ISL70001SEH, ISL70001SRH Datasheet

Radiation Hardened and SEE Hardened 6A Synchronous
Buck Regulator
ISL70001SEH, ISL70001SRH
Features
The ISL70001SEH, ISL70001SRH are radiation hardened and
SEE hardened high efficiency monolithic synchronous buck
regulators with integrated MOSFETs. This single chip power
solution operates over an input voltage range of 3V to 5.5V and
provides a tightly regulated output voltage that is externally
adjustable from 0.8V to ~85% of the input voltage. Output load
current capacity is 6A for TJ < +145°C.
• ±1% reference voltage over line, load, temperature and
radiation
High integration and class leading radiation tolerance makes
the ISL70001SEH, ISL70001SRH ideal choices to power many
of today’s small form factor applications. Two devices can be
synchronized to provide a complete power solution for large
scale digital ICs, like field programmable gate arrays (FPGAs)
that require separate core and I/O voltages.
Applications
• Current mode control for excellent dynamic response
• Full Mil-temp range operation (TA = -55°C to +125°C)
• High efficiency > 90%
• Fixed 1MHz operating frequency
• Available in a thermally enhanced heatsink package - R48.B
• Operates from 3V to 5.5V supply
• Adjustable output voltage
- Two external resistors set VOUT from 0.8V to ~85% of VIN
• Bi-directional SYNC pin allows two devices to be synchronized
180° out-of-phase
• Starts into pre-biased load
• FPGA, CPLD, DSP, CPU Core or I/O Voltages
• Low-Voltage, High-Density Distributed Power Systems
Related Literature
• ISL70001SRHEVAL1Z Evaluation Board, AN1518
• Single Event Effects (SEE) Testing of the ISL70001SRH
Synchronous Buck Regulator
• Total Dose Testing of the ISL70001SRH Hardened Point of
Load Regulator
• Power-good output voltage monitor
• Adjustable analog soft-start
• Input undervoltage, output undervoltage and output
overcurrent protection
• Electrically screened to DLA SMD 5962-09225
• QML qualified per MIL-PRF-38535 requirements
• EH Version is wafer-by-wafer acceptance tested for ELDRS
• Radiation hardness
- Total dose [50-300rad(Si)/s] . . . . . . . . . 100krad(Si) (min)
- Total dose [<10mrad(Si)/s]. . . . . . . . . . . . 50krad(Si) (min)
• SEE hardness
- SEL and SEB LETeff . . . . . . . . . . . 86.4MeV/mg/cm2 (min)
- SEFI X-section (LETeff = 86.4MeV/mg/cm2) 1.4 x 10-6 cm2
(max)
- SET LETeff (< 1 Pulse Perturbation) 86.4MeV/mg/cm2 (min)
95
5V SUPPLY
ISL70001SEH
CORE
SYNCH
ISL75051SEH
AUX
ISL70001SEH
I/O
RAD TOLERANT
FPGA
EFFICIENCY (%)
90
85
80
75
SYNCH
70
0
1
2
3
4
5
6
LOAD CURRENT (A)
FIGURE 1. TYPICAL APPLICATION
February 24, 2014
FN7956.2
1
FIGURE 2. EFFICIENCY 5V INPUT TO 3.3V OUTPUT, TA = +25°C
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2011, 2013, 2014. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
ISL70001SEH, ISL70001SRH
AVDD
AGND
DVDD
DGND
EN
Functional Block Diagram
POWER-ON
RESET (POR)
PORSEL
PVINx
CURRENT
SENSE
SS
SLOPE
COMPENSATION
SOFT
START
EA
FB
GM
PWM
CONTROL
LOGIC
GATE
DRIVE
LXx
COMPENSATION
PGNDx
UV
POWER-GOOD
PGOOD
REF
PWM
REFERENCE
0.6V
TDI
BIT
TRIM
TDO
ZAP
SYNC
M/S
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FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Ordering Information
ORDERING NUMBER
(Note 2)
PART NUMBER
TEMP. RANGE
(°C)
PACKAGE
(RoHS Compliant)
PKG.
DWG. #
5962R0922502VXC
ISL70001SEHVF (Note 1)
-55 to +125
48 Ld CQFP
R48.A
5962R0922502VYC
ISL70001SEHVFE (Note 1)
-55 to +125
48 Ld CQFP With Heatsink
R48.B
5962R0922502V9A
ISL70001SEHVX
-55 to +125
Die
5962R0922501VXC
ISL70001SRHVF (Note 1)
-55 to +125
48 Ld CQFP
R48.A
5962R0922501QXC
ISL70001SRHQF (Note 1)
-55 to +125
48 Ld CQFP
R48.A
5962R0922501V9A
ISL70001SRHVX
-55 to +125
Die
ISL70001SRHF/PROTO
ISL70001SRHF/PROTO (Note 1)
-55 to +125
48 Ld CQFP
R48.A
ISL70001SEHFE/PROTO
ISL70001SEHFE/PROTO (Note 1)
-55 to +125
48 Ld CQFP With Heatsink
R48.B
ISL70001SRHX/SAMPLE
ISL70001SRHX/SAMPLE
-55 to +125
Die
ISL70001SRHEVAL1Z
Evaluation Board
ISL70001ASEHEV1Z
Evaluation Board
NOTES:
1. These Intersil Pb-free Hermetic packaged products employ 100% Au plate - e4 termination finish, which is RoHS compliant and compatible with both
SnPb and Pb-free soldering operations.
2. Specifications for Rad Hard QML devices are controlled by the Defense Logistics Agency Land and Maritime (DLA). The SMD numbers listed in the
Ordering Information table on must be used when ordering.
Pin Configuration
3
PVIN3
7
1 48 47 46 45 44 43
42
ZAP
8
41
LX3
TDI
9
40
PGND3
TDO
10
39
PGND3
PGOOD
11
38
PGND4
SS
12
37
PGND4
DVDD
13
36
LX4
DVDD
14
35
PVIN4
DGND
15
34
PVIN4
DGND
16
33
PVIN5
AGND
17
32
PVIN5
AGND
31
18
19 20 21 22 23 24 25 26 27 28 29 30
PGND5
PGND6
PGND6
LX6
PVIN6
PVIN6
PORSEL
EN
FB
REF
* HEATSINK
PGND5
M/S
AVDD
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PVIN2
2
PVIN2
PGND1
3
LX2
LX1
4
PGND2
PVIN1
5
PGND2
PVIN1
6
PGND1
SYNC
ISL70001SEH, ISL70001SRH
(48 LD CQFP)
TOP VIEW
PVIN3
LX5
* Heatsink available in R48.B package
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Pin Descriptions
PIN NUMBER
PIN NAME
DESCRIPTION
1, 2, 27, 28, 29, 30,
37, 38, 39, 40, 47,
48
PGNDx
These pins are the power grounds associated with the corresponding internal power blocks. Connect these pins
directly to the ground plane. These pins should also connect to the negative terminals of the input and output
capacitors. Locate the input and output capacitors as close as possible to the IC.
