD_IN is active and Vcore is within 10% of boot voltage.
VSSP
3V3
The return path of the lower gate driver.
3.3V supply voltage for CLK_EN#.
LGATE
PGOOD
The lower-side MOSFET gate signal.
Power good open-drain output. Needs to be pulled up
externally by a 680 resistor to VCCP or 1.9k to 3.3V.
VCCP
5V power supply for the gate driver.
FN9251 Rev 1.00
Sep 27, 2006
Page 7 of 34
FN9251 Rev 1.00
Sep 27, 2006
DROOP
DFB
VSUM
OCSET
VID6
VID5
VID4
VID3
VID2
VID1
VID0
DAC
VO VSEN RTN
VO
10uA
VR_ON
DROOP
RBIAS
DPRSLPVR DPRSTP#
1
1
VO
SOFT
VDIFF SOFT FB
OC
MODE CONTROL
FDE
CLK_EN#
PGOOD
3V3
PGOOD
E/A
COMP
VIN VSOFT
VW
VW
MODULATOR
OC
FAULT AND PGOOD LOGIC
FLT
FLT
60uA
VIN
VIN
DRIVER
LOGIC
VCCP
1.22V
GND
VSS
PGOOD MONITOR AND LOGIC
PGD_IN
VCCP
VDD
VCCP
VCCP
VSSP
LGATE
PHASE
UGATE
BOOT
VR_TT#
NTC
ISL6261
Function Block Diagram
FIGURE 1. SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM OF ISL6261
Page 8 of 34
ISL6261
Simplified Application Circuit for DCR Current Sensing
V+5
V+3.3
Vin
R4
C4
R5
R6
C5
3V3
VDD VCCP
RBIAS
VIN
C8
NTC
UGATE
SOFT
BOOT
Lo
C6
VR_TT#
VR_TT#
PHASE
Vo
VIDs
VID<0:6>
Co
DPRSTP#
DPRSTP#
DPRSLPVR
DPRSLPVR
LGATE
FDE
PGD_IN
MCH_PWRGD
VSSP
CLK_EN#
CLK_ENABLE#
VR_ON
VR_ON
IMVP6_PWRGD
PGOOD
VCC-SENSE
VSEN
VSS-SENSE
RTN
R7
C7
C3
C9
C2
R3
C1
ISL6261
OCSET
R10
R11
C10
R12
FB
VDIFF
NTC
Network
DFB
COMP
R1
R9
VO
VW
R2
R8
VSUM
DROOP
VSS
FIGURE 2. ISL6261-BASED IMVP-6® SOLUTION WITH INDUCTOR DCR CURRENT SENSING
FN9251 Rev 1.00
Sep 27, 2006
Page 9 of 34
ISL6261
Simplified Application Circuit for Resistive Current Sensing
V+5
V+3.3
Vin
R4
C4
R5
R6
C5
3V3
VDD VCCP
RBIAS
VIN
C8
NTC
UGATE
SOFT
BOOT
Lo
C6
VR_TT#
VR_TT#
PHASE
R sen
VIDs
VID<0:6>
Co
DPRSTP#
DPRSTP#
Vo
DPRSLPVR
DPRSLPVR
LGATE
FDE
PGD_IN
MCH_PWRGD
VSSP
CLK_EN#
CLK_ENABLE#
VR_ON
VR_ON
IMVP6_PWRGD
PGOOD
VCC-SENSE
C9
VSEN
VSS-SENSE
R7
C7
C3
RTN
VO
ISL6261
VW
R2
C2
R3
C1
OCSET
R11
C10
R12
FB
VDIFF
R10
DFB
COMP
R1
R8
VSUM
DROOP
VSS
FIGURE 3. ISL6261-BASED IMVP-6® SOLUTION WITH RESISTIVE CURRENT SENSING
FN9251 Rev 1.00
Sep 27, 2006
Page 10 of 34
ISL6261
Theory of Operation
The ISL6261 is a single-phase regulator implementing Intel®
IMVP-6® protocol and includes an integrated gate driver for
reduced system cost and board area. The ISL6261 IMVP-6®
solution provides optimum steady state and transient
performance for microprocessor core voltage regulation
applications up to 25A. Implementation of diode emulation
mode (DEM) operation further enhances system efficiency.
The heart of the ISL6261 is the patented R3 Technology™,
Intersil’s Robust Ripple Regulator modulator. The R3™
modulator combines the best features of fixed frequency and
hysteretic PWM controllers while eliminating many of their
shortcomings. The ISL6261 modulator internally synthesizes
an analog of the inductor ripple current and uses hysteretic
comparators on those signals to establish PWM pulses.
Operating on the large-amplitude and noise-free synthesized
signals allows the ISL6261 to achieve lower output ripple and
lower phase jitter than either conventional hysteretic or fixed
frequency PWM controllers. Unlike conventional hysteretic
converters, the ISL6261 has an error amplifier that allows the
controller to maintain 0.5% voltage regulation accuracy
throughout the VID range from 0.75V to 1.5V.
The hysteretic window voltage is with respect to the error
amplifier output. Therefore the load current transient results in
increased switching frequency, which gives the R3™ regulator
a faster response than conventional fixed frequency PWM
regulators.
Start-up Timing
With the controller’s VDD pin voltage above the POR
threshold, the start-up sequence begins when VR_ON
exceeds the 3.3V logic HIGH threshold. In approximately
100s, SOFT and VO start ramping to the boot voltage of 1.2V.
At startup, the regulator always operates in continuous current
mode (CCM), regardless of the control signals. During this
interval, the SOFT cap is charged by a 41A current source. If
the SOFT capacitor is 20nF, the SOFT ramp will be 2mV/s for
a soft-start time of 600s. Once VO is within 10% of the boot
voltage and PGD_IN is HIGH for six PWM cycles (20µs for
300kHz switching frequency), CLK_EN# is pulled LOW, and
the SOFT cap is charged/discharged by approximate 200µA
and VO slews at 10mV/s to the voltage set by the VID pins. In
approximately 7ms, PGOOD is asserted HIGH. Figure 4 shows
typical startup timing.
PGD_IN Latch
It should be noted that PGD_IN going low will cause the
converter to latch off. Toggling PGD_IN won’t clear the latch.
Toggling VR_ON will clear it. This feature allows the converter
to respond to other system voltage outages immediately.
FN9251 Rev 1.00
Sep 27, 2006
VDD
VR_ON
100us
SOFT &VO
10mV/us
2mV/us Vboot
~20us
PGD_IN
CLK_EN#
~7ms
IMVP-VI PGOOD
FIGURE 4. SOFT-START WAVEFORMS USING A 20nF SOFT
CAPACITOR
Static Operation
After the startup sequence, the output voltage will be regulated
to the value set by the VID inputs per Table 1, which is
presented in the lntel® IMVP-6® specification. The ISL6261
regulates the output voltage with ±0.5% accuracy over the
range of 0.7V to 1.5V.
A true differential amplifier remotely senses the core voltage to
precisely control the voltage at the microprocessor die. VSEN
and RTN pins are the inputs to the differential amplifier.