3, 26, 31, 36, 41,
46
LXx
These pins are the outputs of the corresponding internal power blocks and should be connected to the output
filter inductor. Internally, these pins are connected to the synchronous MOSFET power switches. To minimize
voltage undershoot, it is recommended that a Schottky diode be connected from these pins to PGNDx. The
Schottky diode should be located as close as possible to the IC.
4, 5, 24, 25, 32, 33,
34, 35, 42, 43, 44,
45
PVINx
These pins are the power supply inputs to the corresponding internal power blocks. These pins must be
connected to a common power supply rail, which must fall in the range of 3V to 5.5V. Bypass these pins directly
to PGNDx with ceramic capacitors located as close as possible to the IC.
6
SYNC
This pin is the synchronization I/O for the IC. When configured as an output (Master Mode), this pin drives the
SYNC input of another ISL70001SEH, ISL70001SRH. When configured as an input (Slave Mode), this pin
accepts the SYNC output from another ISL70001SEH, ISL70001SRH or an external clock. Synchronization of
the slave unit is 180° out-of-phase with respect to the master unit. If synchronizing to an external clock, the
clock must be SEE hardened and the frequency must be within the range of 1MHz ±20%.
7
M/S
This pin is the Master/Slave input for selecting the direction of the bi-directional SYNC pin. For SYNC = Output
(Master Mode), connect this pin to DVDD. For SYNC = Input (Slave Mode), connect this pin to DGND.
8
ZAP
This pin is a trim input and is used to adjust various internal circuitry. Connect this pin to DGND.
9
TDI
This pin is the test data input of the internal BIT circuitry. Connect this pin to DGND.
10
TDO
This pin is the test data output of the internal BIT circuitry. Connect this pin to DGND.
11
PGOOD
This pin is the power-good output. This pin is an open drain logic output that is pulled to DGND when the output
voltage is outside a ±11% typical regulation window. This pin can be pulled up to any voltage from 0V to 5.5V,
independent of the supply voltage. A nominal 1k to 10k pull-up resistor is recommended. Bypass this pin
to DGND with a 10nF ceramic capacitor to mitigate SEE.
12
SS
This pin is the soft-start input. Connect a ceramic capacitor from this pin to DGND to set the soft-start output
ramp time in accordance with Equation 1:
t SS = C SS  V REF  I SS
(EQ. 1)
where:
tSS = Soft-start output ramp time
CSS = Soft-start capacitor
VREF = Reference voltage (0.6V typical)
ISS = Soft-start charging current (23µA typical)
Soft-start time is adjustable from approximately 2ms to 200ms.
The range of the soft-start capacitor should be 82nF to 8.2µF, inclusive.
13, 14
DVDD
These pins are the bias supply inputs to the internal digital control circuitry. Connect these pins together at the
IC and locally filter them to DGND using a 1 resistor and a 1µF ceramic capacitor. Locate both filter
components as close as possible to the IC.
15, 16
DGND
These pins are the digital ground associated with the internal digital control circuitry. Connect these pins
directly to the ground plane.
17, 18
AGND
These pins are the analog ground associated with the internal analog control circuitry. Connect these pins
directly to the ground plane.
19
AVDD
This pin is the bias supply input to the internal analog control circuitry. Locally filter this pin to AGND using a 1
resistor and a 1µF ceramic capacitor. Locate both filter components as close as possible to the IC.
20
REF
This pin is the internal reference voltage output. Bypass this pin to AGND with a 220nF ceramic capacitor
located as close as possible to the IC. The bypass capacitor is needed to mitigate SEE. No current (sourcing or
sinking) is available from this pin.
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February 24, 2014
ISL70001SEH, ISL70001SRH
Pin Descriptions (Continued)
PIN NUMBER
PIN NAME
21
FB
DESCRIPTION
This pin is the voltage feedback input to the internal error amplifier. Connect a resistor from FB to VOUT and
from FB to AGND to adjust the output voltage in accordance with Equation 2:
V OUT = V REF   1 +  R T  R B  
(EQ. 2)
where:
VOUT = Output voltage
VREF = Reference voltage (0.6V typical)
RT = Top divider resistor (Must be 1k)
RB = Bottom divider resistor
The top divider resistor must be 1k to mitigate SEE. Connect a 4.7nF ceramic capacitor across RT to mitigate SEE
and to improve stability margins.
22
EN
This pin is the enable input to the IC. This is a comparator type input with a rising threshold of 0.6V and
programmable hysteresis. Driving this pin above 0.6V enables the IC. Bypass this pin to AGND with a 10nF
ceramic capacitor to mitigate SEE.
23
PORSEL
This pin is the input for selecting the rising and falling POR (Power-On-Reset) thresholds. For a nominal 5V
supply, connect this pin to DVDD. For a nominal 3.3V supply, connect this pin to DGND. For nominal supply
voltages between 5V and 3.3V, connect this pin to DGND.
Heatsink
The heatsink is electrically isolated and should be connected to a thermal chassis of any potential which offers
optimal thermal relief.
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FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Typical Application Schematic
PVIN1
LX1
PVIN2
LX2
PVIN3
LX3
PVIN4
LX4
PVIN5
LX5
5V
100µF
1µF
1µF
1µH
LX6
PVIN6
1Ω
1kΩ
FB
1µF
ISL70001SRH, ISL70001SEH
0V TO 5.5V
AGND
499Ω
PGOOD
DVDD
VSENSE
470µF
20V
3A
AVDD
1Ω
1.8V
6A
10nF
1µF
SYNC
DGND
REF
EN
10nF
220nF
M/S
PORSEL
TDI
SS
TDO
100nF
PGND6
PGND5
PGND4
PGND3
PGND2
PGND1
ZAP
FIGURE 3. 5V INPUT SUPPLY VOLTAGE WITH MASTER MODE SYNCHRONIZATION
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FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Typical Application Schematic (Continued)
PVIN1
LX1
PVIN2
LX2
PVIN3
LX3
PVIN4
LX4
PVIN5
LX5
3.3V
100µF
1µF
1µF
1µH
PVIN6
1Ω
LX6
470µF
20V
3A
DVDD
4.7nF
1kΩ
FB
1µF
ISL70001SRH, ISL70001SEH
0V TO 5.5V
DGND
1Ω
1.8V
6A
499Ω
PGOOD
AVDD
10nF
1µF
VSENSE
SYNC
AGND
REF
EN
10nF
220nF
M/S
PORSEL
TDI
SS
TDO
100nF
PGND6
PGND5
PGND4
PGND3
PGND2
PGND1
ZAP
FIGURE 4. 3.3V INPUT SUPPLY VOLTAGE WITH SLAVE MODE SYNCHRONIZATION
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FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Absolute Maximum Ratings
Thermal Information
AVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AGND - 0.3V to AGND + 6.5V
DVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DGND - 0.3V to DGND +6.5V
LXx, PVINx . . . . . . . . . . . . . . . . . . . . . . . . . . . PGNDx - 0.3V to PGNDx + 6.5V
AVDD - AGND, DVDD - DGND . . . . . . . . . . . . . . . . . . . . PVINx - PGNDx ± 0.3V
Signal Pins (Note 7) . . . . . . . . . . . . . . . . . . . . . AGND - 0.3V to AVDD + 0.3V
Digital Control Pins (Note 8) . . . . . . . . . . . . . . DGND - 0.3V to DVDD + 0.3V
PGOOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DGND - 0.3V to DGND + 6.5V
SS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DGND - 0.3V to DGND + 2.5V
Thermal Resistance (Typical)
JA (°C/W) JC (°C/W)