As the load current increases from zero, the output voltage
droops from the VID value proportionally to achieve the IMVP6® load line. The ISL6261 can sense the inductor current
through the intrinsic series resistance of the inductors, as
shown in Figure 2, or through a precise resistor in series with
the inductor, as shown in Figure 3. The inductor current
information is fed to the VSUM pin, which is the non-inverting
input to the droop amplifier. The DROOP pin is the output of
the droop amplifier, and DROOP-VO voltage is a highbandwidth analog representation of the inductor current. This
voltage is used as an input to a differential amplifier to achieve
the IMVP-6® load line, and also as the input to the overcurrent
protection circuit.
When using inductor DCR current sensing, an NTC thermistor
is used to compensate the positive temperature coefficient of
the copper winding resistance to maintain the load-line
accuracy.
The switching frequency of the ISL6261 controller is set by the
resistor RFSET between pins VW and COMP, as shown in
Figures 2 and 3.
Page 11 of 34
ISL6261
TABLE 1. VID TABLE FROM INTEL IMVP-6 SPECIFICATION
TABLE 1. VID TABLE FROM INTEL IMVP-6 SPECIFICATION
(Continued)
VID6
VID5
VID4
VID3
VID2
VID1
VID0
Vo (V)
VID6
VID5
VID4
VID3
VID2
VID1
VID0
Vo (V)
0
0
0
0
0
0
0
1.5000
0
1
0
1
0
1
0
0.9750
1
0
1
0
1
1
0.9625
0
0
0
0
0
0
1
1.4875
0
0
0
0
0
0
1
0
1.4750
0
1
0
1
1
0
0
0.9500
0
0
0
0
0
1
1
1.4625
0
1
0
1
1
0
1
0.9375
0
0
0
0
1
0
0
1.4500
0
1
0
1
1
1
0
0.9250
1
0
1
1
1
1
0.9125
0
0
0
0
1
0
1
1.4375
0
0
0
0
0
1
1
0
1.4250
0
1
1
0
0
0
0
0.9000
0
0
0
0
1
1
1
1.4125
0
1
1
0
0
0
1
0.8875
0
0
0
1
0
0
0
1.4000
0
1
1
0
0
1
0
0.8750
1
1
0
0
1
1
0.8625
0
0
0
1
0
0
1
1.3875
0
0
0
0
1
0
1
0
1.3750
0
1
1
0
1
0
0
0.8500
0
0
0
1
0
1
1
1.3625
0
1
1
0
1
0
1
0.8375
0
0
0
1
1
0
0
1.3500
0
1
1
0
1
1
0
0.8250
1
1
0
1
1
1
0.8125
0
0
0
1
1
0
1
1.3375
0
0
0
0
1
1
1
0
1.3250
0
1
1
1
0
0
0
0.8000
0
0
0
1
1
1
1
1.3125
0
1
1
1
0
0
1
0.7875
0
0
1
0
0
0
0
1.3000
0
1
1
1
0
1
0
0.7750
1
1
1
0
1
1
0.7625
0
0
1
0
0
0
1
1.2875
0
0
0
1
0
0
1
0
1.2750
0
1
1
1
1
0
0
0.7500
0
0
1
0
0
1
1
1.2625
0
1
1
1
1
0
1
0.7375
0
0
1
0
1
0
0
1.2500
0
1
1
1
1
1
0
0.7250
1
1
1
1
1
1
0.7125
0
0
1
0
1
0
1
1.2375
0
0
0
1
0
1
1
0
1.2250
1
0
0
0
0
0
0
0.7000
0
0
1
0
1
1
1
1.2125
1
0
0
0
0
0
1
0.6875
0
0
1
1
0
0
0
1.2000
1
0
0
0
0
1
0
0.6750
0
0
0
0
1
1
0.6625
0
0
1
1
0
0
1
1.1875
1
0
0
1
1
0
1
0
1.1750
1
0
0
0
1
0
0
0.6500
0
0
1
1
0
1
1
1.1625
1
0
0
0
1
0
1
0.6375
0
0
1
1
1
0
0
1.1500
1
0
0
0
1
1
0
0.6250
0
0
0
1
1
1
0.6125
0
0
1
1
1
0
1
1.1375
1
0
0
1
1
1
1
0
1.1250
1
0
0
1
0
0
0
0.6000
0
0
1
1
1
1
1
1.1125
1
0
0
1
0
0
1
0.5875
0
1
0
0
0
0
0
1.1000
1
0
0
1
0
1
0
0.5750
0
0
1
0
1
1
0.5625
0
1
0
0
0
0
1
1.0875
1
0
1
0
0
0
1
0
1.0750
1
0
0
1
1
0
0
0.5500
0
1
0
0
0
1
1
1.0625
1
0
0
1
1
0
1
0.5375
0
1
0
0
1
0
0
1.0500
1
0
0
1
1
1
0
0.5250
0
0
1
1
1
1
0.5125
0
1
0
0
1
0
1
1.0375
1
0
1
0
0
1
1
0
1.0250
1
0
1
0
0
0
0
0.5000
0
1
0
0
1
1
1
1.0125
1
0
1
0
0
0
1
0.4875
0
1
0
1
0
0
0
1.0000
1
0
1
0
0
1
0
0.4750
0.9875
1
0
1
0
0
1
1
0.4625
0
1
0
FN9251 Rev 1.00
Sep 27, 2006
1
0
0
1
Page 12 of 34
ISL6261
TABLE 1. VID TABLE FROM INTEL IMVP-6 SPECIFICATION
(Continued)
TABLE 1. VID TABLE FROM INTEL IMVP-6 SPECIFICATION
(Continued)
VID6
VID5
VID4
VID3
VID2
VID1
VID0
Vo (V)
VID6
VID5
VID4
VID3
VID2
VID1
VID0
Vo (V)
1
0
1
0
1
0
0
0.4500
1
1
0
1
0
1
1
0.1625
1
0
1
0
1
0
1
0.4375
1
1
0
1
1
0
0
0.1500
1
0
1
0
1
1
0
0.4250
1
1
0
1
1
0
1
0.1375
1
0
1
0
1
1
1
0.4125
1
1
0
1
1
1
0
0.1250
1
0
1
1
0
0
0
0.4000
1
1
0
1
1
1
1
0.1125
1
0
1
1
0
0
1
0.3875
1
1
1
0
0
0
0
0.1000
1
0
1
1
0
1
0
0.3750
1
1
1
0
0
0
1
0.0875
1
0
1
1
0
1
1
0.3625
1
1
1
0
0
1
0
0.0750
1
0
1
1
1
0
0
0.3500
1
1
1
0
0
1
1
0.0625
1
0
1
1
1
0
1
0.3375
1
1
1
0
1
0
0
0.0500
1
0
1
1
1
1
0
0.3250
1
1
1
0
1
0
1
0.0375
1
0
1
1
1
1
1
0.3125
1
1
1
0
1
1
0
0.0250
1
1
0
0
0
0
0
0.3000
1
1
1
0
1
1
1
0.0125
1
1
0
0
0
0
1
0.2875
1
1
1
1
0
0
0
0.0000
1
1
0
0
0
1
0
0.2750
1
1
1
1
0
0
1
0.0000
1
1
0
0
0
1
1
0.2625
1
1
1
1
0
1
0
0.0000
1
1
0
0
1
0
0
0.2500
1
1
1
1
0
1
1
0.0000
1
1
0
0
1
0
1
0.2375
1
1
1
1
1
0
0
0.0000
1
1
0
0
1
1
0
0.2250
1
1
1
1
1
0
1
0.0000
1
1
0
0
1
1
1
0.2125
1
1
1
1
1
1
0
0.0000
1
1
0
1
0
0
0
0.2000
1
1
1
1
1
1
1
0.0000
1
1
0
1
0
0
1
0.1875
1
1
0
1
0
1
0
0.1750
TABLE 2. CONTROL SIGNAL TRUTH TABLES FOR OPERATIONAL MODES OF ISL6261
FDE
DPRSLPVR
0
0
0
Forced CCM
0%
0
0
1
Diode Emulation Mode
0%
0
1
x
Enhanced Diode Emulation Mode
33%
1
x
x
Forced CCM
0%
Control
Signal
Logic
FN9251 Rev 1.00
Sep 27, 2006
OPERATIONAL MODE
VW-COMP WINDOW
VOLTAGE INCREASE
DPRSTP#
Page 13 of 34
ISL6261
High Efficiency Operation Mode
The operational modes of the ISL6261 depend on the control
signal states of DPRSTP#, FDE, and DPRSLPVR, as shown in
Table 2. These control signals can be tied to lntel® IMVP-6®
control signals to maintain the optimal system configuration for
all IMVP-6® conditions.