48 Ld CQFP R48.A (Notes 3, 5) . . . . . . . . .
36.5
3
48 Ld CQFP R48.B (Notes 4, 6) . . . . . . . . .
19
1.3
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . .+145°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Absolute Maximum Ratings (Note 9)
AVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AGND - 0.3V to AGND + 5.7V
DVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DGND - 0.3V to DGND + 5.7V
LXx, PVINx . . . . . . . . . . . . . . . . . . . . . . . . . . . PGNDx - 0.3V to PGNDx + 5.7V
AVDD - AGND, DVDD - DGND . . . . . . . . . . . . . . . . . . . . PVINx - PGNDx ± 0.3V
Signal Pins (Note 7) . . . . . . . . . . . . . . . . . . . . . AGND - 0.3V to AVDD + 0.3V
Digital Control Pins (Note 8) . . . . . . . . . . . . . . DGND - 0.3V to DVDD + 0.3V
PGOOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DGND - 0.3V to DGND + 5.7V
SS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DGND - 0.3V to DGND + 2.5V
Recommended Operating Conditions
AVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AGND + 3V to 5.5V
DVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DGND + 3V to 5.5V
PVINx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PGNDx + 3V to 5.5V
AVDD - AGND, DVDD - DGND . . . . . . . . . . . . . . . . . . . . PVINx - PGNDx ± 0.1V
Signal Pins (Note 8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AGND to AVDD
Digital Control Pins (Note 9) . . . . . . . . . . . . . . . . . . . . . . . . . .DGND to DVDD
REF, SS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internally Set
GND, TDI, TDO, TPGM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DGND
ILXx (TJ ≤ +145°C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 1.0A
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-55°C to +125°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
3. JA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
4. 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.
5. For JC, the “case temp” location is the center of the package underside.
6. For JC, the “case temp” location is the center of the exposed metal heatsink on the package underside.
7. EN, FB, PORSEL and REF pins.
8. M/S, SYNC, TDI, TDO and ZAP pins.
9. For Operation in a heavy ion environment tested at LET = 86.4 MeV•cm2/mg with +125°C (TC).
Electrical Specifications
Unless otherwise noted, VIN = AVDD = DVDD = PVINx = EN = M/S = 3V or 5.5V;
GND = AGND = DGND = PGNDx = TDI = TDO = ZAP = 0V; FB = 0.65V; PORSEL = VIN for 4.5V ≤ VIN ≤ 5.5V and GND for VIN < 4.5V,
SYNC = LXx = Open Circuit; PGOOD is pulled up to VIN with a 1kΩ resistor; REF is bypassed to GND with a 220nF capacitor; SS is bypassed to GND with a
100nF capacitor; IOUT = 0A; TA = TJ = +25°C. (Note 12). Boldface limits apply over the operating temperature range, -55°C to +125°C; over a total iodizing
dose of 100krad(Si) with exposure at a high dose rate of 50 - 300krad(Si)/s; and over a total iodizing dose of 50krad(Si) with exposure at a low dose rate
of <10mrad(Si)/s.
PARAMETER
TYP
MAX
(Note 13)
UNITS
VIN = 5.5V (Note 10)
40
65
mA
VIN = 3.6V (Note 10)
25
45
mA
VIN = 5.5V, EN = GND (Note 11)
6
12
mA
VIN = 3.6V, EN = GND (Note 11)
3
6
mA
0.594
0.6
0.606
V
TEST CONDITIONS
MIN
(Note 13)
POWER SUPPLY
Operating Supply Current
Shutdown Supply Current
OUTPUT VOLTAGE
Reference Voltage Tolerance
Output Voltage Tolerance
VOUT = 0.8V to 2.5V for VIN = 4.5V to 5.5V,
VOUT = 0.8V to 2.5V for VIN = 3V to 3.6V,
IOUT = 0A to 6A (Notes 14, 15)
-2
0
2
%
Feedback (FB) Input Leakage Current
VIN = 5.5V, VFB = 0.6V
-1
0
1
µA
0.85
1
1.15
MHz
PWM CONTROL LOGIC
Oscillator Accuracy
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FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Electrical Specifications
Unless otherwise noted, VIN = AVDD = DVDD = PVINx = EN = M/S = 3V or 5.5V;
GND = AGND = DGND = PGNDx = TDI = TDO = ZAP = 0V; FB = 0.65V; PORSEL = VIN for 4.5V ≤ VIN ≤ 5.5V and GND for VIN < 4.5V,
SYNC = LXx = Open Circuit; PGOOD is pulled up to VIN with a 1kΩ resistor; REF is bypassed to GND with a 220nF capacitor; SS is bypassed to GND with a
100nF capacitor; IOUT = 0A; TA = TJ = +25°C. (Note 12). Boldface limits apply over the operating temperature range, -55°C to +125°C; over a total iodizing
dose of 100krad(Si) with exposure at a high dose rate of 50 - 300krad(Si)/s; and over a total iodizing dose of 50krad(Si) with exposure at a low dose rate
of <10mrad(Si)/s. (Continued)
PARAMETER
TEST CONDITIONS
External Oscillator Range
MIN
(Note 13)
TYP
MAX
(Note 13)
UNITS
0.8
1
1.2
MHz
Minimum LXx On Time
VIN = 5.5V, Test Mode
110
150
ns
Minimum LXx Off Time
VIN = 5.5V, Test Mode
40
100
ns
Minimum LXx On Time
VIN = 3V, Test Mode
150
210
ns
Minimum LXx Off Time
VIN = 3V, Test Mode
50
100
ns
Master/Slave (M/S) Input Voltage
Input High Threshold
VIN - 0.5
Input Low Threshold
1.3
0.5
V
1
µA
Master/Slave (M/S) Input Leakage Current VIN = 5.5V, M/S = GND or VIN
-1
0
Synchronization (SYNC) Input Voltage
2.3
1.7
Input High Threshold, M/S = GND
Input Low Threshold, M/S = GND
-1
V
1.2
V
1.5
1
V
0
1
µA
Synchronization (SYNC) Input Leakage
Current
VIN = 5.5V, M/S = GND, SYNC = GND or VIN
Synchronization (SYNC) Output Voltage
VIN - VOH @ IOH = -1mA
0.15
0.4
V
[email protected] IOL = 1mA
0.15
0.4
V
POWER BLOCKS
Upper Device rDS(ON)
VIN = 3V, 0.4A Per Power Block, Test Mode (Note 15)
122
215
346
m
Lower Device rDS(ON)
VIN = 3V, 0.4A Per Power Block, Test Mode (Note 15)
77
146
236
m
LXx Output Leakage
VIN = 5.5V, EN = LXx = GND, Single LXx Output
-1
0
VIN = 5.5V, EN = GND, LXx = VIN, Single LXx Output
Deadtime
Within a Single Power Block or between Power
Blocks (Note 15)
Efficiency
0
1.7
µA
15
µA
5
ns
VIN = 3.3V, VOUT = 1.8V, IOUT = 3A
90
%
VIN = 5V, VOUT = 2.5V, IOUT = 3A
92
%
1.4
V
POWER-ON RESET
POR Select (PORSEL)
Input High Threshold
VIN - 0.5
Input Low Threshold
1.2
0.5
V
POR Select (PORSEL) Input Leakage
Current
VIN = 5.5V, PORSEL = GND or VIN
-1
0
1
µA
VIN POR
Rising Threshold, PORSEL = VIN
4.1
4.25
4.45
V
Hysteresis, PORSEL = VIN
225
325
425
mV
Rising Threshold, PORSEL = GND
2.65
2.8
2.95
V
Hysteresis, PORSEL = GND
90
175
260
mV
0.56
0.6
0.64
V
VIN = 5.5V, EN = GND or VIN
-3
0
3
µA
EN = 0.3V
6.4
11
16.6
µA
SS = GND
20
23
27
µA
2.2
4.7

Enable (EN) Input Voltage
Rising/Falling Threshold
Enable (EN) Input Leakage Current
Enable (EN) Sink Current
SOFT-START
Soft-Start Source Current
Soft-Start Discharge ON-Resistance
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9
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Electrical Specifications
Unless otherwise noted, VIN = AVDD = DVDD = PVINx = EN = M/S = 3V or 5.5V;
GND = AGND = DGND = PGNDx = TDI = TDO = ZAP = 0V; FB = 0.65V; PORSEL = VIN for 4.5V ≤ VIN ≤ 5.5V and GND for VIN < 4.5V,
SYNC = LXx = Open Circuit; PGOOD is pulled up to VIN with a 1kΩ resistor; REF is bypassed to GND with a 220nF capacitor; SS is bypassed to GND with a
100nF capacitor; IOUT = 0A; TA = TJ = +25°C. (Note 12). Boldface limits apply over the operating temperature range, -55°C to +125°C; over a total iodizing
dose of 100krad(Si) with exposure at a high dose rate of 50 - 300krad(Si)/s; and over a total iodizing dose of 50krad(Si) with exposure at a low dose rate
of <10mrad(Si)/s. (Continued)
PARAMETER
TEST CONDITIONS
MIN
(Note 13)
Soft-Start Discharge Time
TYP
MAX
(Note 13)
256
UNITS
Clock Cycles
POWER-GOOD SIGNAL
Rising Threshold
VFB as a% of VREF, Test Mode
107
111
115
%
Rising Hysteresis
VFB as a% of VREF, Test Mode
2
3.5
5
%
Falling Threshold
VFB as a% of VREF, Test Mode
85
89
93
%
Falling Hysteresis
VFB as a% of VREF, Test Mode
2
3.5
5
%
Power-Good Drive
VIN = 3V, PGOOD = 0.4V, EN = GND
Power-Good Leakage
VIN = PGOOD = 5.5V
7.3
8.2
mA
0.001
1
µA
PROTECTION FEATURES
Undervoltage Monitor
Undervoltage Trip Threshold
VIN = 3V, VFB as a% of VREF, Test mode
71
75
79
%
Undervoltage Recovery Threshold
VIN = 3V, VFB as a% of VREF, Test mode
84
88
92
%
Overcurrent Trip Level
LX4 Power Block, Test Mode, (Note 16)
1.3
1.9
2.5
A
Overcurrent or Short-Circuit Duty-Cycle
VIN = 3V, SS Interval = 200µs, Test Mode, Fault
Interval Divided by Hiccup Interval
0.8
5
%
Overcurrent Monitor
NOTES:
10. L = 1µH connected to Lx
11. 1kΩ PGOOD pull-up resistor is not populated.
12. Typical values shown are not guaranteed. Guaranteed min/max values are provided in the SMD.
13. Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design.
14. Limits do not include tolerance of external feedback resistors. The 0A to 6A output current range may be reduced by Minimum LXx On Time and
Minimum LXx Off Time specifications.
15. Limits established by characterization or analysis and are not production tested.
16. During an output short-circuit, peak current through the power block(s) can continue to build beyond the overcurrent trip level by up to 3A. With all
six power blocks connected, peak current through the power blocks and output inductor could reach (6 x 2.5A) + 3A = 18A. The output inductor must
support this peak current without saturating.
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10
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Functional Description
The ISL70001SEH, ISL70001SRH are monolithic, fixed
frequency, current-mode synchronous buck regulators with user
configurable power blocks. Two devices can be used to provide a
total DC/DC solution for FPGAs, CPLDs, DSPs and CPUs.
The ISL70001SEH, ISL70001SRH utilize peak current-mode
control with integrated compensation and switches at a fixed
frequency of 1MHz. Two devices can be synchronized 180°
out-of-phase to reduce input RMS ripple current. These attributes
reduce the number and size of external components required,
while providing excellent output transient response. The internal
synchronous power switches are optimized for high efficiency
and good thermal performance.
The chip features a comparator type enable input that provides
flexibility. It can be used for simple digital on/off control or,
alternately, can provide undervoltage lockout capability by using
two external resistors to precisely sense the level of an external
supply voltage. A power-good signal indicates when the output
voltage is within ±11% typical of the nominal output voltage.
Regulator start-up is controlled by an analog soft-start circuit,
which can be adjusted from approximately 2ms to 200ms by
using an external capacitor.
The ISL70001SEH, ISL70001SRH incorporate fault protection for
the regulator. The protection circuits include input undervoltage,
output undervoltage, and output overcurrent.
Power Blocks
The power output stage of the regulator consists of six 1A
capable power blocks that are paralleled to provide full 6A
output current capability. The block diagram in Figure 5 shows a
top level view of the individual power blocks.
PVIN1
LX1
PGND1
POWER BLOCK 1
PVIN2
LX2
PGND2
POWER BLOCK 2
POWER BLOCK 5
PVIN5
LX5
PGND5
PVIN3
LX3
PGND3
POWER BLOCK 3
POWER BLOCK 4
PVIN4
LX4
PGND4
POWER BLOCK 6
PVIN6
LX6
PGND6
FIGURE 5. POWER BLOCK DIAGRAM
Each power block has a power supply input pin, PVINx, a phase
output pin, LXx, and a power supply ground pin, PGNDx. All PVINx
pins must be connected to a common power supply rail and all
PGNDx pins must be connected to a common ground. LXx pins
should be connected to the output inductor based on the
required load current, but must include the LX4 pin. For example,
if 3A of output current is needed, any three LXx pins can be
connected to the inductor as long as one of them is the LX4 pin.
The unused LXx pins should be left unconnected. Connecting all
six LXx pins to the output inductor provides a maximum 6A of
output current. See the “Typical Application Schematic” on
page 6 for pin connection guidance.
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11
A scaled pilot device associated with each power block provides
current feedback. Power block 4 contains the master pilot device
and this is why it must be connected to the output inductor.