DPRSTP# = 0, FDE = 0 and DPRSLPVR = 1 enables the
ISL6261 to operate in diode emulation mode (DEM) by
monitoring the low-side FET current. In diode emulation mode,
when the low-side FET current flows from source to drain, it
turns on as a synchronous FET to reduce the conduction loss.
When the current reverses its direction trying to flow from drain
to source, the ISL6261 turns off the low-side FET to prevent
the output capacitor from discharging through the inductor,
therefore eliminating the extra conduction loss. When DEM is
enabled, the regulator works in automatic discontinuous
conduction mode (DCM), meaning that the regulator operates
in CCM in heavy load, and operates in DCM in light load. DCM
in light load decreases the switching frequency to increase
efficiency. This mode can be used to support the deeper sleep
mode of the microprocessor.
DPRSTP# = 0 and FDE = 1 enables the enhanced diode
emulation mode (EDEM), which increases the VW-COMP
window voltage by 33%. This further decreases the switching
frequency at light load to boost efficiency in the deeper sleep
mode.
For other combinations of DPRSTP#, FDE, and DPRSLPVR,
the ISL6261 operates in forced CCM.
The ISL6261 operational modes can be set according to CPU
mode signals to achieve the best performance. There are two
options: (1) Tie FDE to DPRSLPVR, and tie DPRSTP# and
DPRSLPVR to the corresponding CPU mode signals. This
configuration enables EDEM in deeper sleep mode to increase
efficiency. (2) Tie FDE to “1” and DPRSTP# to “0” permanently,
and tie DPRSLPVR to the corresponding CPU mode signal.
This configuration sets the regulator in EDEM all the time. The
regulator will enter DCM based on load current. Light-load
efficiency is increased in both active mode and deeper sleep
mode.
CPU mode-transition sequences often occur in concert with
VID changes. The ISL6261 employs carefully designed modetransition timing to work in concert with the VID changes.
The ISL6261 is equipped with internal counters to prevent
control signal glitches from triggering unintended mode
transitions. For example: Control signals lasting less than
seven switching periods will not enable the diode emulation
mode.
Dynamic Operation
The ISL6261 responds to VID changes by slewing to new
voltages with a dv/dt set by the SOFT capacitor and the logic of
DPRSLPVR. If CSOFT = 20nF and DPRSLPVR = 0, the output
voltage will move at a maximum dv/dt of ±10mV/s for large
changes. The maximum dv/dt can be used to achieve fast
recovery from Deeper Sleep to Active mode. If CSOFT = 20nF
and DPRSLPVR = 1, the output voltage will move at a dv/dt of
±2mV/s for large changes. The slow dv/dt into and out of
deeper sleep mode will minimize the audible noise. As the
output voltage approaches the VID command value, the dv/dt
moderates to prevent overshoot. The ISL6261 is IMVP-6®
compliant for DPRSTP# and DPRSLPVR logic.
Intersil R3™ has an intrinsic voltage feed forward function.
High-speed input voltage transients have little effect on the
output voltage.
Intersil R3™ commands variable switching frequency during
transients to achieve fast response. Upon load application, the
ISL6261 will transiently increase the switching frequency to
deliver energy to the output more quickly. Compared with
steady state operation, the PWM pulses during load
application are generated earlier, which effectively increases
the duty cycle and the response speed of the regulator. Upon
load release, the ILS6261 will transiently decrease the
switching frequency to effectively reduce the duty cycle to
achieve fast response.
TABLE 3. FAULT-PROTECTION SUMMARY OF ISL6261
FAULT TYPE
FAULT DURATION PRIOR
TO PROTECTION
PROTECTION ACTIONS
FAULT RESET
Overcurrent fault
120s
PWM tri-state, PGOOD latched low
VR_ON toggle or VDD toggle
Way-Overcurrent fault
< 2s
PWM tri-state, PGOOD latched low
VR_ON toggle or VDD toggle
Overvoltage fault (1.7V)
Immediately
Low-side FET on until Vcore < 0.85V, then PWM tristate, PGOOD latched low (OV-1.7V always)
VDD toggle
Overvoltage fault
(+200mV)
1ms
PWM tri-state, PGOOD latched low
VR_ON toggle or VDD toggle
Undervoltage fault
(-300mV)
1ms
PWM tri-state, PGOOD latched low
VR_ON toggle or VDD toggle
Over-temperature fault
(NTC<1.18)
Immediately
VR_TT# goes high
N/A
FN9251 Rev 1.00
Sep 27, 2006
Page 14 of 34
ISL6261
Protection
The ISL6261 provides overcurrent (OC), overvoltage (OV),
undervoltage (UV) and over-temperature (OT) protections as
shown in Table 3.
Overcurrent is detected through the droop voltage, which is
designed as described in the “Component Selection and
Application” section. The OCSET resistor sets the overcurrent
protection level. An overcurrent fault will be declared when the
droop voltage exceeds the overcurrent set point for more than
120µs. A way-overcurrent fault will be declared in less than
2µs when the droop voltage exceeds twice the overcurrent set
point. In both cases, the UGATE and LGATE outputs will be tristated and PGOOD will go low.
The over-current condition is detected through the droop
voltage. The droop voltage is equal to IcoreRdroop, where
Rdroop is the load line slope. A 10A current source flows out of
the OCSET pin and creates a voltage drop across ROCSET
(shown as R10 in Figure 2). Overcurrent is detected when the
droop voltage exceeds the voltage across ROCSET. Equation 1
gives the selection of ROCSET.