Main Control Loop
During normal operation, the internal top power switch is turned
on at the beginning of each clock cycle. Current in the output
inductor ramps up until the current comparator trips and turns
off the top power MOSFET. The bottom power MOSFET turns on
and the inductor current ramps down for the rest of the cycle.
The current comparator compares the output current at the
ripple current peak to a current pilot. The error amplifier monitors
VOUT and compares it with an internal reference voltage. The
output voltage of the error amplifier drives a proportional current
to the pilot. If VOUT is low, the current level of the pilot is
increased and the trip off current level of the output is increased.
The increased output current raises VOUT until it is in agreement
with the reference voltage.
Output Voltage Selection
The output voltage can be adjusted using an external resistor
divider as shown in Figure 6.
VREF = 0.6V
CREF = 220nF
RT = 1k
CC = 4.7nF
L
LXx OUT
VOUT
COUT
RT
ERROR
AMPLIFIER
FB
+
CC
VREF
REF
RB
CREF
FIGURE 6. OUTPUT VOLTAGE SELECTION
RT should be selected as 1kto mitigate SEE. RT should be
shunted by a 4.7nF ceramic capacitor, CC, to mitigate SEE and to
improve loop stability margins. The REF pin should be bypassed
to AGND with a 220nF ceramic capacitor to mitigate SEE. It
should be noted that no current (sourcing or sinking) is available
from the REF pin. RB can be determined from Equation 3. The
designer can configure the output voltage from 0.8V to 85% of
the input voltage.
V REF
R B = R T  -------------------------------V
–V
OUT
(EQ. 3)
REF
Switching Frequency/Synchronization
The ISL70001SEH, ISL70001SRH feature an internal oscillator
running at a fixed frequency of 1MHz ±15% over recommended
operating conditions. The regulator can be configured to run from
the internal oscillator or can be synchronized to another
ISL70001SEH, ISL70001SRH or a SEE hardened external clock
with a frequency range of 1MHz ±20%.
To run the regulator from the internal oscillator, connect the M/S
pin to DVDD. In this case, the output of the internal oscillator
appears on the SYNC pin. To synchronize the regulator to the
SYNC output of another regulator or to a SEE hardened external
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
clock, connect the M/S pin to DGND. In this case, the SYNC pin is
an input that accepts an external synchronizing signal. When
synchronizing multiple devices, Slave regulators are
synchronized 180° out-of-phase with respect to the SYNC output
of a Master regulator or to an external clock.
VR = 0.6V
IEN = 11µA
CEN = 10nF
VIN1
PVINx
Operation Initialization
The ISL70001SEH, ISL70001SRH initialize based on the state of
the power-on reset (POR) monitor of the PVINx inputs and the
state of the EN input. Successful initialization prompts a
soft-start interval, and the regulator begins slowly ramping the
output voltage. Once the commanded output voltage is within
the proper window of operation, the power-good signal changes
state from low-to-high, indicating proper regulator operation.
VIN2
ENABLE
COMPARATOR
R1
EN
+
-
POR
LOGIC
CEN
VR
R2
IEN
Power-On Reset
The POR circuitry prevents the controller from attempting to
soft-start before sufficient bias is present at the PVINx pins.
The POR threshold of the PVINx pins is controlled by the PORSEL
pin. For a nominal 5V supply voltage, PORSEL should be
connected to DVDD. For a nominal 3.3V supply voltage, PORSEL
should be connected to DGND. For nominal supply voltages
between 5V and 3.3V, PORSEL should be connected to DGND.
The POR rising and falling thresholds are shown in the “Electrical
Specifications” table on Page 9.
Hysteresis between the rising and falling thresholds ensures that
small perturbations on PVINx seen during turn-on/turn-off of the
regulator do not cause inadvertent turn-off/turn-on of the
regulator. When the PVINx pins are below the POR rising
threshold, the internal synchronous power MOSFET switches are
turned off, and the LXx pins are held in a high-impedance state.
FIGURE 7. ENABLE CIRCUIT
With the part enabled and the IEN current sink off, the disable
level is set by the resistor divider. The disable level is defined by
Equation 5.
R1
V DISABLE = V R  1 + ------R2
(EQ. 5)
The difference between the enable and disable levels provide
adjustable hysteresis so that noise on VIN2 does not interfere
with the enabling or disabling of the regulator.
To mitigate SEE, the EN pin should be bypassed to the AGND pin
with a 10nF ceramic capacitor.
Soft-Start
Enable and Disable
After the POR input requirement is met, the ISL70001SEH,
ISL70001SRH remains in shutdown until the voltage at the
enable input rises above the enable threshold. Figure 7 shows
the enable circuit features a comparator type input. In addition to
simple logic on/off control, the enable circuit allows the level of
an external voltage to precisely gate the turn-on/turn-off of the
regulator. An internal IEN current sink with a typical value of
11µA is only active when the voltage on the EN pin is below the
enable threshold. The current sink pulls the EN pin low. As VIN2
rises, the enable level is not set exclusively by the resistor divider
from VIN2.
Once the POR and enable circuits are satisfied, the regulator
initiates a soft-start. Figure 8 shows that the soft-start circuit
clamps the error amplifier reference voltage to the voltage on an
external soft-start capacitor connected to the SS pin.
VREF = 0.6V
ISS = 23µA
RD = 2.2Ω
RT
FB
(EQ. 4)
RB
ERROR
AMPLIFIER
With the current sink active, the enable level is defined by
Equation 4. R1 is the resistor from the EN pin to VIN2 and R2 is
the resistor from the EN pin to the AGND pin.
R1
V ENABLE = V R  1 + ------- + I EN  R1
R2
VOUT
PWM
LOGIC
+
+
SS
REF
VREF
CSS
CREF
RD
ISS
Once the voltage at the EN pin reaches the enable threshold, the
IEN current sink turns off.
FIGURE 8. SOFT-START CIRCUIT
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12
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
The soft-start capacitor is charged by an internal ISS current
source. As the soft-start capacitor is charged, the output voltage
slowly ramps to the set point determined by the reference
voltage and the feedback network. Once the voltage on the SS
pin is equal to the internal reference voltage, the soft-start
interval is complete. The controlled ramp of the output voltage
reduces the in-rush current during start-up. The soft-start output
ramp interval is defined in Equation 6 and is adjustable from
approximately 2ms to 200ms. The value of the soft-start
capacitor, CSS, should range from 8.2nF to 8.2µF, inclusive. The
peak in-rush current can be computed from Equation 7. The
soft-start interval should be long enough to ensure that the peak
in-rush current plus the peak output load current does not exceed
the overcurrent trip level of the regulator.
V REF
t SS = C SS  ------------I
(EQ. 6)
SS
V OUT
I INRUSH = C OUT  ------------t
(EQ. 7)
SS
The soft-start capacitor is immediately discharged by a 2.2
resistor whenever POR conditions are not met or EN is pulled low.
The soft-start discharge time is equal to 256 clock cycles.
Power-Good
The power-good (PGOOD) pin is an open-drain logic output that
indicates when the output voltage of the regulator is within
regulation limits. The power-good pin pulls low during shutdown
and remains low when the controller is enabled. After a
successful soft-start, the PGOOD pin releases, and the voltage
rises with an external pull-up resistor. The power-good signal
transitions low immediately when the EN pin is pulled low.