ROCSET 
I OC  Rdroop
10 A
(EQ. 1)
For example: The desired over current trip level, Ioc, is 30A,
Rdroop is 2.1m, Equation 1 gives ROCSET = 6.3k.
Undervoltage protection is independent of the overcurrent limit.
A UV fault is declared when the output voltage is lower than
(VID-300mV) for more than 1ms. The gate driver outputs will
be tri-stated and PGOOD will go low. Note that a practical core
regulator design usually trips OC before it trips UV.
There are two levels of overvoltage protection and response.
An OV fault is declared when the output voltage exceeds the
VID by +200mV for more than 1ms. The gate driver outputs will
be tri-stated and PGOOD will go low. The inductor current will
decay through the low-side FET body diode. Toggling of
VR_ON or bringing VDD below 4V will reset the fault latch. A
way-overvoltage (WOV) fault is declared immediately when the
output voltage exceeds 1.7V. The ISL6261 will latch PGOOD
low and turn on the low-side FETs. The low-side FETs will
remain on until the output voltage drops below approximately
0.85V, then all the FETs are turned off. If the output voltage
again rises above 1.7V, the protection process repeats. This
mechanism provides maximum protection against a shorted
high-side FET while preventing the output from ringing below
ground. Toggling VR_ON cannot reset the WOV protection;
recycling VDD will reset it. The WOV detector is active all the
time, even when other faults are declared, so the processor is
still protected against the high-side FET leakage while the
FETs are commanded off.
throttling to the system oversight processor. No other action is
taken within the ISL6261.
Component Selection and Application
Soft-Start and Mode Change Slew Rates
The ISL6261 commands two different output voltage slew rates
for various modes of operation. The slow slew rate reduces the
inrush current during startup and the audible noise during the
entry and the exit of Deeper Sleep Mode. The fast slew rate
enhances the system performance by achieving active mode
regulation quickly during the exit of Deeper Sleep Mode. The
SOFT current is bidirectional  charging the SOFT capacitor
when the output voltage is commanded to rise, and
discharging the SOFT capacitor when the output voltage is
commanded to fall.
Figure 5 shows the circuitry on the SOFT pin. The SOFT pin,
the non-inverting input of the error amplifier, is connected to
ground through capacitor CSOFT. ISS is an internal current
source connected to the SOFT pin to charge or discharge
CSOFT. The ISL6261 controls the output voltage slew rate by
connecting or disconnecting another internal current source IZ
to the SOFT pin, depending on the state of the system, i.e.
Startup or Active mode, and the logic state on the DPRSLPVR
pin. The SOFT-START CURRENT section of the Electrical
Specification Table shows the specs of these two current
sources.
I SS
IZ
Internal to
ISL6261
Error
Ampliflier
C SOFT
V REF
FIGURE 5. SOFT PIN CURRENT SOURCES FOR FAST AND
SLOW SLEW RATES
ISS is 41A typical and is used during startup and mode
changes. When connected to the SOFT pin, IZ adds to ISS to
get a larger current, labelled IGV in the Electrical Specification
Table, on the SOFT pin. IGV is typically 200A with a minimum
of 175A.
The IMVP-6® specification reveals the critical timing
associated with regulating the output voltage. SLEWRATE,
The ISL6261 has a thermal throttling feature. If the voltage on
the NTC pin goes below the 1.2V over-temperature threshold,
the VR_TT# pin is pulled low indicating the need for thermal
FN9251 Rev 1.00
Sep 27, 2006
Page 15 of 34
ISL6261
10uA
OCSET
R ocset
I phase
OC
1
RTN
1000pF
ESR
R par
0~10
VCC-SENSE
1000pF
330pF
Ropn2
VSEN
Co
R ntc
Cn
R drp1
VO
R drp2
DROOP
1
Vo
R series
DFB
Ropn1
DROOP
DCR
Rs
VSUM
Internal to
ISL6261
L
VSS-SENSE
To Processor
Socket Kelvin
Conections
VDIFF
FIGURE 6. SIMPLIFIED VOLTAGE DROOP CIRCUIT WITH CPU-DIE VOLTAGE SENSING AND INDUCTOR DCR CURRENT SENSING
given in the IMVP-6® specification, determines the choice of
the SOFT capacitor, CSOFT, through the following equation:
CSOFT
I GV

SLEWRATE
(EQ. 2)
If SLEWRATE is 10mV/s, and IGV is typically 200A, CSOFT is
calculated as
C SOFT  200 μA 10 mV μs   20 nF
(EQ. 3)
Choosing 0.015F will guarantee 10mV/s SLEWRATE at
minimum IGV value. This choice of CSOFT controls the startup
slew rate as well. One should expect the output voltage to slew
to the Boot value of 1.2V at a rate given by the following
equation:
dV soft
dt

I ss
41μA

 2.8 mV
μs
C SOFT 0.015 μF
(EQ. 4)
Startup Operation - CLK_EN# and PGOOD
The ISL6261 provides a 3.3V logic output pin for CLK_EN#.
The system 3.3V voltage source connects to the 3V3 pin,
which powers internal circuitry that is solely devoted to the
CLK_EN# function. The output is a CMOS signal with 4mA
sourcing and sinking capability. CMOS logic eliminates the
need for an external pull-up resistor on this pin, eliminating the
loss on the pull-up resistor caused by CLK_EN# being low in
normal operation. This prolongs battery run time. The 3.3V
supply should be decoupled to digital ground, not to analog
ground, for noise immunity.
At startup, CLK_EN# remains high until 20s after PGD_IN
going high, and Vcc-core is regulated at the Boot voltage. The
ISL6261 triggers an internal timer for the IMVP6_PWRGD
signal (PGOOD pin). This timer allows PGOOD to go high
approximately 7ms after CLK_EN# goes low.
Selecting Rbias
Static Mode of Operation - Processor Die Sensing
To properly bias the ISL6261, a reference current needs to be
derived by connecting a 147k, 1% tolerance resistor from the
RBIAS pin to ground. This provides a very accurate 10A current
source from which OCSET reference current is derived.
Remote sensing enables the ISL6261 to regulate the core
voltage at a remote sensing point, which compensates for
various resistive voltage drops in the power delivery path.
Caution should used in layout: This resistor should be placed
in the close proximity of the RBIAS pin and be connected to
good quality signal ground. Do not connect any other
components to this pin, as they will negatively impact the
performance. Capacitance on this pin may create instabilities
and should be avoided.
FN9251 Rev 1.00
Sep 27, 2006
The VSEN and RTN pins of the ISL6261 are connected to
Kelvin sense leads at the die of the processor through the
processor socket. (The signal names are Vcc_sense and
Vss_sense respectively). Processor die sensing allows the
voltage regulator to tightly control the processor voltage at the
die, free of the inconsistencies and the voltage drops due to
layouts. The Kelvin sense technique provides for extremely
tight load line regulation at the processor die side.