The power-good circuitry monitors the FB pin and compares it to
the rising and falling thresholds shown in the “Electrical
Specifications” table on Page 10. If the feedback voltage
exceeds the typical rising limit of 111% of the reference voltage,
the PGOOD pin pulls low. The PGOOD pin continues to pull low
until the feedback voltage falls to a typical of 107.5% of the
reference voltage. If the feedback voltage drops below a typical
of 89% of the reference voltage, the PGOOD pin pulls low. The
PGOOD pin continues to pull low until the feedback voltage rises
to a typical 92.5% of the reference voltage. The PGOOD pin then
releases and signals the return of the output voltage to within the
power-good window.
The PGOOD pin can be pulled up to any voltage from 0V to 5.5V,
independently from the supply voltage. The pull-up resistor
should have a nominal value from 1k to 10k. The PGOOD pin
should be bypassed to DGND, with a 10nF ceramic capacitor to
mitigate SEE.
Fault Monitoring and Protection
The ISL70001SEH, ISL70001SRH actively monitor output voltage
and current to detect fault conditions. Fault conditions trigger
protective measures to prevent damage to the regulator and
external load device.
Undervoltage Protection
A hysteretic comparator monitors the FB pin of the regulator. The
feedback voltage is compared to an undervoltage threshold that
is a fixed percentage of the reference voltage. Once the
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13
comparator trips, indicating a valid undervoltage condition, a
3-bit undervoltage counter increments. The counter is reset if the
feedback voltage rises back above the undervoltage threshold,
plus a specified amount of hysteresis outlined in the “Electrical
Specifications” table on Page 10. If the 3-bit counter overflows,
the undervoltage protection logic shuts down the regulator.
After the regulator shuts down, it enters a delay interval
equivalent to the soft-start interval, which allows the device to
cool. The undervoltage counter is reset when the device enters
the delay interval. The protection logic initiates a normal
soft-start once the delay interval ends. If the output successfully
soft-starts, the power-good signal goes high, and normal
operation continues. If undervoltage conditions continue to exist
during the soft-start interval, the undervoltage counter must
overflow before the regulator shuts down again. This hiccup
mode continues indefinitely until the output soft-starts
successfully.
Overcurrent Protection
A pilot device integrated into the PMOS transistor of Power Block 4
samples current each cycle. This current feedback is scaled and
compared to an overcurrent threshold based on the number of
power blocks connected. Each additional power block connected
beyond Power Block 4 increases the overcurrent limit by 2A. For
example, if three power blocks are connected, the typical current
limit threshold would be 3 x 2A = 6A.
If the sampled current exceeds the overcurrent threshold, a 3-bit
overcurrent counter increments by one LSB. If the sampled current
falls below the threshold before the counter overflows, the counter
is reset. Once the overcurrent counter reaches 111, the regulator
shuts down.
After the regulator shuts down, it enters a delay interval,
equivalent to the soft-start interval, which allows the device to
cool. The overcurrent counter is reset when the device enters the
delay interval. The protection logic initiates a normal soft-start
once the delay interval ends. If the output successfully
soft-starts, the power-good signal goes high, and normal
operation continues. If overcurrent conditions continue to exist
during the soft-start interval, the overcurrent counter must
overflow before the regulator shuts down the output again. This
hiccup mode continues indefinitely until the output soft-starts
successfully.
Note: To prevent severe negative ringing that can disturb the
overcurrent counter, it is recommended that a Schottky diode of
appropriate rating be added from the LXx pins to the PGNDx pins.
Feedback Loop Compensation
To reduce the number of external components and to simplify the
process of determining compensation components, the
ISL70001SEH, ISL70001SRH buck regulators have an internally
compensated error amplifier.
Due to the current loop feedback in peak current mode control, the
modulator has a single pole response with -20dB slope at a
frequency determined by the load (Equation 8):
1
F PO = ------------------------------------2  R O  C OUT
(EQ. 8)
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
where RO is load resistance and COUT is the output load
capacitance. For this type of modulator, a Type 2 compensation
circuit is usually sufficient.
Figure 9 shows a Type 2 amplifier and its response, along with
the responses of the current mode modulator and the converter.
C2
R2
C1
CONVERTER
R1
The output inductor and the output capacitor bank together to
form a low-pass filter responsible for smoothing the pulsating
voltage at the phase node. The filter must also provide the
transient energy until the regulator can respond. Since the filter
has low bandwidth relative to the switching frequency, it limits
the system transient response. The output capacitors must
supply or sink current while the current in the output inductor
increases or decreases to meet the load demand.
OUTPUT CAPACITOR SELECTION
EA
TYPE 2 EA
The critical load parameters in choosing the output capacitors
are the maximum size of the load step (DISTEP), the load-current
slew rate (di/dt), and the maximum allowable output voltage
deviation under transient loading (DVMAX). Capacitors are
characterized according to their capacitance, Equivalent Series
Resistance (ESR) and Equivalent Series Inductance (ESL).
GEA = 25.1dB
MODULATOR
FZ
FPO
FP
FC
At the beginning of a load transient, the output capacitors supply
all of the transient current. The output voltage initially deviates by
an amount approximated by the voltage drop across the ESL. As
the load current increases, the voltage drop across the ESR
increases linearly until the load current reaches its final value.
Neglecting the contribution of inductor current and regulator
response, the output voltage initially deviates by an amount
shown in Equation 11.
FIGURE 9. FEEDBACK LOOP COMPENSATION
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 (Equations 9 and 10).
1
F Z = ------------------------------ = 8.6kHz
2  R 2  C 1
(EQ. 9)
1
F P = ------------------------------ = 546kHz
2  R 1  C 2
(EQ. 10)
Zero frequency and amplifier high-frequency gain were chosen to
satisfy 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. Equation 13 on page 13
approximates the amount of capacitance needed to achieve an
optimal pole location depending on the number of LXx pins
connected. 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 the 1.2kHz to 30kHz range gives some additional
phase ‘boost’. Some phase boost is also be achieved by
connecting the recommended capacitor CC in parallel with the
upper resistor RT of the divider that sets the output voltage value,
as demonstrated in Figure 6.
Component Selection Guide
This design guide is intended to provide a high-level explanation
of the steps necessary to create a power converter. It is assumed
the reader is familiar with many of the basic skills and
techniques referenced in the following. In addition to this guide,
Intersil provides a complete evaluation board that includes
schematic, BOM, and an example PCB layout (see Ordering
Information table on page 3).
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Output Filter Design
14
di
V MAX  ESL  ----- +  ESR  I STEP 
dt
(EQ. 11)
The filter capacitors selected must have sufficiently low ESL and
ESR, such that the total output voltage deviation is less than the
maximum allowable ripple.
Most capacitor solutions rely on a mixture of high frequency
capacitors with relatively low capacitance in combination with
bulk capacitors having high capacitance but larger ESR.
Minimizing the ESL of the high-frequency capacitors allows them
to support the output voltage as the current increases.