Page 16 of 34
ISL6261
These traces should be laid out as noise sensitive traces. For
optimum load line regulation performance, the traces
connecting these two pins to the Kelvin sense leads of the
processor should be laid out away from rapidly rising voltage
nodes (switching nodes) and other noisy traces. Common
mode and differential mode filters are recommended as shown
in Figure 6. The recommended filter resistance range is 0~10
so it does not interact with the 50k input resistance of the
differential amplifier. The filter resistor may be inserted
between VCC-SENSE and the VSEN pin. Another option is to
place one between VCC-SENSE and the VSEN pin and
another between VSS-SENSE and the RTN pin. The need of
these filters also depends on the actual board layout and the
noise environment.
Since the voltage feedback is sensed at the processor die, if
the CPU is not installed, the regulator will drive the output
voltage all the way up to damage the output capacitors due to
lack of output voltage feedback. Ropn1 and Ropn2 are
recommended, as shown in Figure 6, to prevent this potential
issue. Ropn1 and Ropn2, typically ranging 20~100, provide
voltage feedback from the regulator local output in the absence
of the CPU.
Setting the Switching Frequency - FSET
The R3 modulator scheme is not a fixed frequency PWM
architecture. The switching frequency increases during the
application of a load to improve transient performance.
It also varies slightly depending on the input and output
voltages and output current, but this variation is normally less
than 10% in continuous conduction mode.
Resistor Rfset (R7 in Figure 2), connected between the VW and
COMP pins of the ISL6261, sets the synthetic ripple window
voltage, and therefore sets the switching frequency. This
relationship between the resistance and the switching frequency
in CCM is approximately given by the following equation.
R fset kΩ    period(s)  0.29  2.33
(EQ. 5)
In diode emulation mode, the ISL6261 stretches the switching
period. The switching frequency decreases as the load
becomes lighter. Diode emulation mode reduces the switching
loss at light load, which is important in conserving battery
power.
54uA
NTC
V NTC
6uA
Internal to
ISL6261
VR_TT#
SW1
R NTC
SW2
RS
1.23V
1.20V
FIGURE 7. CIRCUITRY ASSOCIATED WITH THE THERMAL
THROTTLING FEATURE
Figure 7 shows the circuitry associated with the thermal
throttling feature of the ISL6261. At low temperature, SW1 is
on and SW2 connects to the 1.20V side. The total current
going into the NTC pin is 60µA. The voltage on the NTC pin is
higher than 1.20V threshold voltage and the comparator output
is low. VR_TT# is pulled up high by an external resistor.
Temperature increase will decrease the NTC thermistor
resistance. This decreases the NTC pin voltage. When the
NTC pin voltage drops below 1.2V, the comparator output goes
high to pull VR_TT# low, signalling a thermal throttle. In
addition, SW1 turns off and SW2 connects to 1.23V, which
decreases the NTC pin current by 6µA and increases the
threshold voltage by 30mV. The VR_TT# signal can be used by
the system to change the CPU operation and decrease the
power consumption. As the temperature drops, the NTC pin
voltage goes up. If the NTC pin voltage exceeds 1.23V,
VR_TT# will be pulled high. Figure 8 illustrates the temperature
hysteresis feature of VR_TT#. T1 and T2 (T1>T2) are two
threshold temperatures. VR_TT# goes low when the
temperature is higher than T1 and goes high when the
temperature is lower than T2.
VR_TT#
Logic_1
Voltage Regulator Thermal Throttling
lntel® IMVP-6® technology supports thermal throttling of the
processor to prevent catastrophic thermal damage to the
voltage regulator. The ISL6261A features a thermal monitor
sensing the voltage across an externally placed negative
temperature coefficient (NTC) thermistor. Proper selection and
placement of the NTC thermistor allows for detection of a
designated temperature rise by the system.
FN9251 Rev 1.00
Sep 27, 2006
Logic_0
T2
T1
T (oC)
FIGURE 8. VR_TT# TEMPERATURE HYSTERISIS
Page 17 of 34
ISL6261
The NTC thermistor’s resistance is approximately given by the
following formula:
R
NTC
(T )  R
NTCTo
1
1
b(

)
 e T  273 To  273
(EQ. 6)
T is the temperature of the NTC thermistor and b is a constant
determined by the thermistor material. To is the reference
temperature at which the approximation is derived. The most
commonly used To is 25C. For most commercial NTC
thermistors, there is b = 2750k, 2600k, 4500k or 4250k.
From the operation principle of VR_TT#, the NTC resistor
satisfies the following equation group:
R NTC (T1 )  Rs 
1.20V
 20kΩ
60 μA
(EQ. 7)
R NTC (T2 )  Rs 
1.23V
 22.78kΩ
54 μA
(EQ. 8)
From Equation 7 and Equation 8, the following can be derived:
RNTC(T2 )  RNTC(T1 )  2.78kΩ
(EQ. 9)
Substitution of Equation 6 into Equation 9 yields the required
nominal NTC resistor value:
2.78kΩ  e
RNTCTo 
e
b(
1
)
T2  273
b(
1
)
To  273
b(
e
(EQ. 10)
1
)
T1  273
One example of using Equations 10, 11 and 12 to design a
thermal throttling circuit with the temperature hysteresis 100C
to 105C is illustrated as follows. Since T1 = 105C and
T2 = 100C, if we use a Panasonic NTC with b = 4700,
Equation 9 gives the required NTC nominal resistance as
R NTC_To  431kΩ
The NTC thermistor datasheet gives the resistance ratio as
0.03956 at 100C and 0.03322 at 105C. The b value of 4700k
in Panasonic datasheet only covers up to 85C; therefore,
using Equation 11 is more accurate for 100C design and the
required NTC nominal resistance at 25C is 438k. The
closest NTC resistor value from manufacturers is 470k. So
Equation 12 gives the series resistance as follows:
Rs  20k  R NTC _ 105C  20k  15.61k  4.39k
The closest standard value is 4.42k. Furthermore, Equation
13 gives the NTC resistance at T2:
RNTC _ T 2  2.78k  RNTC _ T 1  18.39k
The NTC branch is designed to have a 470k NTC and a 4.42k
resistor in series. The part number of the NTC thermistor is
ERTJ0EV474J. It is a 0402 package. The NTC thermistor
should be placed in the spot that gives the best indication of
the temperature of the voltage regulator. The actual
temperature hysteretic window is approximately 105C to
100C.
In some cases, the constant b is not accurate enough to
approximate the resistor value; manufacturers provide the
resistor ratio information at different temperatures. The
nominal NTC resistor value may be expressed in another way
as follows:
RNTCTo 
2.78kΩ
Λ
Λ
(EQ. 11)
R NTC (T2 )  R NTC (T1 )

where R NTC (T ) is the normalized NTC resistance to its
nominal value. The normalized resistor value on most NTC
thermistor datasheets is based on the value at 25C.