Minimizing the ESR of the bulk capacitors allows them to supply
the increased current with less output voltage deviation.
Ceramic capacitors with X7R dielectric are recommended.
Alternately, a combination of low ESR solid tantalum capacitors
and ceramic capacitors with X7R dielectric may be used.
The ESR of the bulk capacitors is responsible for most of the
output voltage ripple. As the bulk capacitors sink and source the
inductor AC ripple current, a voltage, VP-P(MAX), develops across
the bulk capacitor according to Equation 12.
 V IN – V OUT V OUT
V P-P(MAX) = ESR  ---------------------------------------------L OUT  f s  V IN
(EQ. 12)
Another consideration in selecting the output capacitors is loop
stability. The total output capacitance sets the dominant pole of
the PWM. Because the ISL70001SEH, ISL70001SRH use
integrated compensation techniques, it is necessary to restrict
the output capacitance in order to optimize loop stability. The
recommended load capacitance can be estimated using
Equation 13.
1.8V
C OUT = 75F  Number of LXx Pins Connected  ------------V OUT
(EQ. 13)
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
1
ESR = ---------------------------------------------2  f ZESR   C OUT 
(EQ. 14)
In conclusion, the output capacitors must meet three criteria:
1. They must have sufficient bulk capacitance to sustain the
output voltage during a load transient while the output
inductor current is slewing to the value of the load transient.
2. The ESR must be sufficiently low to meet the desired output
voltage ripple due to the output inductor current.
3. The ESR zero should be placed, in a rather large range, to
provide additional phase margin.
OUTPUT INDUCTOR SELECTION
Once the output capacitors are selected, the maximum allowable
ripple voltage, VP-P(MAX), determines the lower limit on the
inductance as shown in Equation 15.
 V IN – V OUT V OUT
L OUT  ESR  -------------------------------------------------f s  V IN  V P-P(MAX)
(EQ. 15)
Since the output capacitors are supplying a decreasing portion of
the load current while the regulator recovers from the transient,
the capacitor voltage becomes slightly depleted. The output
inductor must be capable of assuming the entire load current
before the output voltage decreases more than VMAX. This
places an upper limit on inductance.
Equation 16 gives the upper limit on output inductance for the
case when the trailing edge of the current transient causes a
greater output voltage deviation than the leading edge.
Equation 17 addresses the leading edge. Normally, the trailing
edge dictates the inductance selection because duty cycles are
usually <50%. Nevertheless, both inequalities should be
evaluated, and inductance should be governed based on the
lower of the two results. In each equation, LOUT is the output
inductance, COUT is the total output capacitance, and IL(P-P) is
the peak-to-peak ripple current in the output inductor.
2  C OUT  V OUT
L OUT  --------------------------------------V MAX –  I L(P-P)  ESR 
 I STEP  2
2  C OUT
L OUT  ------------------------- V MAX –  I L(P-P)  ESR   V IN – V OUT


 I STEP  2
(EQ. 16)
(EQ. 17)
The other concern when selecting an output inductor is to ensure
there is adequate slope compensation when the regulator is
operated above 50% duty cycle. Since the internal slope
compensation is fixed, output inductance should satisfy
Equation 18 to ensure this requirement is met.
4.32H
L OUT  ------------------------------------------------------------------------------------------Number of LXx Pins Connected
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15
(EQ. 18)
Input Capacitor Selection
Input capacitors are responsible for sourcing the AC component
of the input current flowing into the switching power devices.
Their RMS current capacity must be sufficient to handle the AC
component of the current drawn by the switching power devices,
which is related to duty cycle. The maximum RMS current
required by the regulator is closely approximated by Equation 19.
I
RMS  MAX 
=
2
V
2 1  V IN – V OUT V OUT 
OUT 
---------------- I
+ ------   ----------------------------------  ----------------- 
12  L
V IN
V

f
 OUT  MAX 


IN
OUT s
(EQ. 19)
The important parameters to consider when selecting an input
capacitor are the voltage rating and the RMS ripple current
rating. For reliable operation, select capacitors with voltage
ratings at least 1.5x greater than the maximum input voltage.
The capacitor RMS ripple current rating should be higher than
the largest RMS ripple current required by the circuit.
Ceramic capacitors with X7R dielectric are recommended.
Alternately, a combination of low ESR solid tantalum capacitors
and ceramic capacitors with X7R dielectric may be used. The
ISL70001SEH, ISL70001SRH require a minimum effective input
capacitance of 100µF for stable operation.
Derating Current Capability
Most space programs issue specific derating guidelines for parts,
but these guidelines take the pedigree of the part into account.
For instance, a device built to MIL-PRF-38535, such as the
ISL70001, is already heavily derated from a current density
standpoint. However, a mil-temp or commercial IC that is
up-screened for use in space applications may need additional
current derating to ensure reliable operation because it was not
built to the same standards as the ISL70001.
Figure 10 shows the maximum average output current of the
ISL70001 with respect to junction temperature. These plots take
into account the worst-case current share mismatch in the power
blocks and the current density requirement of MIL-PRF-38535
(< 2 x 105 A/cm2). The plot clearly shows that the ISL70001 can
handle 12.1A at +125°C from a worst-case current density
standpoint, but the part is limited to 7.8A because that is the
lower limit of the current limit threshold with all six power blocks
connected.
MAXIMUM AVERAGE CURRENT FOR
0.1% FAILURES AT 100,000 HOURS (A)
Another stability requirement on the selection of the output
capacitor is that the ‘ESR zero’ (f ZESR) be placed at 60kHz to
90kHz. This range is set by an internal, single compensation zero
at 8.6kHz. This ESR zero location contributes to increased phase
margin of the control loop; therefore (Equation 14):
13
12
12.14
11
10.18
10
9
MINIMUM OCP
LEVEL = 7.8A
8.57
8
7.25
7
6.16
6
5
4
120
5.3
6A @ +146°C
125
130
135
140
145
150
155
JUNCTION TEMPERATURE (°C)
FIGURE 10. CURRENT vs TEMPERATURE
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
PCB Design
Thermal Management for Ceramic Package
PCB design is critical to high-frequency switching regulator
performance. Careful component placement and trace routing
are necessary to reduce voltage spikes and minimize
undesirable voltage drops. Selection of a suitable thermal
interface material is also required for optimum heat dissipation
and to provide lead strain relief. See Table 1 on page 18 for
layout x-y coordinates.
For optimum thermal performance, place a pattern of vias and a
thermal land on the top layer of the PCB directly underneath the
IC. Connect the vias to the plane, which serves as a heatsink. To
ensure good thermal contact, thermal interface material such as
a Sil-Pad or thermally conductive epoxy should be used to fill the
gap between the vias and the bottom of the ceramic package.
PCB Plane Allocation
The package leads protrude from the bottom of the package and
the leads need forming to provide strain relief. On the ceramic
bottom package R48.A, the Sil-pad or epoxy maybe be used to fill
the gap left between the PCB board and the bottom of the
package when lead forming is completed. On the heat sink
option of the package, R48.B, the lead forming should be made
so that the bottom of the heat sink and the formed leads are
flush.