Once the NTC thermistor resistor is determined, the series
resistor can be derived by:
Rs 
1.20V
 R NTC (T1 )  20kΩ  R NTC_T1
60 μA
(EQ. 12)
Once RNTCTo and Rs is designed, the actual NTC resistance at
T2 and the actual T2 temperature can be found in:
RNTC _ T 2  2.78k  RNTC _ T 1
T2 _ actual 
1
R NTC _ T2
1
ln(
)  1 ( 273  To )
b
R NTCTo
FN9251 Rev 1.00
Sep 27, 2006
(EQ. 13)
 273
(EQ. 14)
Page 18 of 34
ISL6261
10uA
Rocset
OCSET
VO
OC
Rs
VSUM
Internal to
ISL6261
DROOP
DFB
Vdcr
Rseries
Rpar
Rntc
R drp1
VO
Cn
1
R drp2
DROOP
Rn
Io DCR
(Rntc+Rseries) Rpar
Rntc+Rseries+Rpar
FIGURE 9. EQUIVALENT MODEL FOR DROOP CIRCUIT USING DCR SENSING
Static Mode of Operation - Static Droop Using DCR
Sensing
The ISL6261 has an internal differential amplifier to accurately
regulate the voltage at the processor die.
For DCR sensing, the process to compensate the DCR
resistance variation takes several iterative steps. Figure 2
shows the DCR sensing method. Figure 9 shows the simplified
model of the droop circuitry. The inductor DC current generates
a DC voltage drop on the inductor DCR. Equation 15 gives this
relationship.
V DCR  I o  DCR
(EQ. 15)
An R-C network senses the voltage across the inductor to get
the inductor current information. Rn represents the NTC
network consisting of Rntc, Rseries and Rpar. The choice of Rs
will be discussed in the next section.
The first step in droop load line compensation is to choose Rn
and Rs such that the correct droop voltage appears even at
light loads between the VSUM and VO nodes. As a rule of
thumb, the voltage drop across the Rn network, Vn, is set to be
0.5-0.8 times VDCR. This gain, defined as G1, provides a fairly
reasonable amount of light load signal from which to derive the
droop voltage.
The NTC network resistor value is dependent on the
temperature and is given by:
Rn (T ) 
( Rseries  Rntc )  R par
Rseries  Rntc  R par
G1, the gain of Vn to VDCR, is also dependent on the
temperature of the NTC thermistor:

G1 (T ) 
Rn (T )
Rn (T )  Rs
The inductor DCR is a function of the temperature and is
approximately given by
DCR(T )  DCR25C  (1  0.00393 * (T  25))
(EQ. 18)
in which 0.00393 is the temperature coefficient of the copper.
The droop amplifier output voltage divided by the total load
current is given by:
Rdroop  G1(T)  DCR (T )  k droopamp
(EQ. 19)
Rdroop is the actual load line slope. To make Rdroop
independent of the inductor temperature, it is desired to have:
G1 (T )  (1  0.00393 * (T  25))  G1t arg et
(EQ. 20)
where G1target is the desired ratio of Vn/VDCR. Therefore, the
temperature characteristics G1 is described by:
G 1 (T ) 
G 1 t arg et
(1  0.00393* (T  25)
(EQ. 21)
For different G1 and NTC thermistor preference, Intersil
provides a design spreadsheet to generate the proper value of
Rntc, Rseries, Rpar.
(EQ. 16)
Rdrp1 (R11 in Figure 2) and Rdrp2 (R12 in Figure 2) sets the
droop amplifier gain, according to Equation 22:
k droopamp  1 
FN9251 Rev 1.00
Sep 27, 2006
(EQ. 17)
Rdrp 2
R drp1
(EQ. 22)
Page 19 of 34
ISL6261
After determining Rs and Rn networks, use Equation 23 to
calculate the droop resistances Rdrp1 and Rdrp2.
Rdrp 2  (
Rdroop
DCR  G1(25 o C )
 1)  Rdrp1
(EQ. 23)
excessively upon load application to create a system failure.
Figure 12 shows the transient response when Cn is too large.
Vcore is sluggish in drooping to its final value. There will be
excessive overshoot if a load occurs during this time, which
may potentially hurt the CPU reliability.
Rdroop is 2.1mV/A per lntel® IMVP-6® specification.
The effectiveness of the Rn network is sensitive to the coupling
coefficient between the NTC thermistor and the inductor. The
NTC thermistor should be placed in close proximity of the
inductor.
To verify whether the NTC network successfully compensates
the DCR change over temperature, one can apply full load
current, and wait for the thermal steady state, and see how
much the output voltage deviates from the initial voltage reading.
Good thermal compensation can limit the drift to less than 2mV.
If the output voltage decreases when the temperature increases,
that ratio between the NTC thermistor value and the rest of the
resistor divider network has to be increased. Following the
evaluation board value and layout of NTC placement will
minimize the engineering time.
The current sensing traces should be routed directly to the
inductor pads for accurate DCR voltage drop measurement.
However, due to layout imperfection, the calculated Rdrp2 may
still need slight adjustment to achieve optimum load line slope.
It is recommended to adjust Rdrp2 after the system has
achieved thermal equilibrium at full load. For example, if the
max current is 20A, one should apply 20A load current and
look for 42mV output voltage droop. If the voltage droop is
40mV, the new value of Rdpr2 is calculated by:
R drp 2 _ new
42 mV

( R drp 1  R drp 2 )  R drp 1
40 mV
(EQ. 24)
For the best accuracy, the effective resistance on the DFB and
VSUM pins should be identical so that the bias current of the
droop amplifier does not cause an offset voltage. The effective
resistance on the VSUM pin is the parallel of Rs and Rn, and
the effective resistance on the DFB pin is the parallel of Rdrp1
and Rdrp2.
Dynamic Mode of Operation – Droop Capacitor
Design in DCR Sensing
Figure 10 shows the desired waveforms during load transient
response. Vcore needs to be as square as possible at Icore
change. The Vcore response is determined by several factors,
namely the choice of output inductor and output capacitor, the
compensator design, and the droop capacitor design.
The droop capacitor refers to Cn in Figure 9. If Cn is designed
correctly, its voltage will be a high-bandwidth analog voltage of
the inductor current. If Cn is not designed correctly, its voltage
will be distorted from the actual waveform of the inductor
current and worsen the transient response. Figure 11 shows
the transient response when Cn is too small. Vcore may sag
FN9251 Rev 1.00
Sep 27, 2006
Vcore
icore
Icore
Vcore
Vcore
Vcore= IcoreRdroop
FIGURE 10. DESIRED LOAD TRANSIENT RESPONSE
WAVEFORMS
icore
Vcore
Vcore
FIGURE 11. LOAD TRANSIENT RESPONSE WHEN Cn IS TOO
SMALL
icore
Vcore
Vcore
FIGURE 12. LOAD TRANSIENT RESPONSE WHEN Cn IS TOO
LARGE
The current sensing network consists of Rn, Rs and Cn. The
effective resistance is the parallel of Rn and Rs. The RC time
constant of the current sensing network needs to match the
L/DCR time constant of the inductor to get correct
representation of the inductor current waveform. Equation 25
shows this equation:
 R  Rs 
L
  Cn
  n
DCR  Rn  Rs 
(EQ. 25)
Solving for Cn yields
L
C n  DCR
Rn  Rs
Rn  Rs
(EQ. 26)
Page 20 of 34
ISL6261
For example: L = 0.45H, DCR = 1.1m, Rs = 7.68k, and
Rn = 3.4k
0.45H
0.0011
 174nF
Cn 
parallel(7.68k ,3.4k )
(EQ. 27)
Since the inductance and the DCR typically have 20% and 7%
tolerance respectively, the L/DCR time constant of each
individual inductor may not perfectly match the RC time
constant of the current sensing network. In mass production,
this effect will make the transient response vary a little bit from
board to board. Compared with potential long-term damage on
CPU reliability, an immediate system failure is worse. So it is
desirable to avoid the waveforms shown in Figure 11. It is
recommended to choose the minimum Cn value based on the
maximum inductance so only the scenarios of Figures 10 and
12 may happen. It should be noted that, after calculation, finetuning of Cn value may still be needed to account for board
parasitics. Cn also needs to be a high-grade cap like X7R with
low tolerance. Another good option is the NPO/COG (class-I)
capacitor, featuring only 5% tolerance and very good thermal
characteristics. But the NPO/COG caps are only available in
small capacitance values. In order to use such capacitors, the
resistors and thermistors surrounding the droop voltage
sensing and droop amplifier need to be scaled up 10X to
reduce the capacitance by 10X. Attention needs to be paid in
balancing the impedance of droop amplifier.
Dynamic Mode of Operation - Compensation
Parameters
The voltage regulator is equivalent to a voltage source equal to
VID in series with the output impedance. The output
impedance needs to be 2.1m in order to achieve the 2.1mV/A
load line. It is highly recommended to design the compensation
such that the regulator output impedance is 2.1m. A type-III
compensator is recommended to achieve the best
performance. Intersil provides a spreadsheet to design the
compensator parameters. Figure 13 shows an example of the
spreadsheet. After the user inputs the parameters in the blue
font, the spreadsheet will calculate the recommended
compensator parameters (in the pink font), and show the loop
gain curves and the regulator output impedance curve. The
loop gain curves need to be stable for regulator stability, and
the impedance curve needs to be equal to or smaller than
2.1m in the entire frequency range to achieve good transient
response.
Droop using Discrete Resistor Sensing Static/Dynamic Mode of Operation
Figure 3 shows a detailed schematic using discrete resistor
sensing of the inductor current. Figure 14 shows the equivalent
circuit. Since the current sensing resistor voltage represents
the actual inductor current information, Rs and Cn simply
provide noise filtering. The most significant noise comes from
the ESL of the current sensing resistor. A low low ESL sensing
resistor is strongly recommended. The recommended Rs is
100 and the recommended Cn is 220pF. Since the current
sensing resistance does not appreciably change with
temperature, the NTC network is not needed for thermal
compensation.
Droop is designed the same way as the DCR sensing
approach. The voltage on the current sensing resistor is given
by the following equation:
Vrsen  Rsen  I o
(EQ. 28)
Equation 21shows the droop amplifier gain. So the actual
droop is given by
 Rdrp 2 

Rdroop  Rsen  1 
 R 
drp
1


(EQ. 29)
Solving for Rdrp2 yields:
 Rdroop 
Rdrp 2  Rdrp1  
 1
R

 sen
(EQ. 30)
For example: Rdroop = 2.1m. If Rsen = 1m and Rdrp1 = 1k,
easy calculation gives that Rdrp2 is 1.1k.
The current sensing traces should be routed directly to the
current sensing resistor pads for accurate measurement.
However, due to layout imperfections, the calculated Rdrp2 may
still need slight adjustment to achieve optimum load line slope.
It is recommended to adjust Rdrp2 after the system has
achieved thermal equilibrium at full load.
The user can choose the actual resistor and capacitor values
based on the recommendation and input them in the
spreadsheet, then see the actual loop gain curves and the
regulator output impedance curve.
Caution needs to be used in choosing the input resistor to the
FB pin. Excessively high resistance will cause an error to the
output voltage regulation due to the bias current flowing in the
FB pin. It is recommended to keep this resistor below 3k.
FN9251 Rev 1.00
Sep 27, 2006
Page 21 of 34
VSS
ISL6261
FIGURE 13. AN EXAMPLE OF ISL6261 COMPENSATION SPREADSHEET
FN9251 Rev 1.00
Sep 27, 2006
Page 22 of 34
ISL6261
10uA
OCSET
Rocset
VO
OC
Rs
VSUM
Internal to
ISL6261
DROOP
DFB
Vrsen
Cn
VO
I o Rsen
R drp1
1
R drp2
DROOP
FIGURE 14. EQUIVALENT MODEL FOR DROOP CIRCUIT USING DISCRETE RESISTOR SENSING
Typical Performance (Data Taken on ISL6261 Eval1 Rev. C Evaluation Board)
FIGURE 15. CCM EFFICIENCY, VID = 1.1V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FIGURE 16. CCM LOAD LINE AND THE SPEC, VID = 1.1V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FIGURE 17. DEM EFFICIENCY, VID = 0.7625V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FIGURE 18. DEM LOAD LINE AND THE SPEC, VID = 0.7625V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FN9251 Rev 1.00
Sep 27, 2006
Page 23 of 34
ISL6261
Typical Performance (Data Taken on ISL6261 Eval1 Rev. C Evaluation Board) (Continued)
FIGURE 19. ENHANCED DEM EFFICIENCY, VID = 0.7625V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FIGURE 20. ENHANCED DEM LOAD LINE, VID = 0.7625V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FIGURE 21. ENHANCED DEM EFFICIENCY, VID = 1.1V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
FIGURE 22. ENHANCED DEM LOAD LINE, VID = 1.1V,
VIN1 = 8V, VIN2 = 12.6V AND VIN3 = 19V
5V/div
0.5V/div
10V/div
FIGURE 23. SOFT-START, VIN = 19V, Io = 0A, VID = 1.5V,
Ch1: VR_ON, Ch2: Vo, Ch4: PHASE
FN9251 Rev 1.00
Sep 27, 2006
FIGURE 24. SOFT-START, VIN = 19V, Io = 0A, VID = 1.1V,
Ch1: VR_ON, Ch2: Vo, Ch4: PHASE
Page 24 of 34
ISL6261
Typical Performance (Data Taken on ISL6261 Eval1 Rev. C Evaluation Board) (Continued)
5V/div
0.2V/div
0.2V/div
5V/div
5V/div
5V/div
10V/div
5V/div
FIGURE 25. VBOOT TO VID, VIN = 19V, Io = 2A, VID = 1.5V,
Ch1: PGD_IN, Ch2: Vo, Ch3: CLK_EN#,
Ch4: PHASE
FIGURE 26. VBOOT TO VID, VIN = 19V, Io = 2A, VID = 0.7625V,
Ch1: PGD_IN, Ch2: Vo, Ch3: PGOOD,
Ch4: CLK_EN
5V/div
0.5V/div
7.5ms
5V/div
10V/div
FIGURE 27. CLK_EN AND PGOOD ASSERTION DELAY,
VIN=19V, Io=2A, VID=1.1V, Ch1: CLK_EN#,
Ch2: Vo, Ch3: PGOOD, Ch4: PHASE
FIGURE 28. SHUT DOWN, VIN = 19V, Io = 0.5A, VID = 1.5V,
Ch1: VR_ON, Ch2: Vo, Ch3: PGOOD,
Ch4: PHASE
FIGURE 29. SOFT START INRUSH CURRENT, VIN = 19V,
Io = 0.5A, VID = 1.1V, Ch1: DROOP-VO
(2.1mV = 1A), Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
FIGURE 30. VIN TRANSIENT TEST, VIN = 819V, Io = 2A,
VID = 1.1V, Ch1: Vo, Ch3: VIN, Ch4: PHASE
FN9251 Rev 1.00
Sep 27, 2006
Page 25 of 34
ISL6261
Typical Performance (Data Taken on ISL6261 Eval1 Rev. C Evaluation Board) (Continued)
FIGURE 31. C4 ENTRY/EXIT, VIN = 12.6V, Io = 0.7A,
HFM VID = 1.1V, LFM VID = 0.9V, C4
VID = 0.7625V, FDE = DPRSLPVR,
Ch1: DPRSTP#, Ch2: Vo, Ch3: DPRSLPVR/FDE,
Ch4: PHASE
100A/us
50A/us
FIGURE 33. LOAD STEP UP RESPONSE IN CCM,
VIN = 8V, Io = 2A20A at 100A/us, VID = 1.1V,
Ch1: Io, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
100A/us
50A/us
FIGURE 35. LOAD TRANSIENT RESPONSE IN CCM
VIN = 8V, Io = 2A20A, VID = 1.1V,
Ch1: Io, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
FN9251 Rev 1.00
Sep 27, 2006
FIGURE 32. VID TOGGLING, VIN = 12.6V, Io= 0.7A,
HFM VID = 1.1V, LFM VID = 0.9V,
Ch1: SOFT, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
FIGURE 34. LOAD STEP DOWN RESPONSE IN CCM
VIN = 8V, Io = 20A2A at 100A/us, VID = 1.1V,
Ch1: Io, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
100A/us
50A/us
FIGURE 36. LOAD TRANSIENT RESPONSE IN ENHANCED
DEM, VIN = 8V, Io = 2A20A, VID = 1.1V,
Ch1: Io, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
Page 26 of 34
ISL6261
Typical Performance (Data Taken on ISL6261 Eval1 Rev. C Evaluation Board) (Continued)
50A/us
100A/us
FIGURE 37. LOAD TRANSIENT RESPONSE IN ENHANCED
DEM, VIN = 8V, Io = 2A20A, VID = 1.1V,
Ch1: Io, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
FIGURE 38. LOAD TRANSIENT RESPONSE IN ENHANCED
DEM, VIN = 8V, Io = 2A20A, VID = 1.1V,
Ch1: Io, Ch2: Vo, Ch3: Vcomp, Ch4: PHASE
120us
FIGURE 39. OVERCURRENT PROTECTION, VIN = 12.6V,
Io = 0A28A, VID = 1.1V, Ch1: DROOP-VO
(2.1mV = 1A), Ch2: Vo, Ch3: PGOOD,
Ch4: PHASE
FIGURE 40. OVERVOLTAGE (>1.7V) PROTECTION,
VIN = 12.6V, Io = 2A, VID = 1.1V,
Ch2: Vo, Ch3: PGOOD, Ch4: PHASE
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Intersil products are sold by description only. Intersil may modify the circuit design and/or specifications of products at any time without notice, provided that such
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FN9251 Rev 1.00
Sep 27, 2006
Page 27 of 34
ISL6261
ISL6261 Eval1 Rev. C Evaluation Board Schematic
FN9251 Rev 1.00
Sep 27, 2006
Page 28 of 34
ISL6261
ISL6261 Eval1 Rev. C Evaluation Board Schematic
FN9251 Rev 1.00
Sep 27, 2006
(Continued)
Page 29 of 34
ISL6261
ISL6261 Eval1 Rev. C Evaluation Board Schematic
FN9251 Rev 1.00
Sep 27, 2006
(Continued)
Page 30 of 34
ISL6261
ISL6261 Eval1 Rev. C Evaluation Board Schematic
FN9251 Rev 1.00
Sep 27, 2006
(Continued)
Page 31 of 34
ISL6261
ISL6261 Eval1 Rev. C Evaluation Board Schematic
FN9251 Rev 1.00
Sep 27, 2006
(Continued)
Page 32 of 34
ISL6261
Package Outline Drawing
L40.6x6
40 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 2, 9/06
4X 4.5
6.00
36X 0.50
A
B
6
PIN 1
INDEX AREA
6
PIN #1 INDEX AREA
40
31
30
1
6.00
4 . 10 ± 0 . 15
21
10
0.15
(4X)
11
20
TOP VIEW
0.10 M C A B
40X 0 . 4 ± 0 . 1
4 0 . 23 +0 . 07 / -0 . 05
BOTTOM VIEW
SEE DETAIL "X"
0.10 C
0 . 90 ± 0 . 1
(
C
BASE PLANE
( 5 . 8 TYP )
SEATING PLANE
0.08 C
SIDE VIEW
4 . 10 )
( 36X 0 . 5 )
C
0 . 2 REF
5
( 40X 0 . 23 )
0 . 00 MIN.
0 . 05 MAX.
( 40X 0 . 6 )
DETAIL "X"
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Dimension b applies to the metallized terminal and is measured
between .015mm and 0.30mm from the terminal tip.
5. Tiebar shown (if present) is a non-functional feature.
6. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 indentifier may be
either a mold or mark feature.
FN9251 Rev 1.00
Sep 27, 2006
Page 33 of 34
ISL6261
Package Outline Drawing
L48.7x7
48 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 3, 9/06
4X 5.5
7.00
A
44X 0.50
B
37
6
PIN 1
INDEX AREA
6
PIN #1 INDEX AREA
48
1
7.00
36
4. 30 ± 0 . 15
12
25
(4X)
0.15
13
24
0.10 M C A B
48X 0 . 40± 0 . 1
TOP VIEW
4 0.23 +0.07 / -0.05
BOTTOM VIEW
SEE DETAIL "X"
( 6 . 80 TYP )
(
0.10 C
BASE PLANE
0 . 90 ± 0 . 1
4 . 30 )
C
SEATING PLANE
0.08 C
SIDE VIEW
( 44X 0 . 5 )
C
0 . 2 REF
5
( 48X 0 . 23 )
( 48X 0 . 60 )
0 . 00 MIN.
0 . 05 MAX.
TYPICAL RECOMMENDED LAND PATTERN
DETAIL "X"
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Dimension b applies to the metallized terminal and is measured
between .015mm and 0.30mm from the terminal tip.
5. Tiebar shown (if present) is a non-functional feature.
6. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 indentifier may be
either a mold or mark feature.
FN9251 Rev 1.00
Sep 27, 2006
Page 34 of 34
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