Four layers of 2-ounce copper are recommended. Layer 2 should
be a dedicated ground plane with all critical component ground
connections made with vias to this layer. Layer 3 should be a
dedicated power plane split between the input and output power
rails. Layers 1 and 4 should be used primarily for signals but can
also provide additional power and ground islands, as required.
PCB Component Placement
Components should be placed as close as possible to the IC to
minimize stray inductance and resistance. Prioritize the
placement of bypass capacitors on the pins of the IC in the order
shown: REF, SS, AVDD, DVDD, PVINx (high frequency capacitors),
EN, PGOOD, PVINx (bulk capacitors).
Locate the output voltage resistive divider as close as possible to
the FB pin of the IC. The top leg of the divider should connect
directly to the POL (Point of Load), and the bottom leg of the
divider should connect directly to AGND. The junction of the
resistive divider should connect directly to the FB pin.
Locate a Schottky clamp diode as close as possible to the LXx
and PGNDx pins of the IC. A small series R-C snubber connected
from the LXx pins to the PGNDx pins may be used to damp high
frequency ringing on the LXx pins, if desired, see Figure 11.
LOUT
LXx
RS
3A
VOUT
COUT
CS
ERROR
AMPLIFIER
CC
FB
+
RT
PGNDx
VREF
Lead Strain Relief
Heat Sink Mounting Guidelines
The R48.B package option has a heat sink mounted on the
underside of the package. The following JESD51-5 guidelines
may be used to mount the package:
1. Place a thermal land on the PCB under the heat sink.
2. The land should be approximately the same size as to 1mm
larger than the 9x9mm heat sink.
3. Place an array of thermal vias below the thermal land.
- Via array size: ~8x8=64 thermal vias
- Via diameter: ~0.3mm drill diameter with plated copper on
the inside of each via.
- Via pitch: ~1.2mm.
- Vias should drop to and contact as much buried metal area
as feasible to provide the best thermal relief.
Heat Sink Electrical Potential
The heat sink is electrically isolated and unbiased. The heatsink
may be electrically connected to any potential, which offers the
best thermal relief through conductive mounting materials
(conductive epoxy, solder, etc.) or may be left unbiased through
the use of electrically non-conductive mounting materials
(non-conductive epoxy, Sil-pad, kapton film, etc.).
RB
REF
CREF
FIGURE 11. SCHOTTKY DIODE AND R-C SNUBBER
PCB Layout
Use a small island of copper to connect the LXx pins of the IC to
the output inductor on Layers 1 and 4. To minimize capacitive
coupling to the power and ground planes, void the copper on
Layers 2 and 3 adjacent to the island. Place most of the island of
Layer 4 to minimize the amount of copper that must be voided
from the ground plane (Layer 2).
Keep all other signal traces as short as possible.
For an example layout, see AN1518.
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16
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Weight Characteristics
BACKSIDE FINISH
Silicon
Weight of Packaged Device
ASSEMBLY RELATED INFORMATION
1.602 Grams typical - R48.A Package
2.440 Grams typical - R48.B Package
Substrate Potential - Package R48.A and R48.B: PGND
Die Characteristics
Metal Lid Potential
Electrically Isolated -Package R48.A
PGND - Package R48.B
Die Dimensions
5720µm x 5830µm (225.2 mils x 229.5 mils)
Thickness: 483µm ± 25.4µm (19.0 mils ± 1 mil)
ADDITIONAL INFORMATION
Interface Materials
Worst Case Current Density
< 2 x 105 A/cm2
GLASSIVATION
Transistor Count
Type: Silicon Oxide and Silicon Nitride
Thickness: 0.3µm ± 0.03µm to 1.2µm ± 0.12µm
25030
TOP METALLIZATION
Layout Characteristics
Type: AlCu (0.5%)
Thickness: 2.7µm ±0.4µm
Step and Repeat
5720µm x 5830µm
Connect PGND to PGNDx
SUBSTRATE
Type: Silicon
Isolation: Junction
Metallization Mask Layout ISL70001SEH, ISL70001SRH
LX1
SYNC PVIN1
PGND1
PGND2
LX2
PVIN2
PVIN3
M/S
ZAP
LX3
TDI
TDO
PGND3
PGOOD
PGND4
SS
LX4
DVDD
PVIN4
PVIN5
DGND
PGND
LX5
AGND
ORIGIN
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AVDD
17
REF
FB
EN PORSEL
PVIN6
LX6
PGND6
PGND5
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
TABLE 1. LAYOUT X-Y COORDINATES
PAD NUMBER
X
(µm)
Y
(µm)
dX
(µm)
dY
(µm)
BOND WIRES
PER PAD
AVDD
15
478
263
135
135
1
REF
16
865
263
135
135
1
FB
17
1295
263
135
135
1
EN
18
1751
263
135
135
1
PORSEL
19
2151
263
135
135
1
PVIN6
20
2838
188
521
135
3
LX6
21
3449
188
521
135
3
PGND6
22
4060
188
521
135
3
PGND5
23
4845
188
521
135
3
LX5
24
5449
925
135
521
3
PVIN5
25
5449
1651
135
521
3
PVIN4
26
5449
2263
135
521
3
LX4
27
5449
2874
135
521
3
PGND4
28
5449
3485
135
521
3
PGND3
29
5449
4096
135
521
3
LX3
30
5449
4745
135
521
3
PVIN3
31
4941
5559
521
135
3
PVIN2
32
4137
5559
521
135
3
LX2
33
3449
5559
521
135
3
PGND2
34
2838
5559
521
135
3
PGND1
1
2227
5559
521
135
3
LX1
2
1578
5559
521
135
3
PVIN1
3
962
5559
521
135
3
SYNC
4
544
5559
135
135
1
M/S
5
226
5280
135
135
1
ZAP
6
226
4910
135
135
1
TDI
7
226
4540
135
135
1
TDO
8
226
4170
135
135
1
PGOOD
9
226
3777
135
135
1
SS
10
226
3425
135
135
1
DVDD
11
226
2566
135
333
2
DGND
12
226
1538
135
333
2
PGND
13
226
1018
135
135
1
AGND
14
226
654
135
135
1
PAD NAME
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18
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to the web to make sure that
you have the latest revision.
DATE
REVISION
CHANGE
February 24, 2014
FN7956.2
Added Note 10 on Page 10.
Added Note 11 on Page 10.
Removed MSL note from the ordering information on page 2 as it is not applicable to hermetic packages.
Added Note 2 for ordering information table on Page 3.
Added ISL70001SRH throughout datasheet.
Page 3: Added ISL70001SRHQF and ISL70001SRHVX to the odering information table.
May 20, 2013
FN7956.1
Added heat sink mounting guidelines on Page 16.
Added “Weight Characteristics” on Page 17.
Added label “Origin” to Metallization Mask Layout on Page 17.
May 6, 2013
Page 3, ordering information table: Removed the word "(HEATSINK)" under the first column, and added to
rows 2 & 6 in the fourth column "48 ld CQFP with Heatsink”.
Page 8, thermal information table: Changed note 6, from removed exposed metal pad to exposed metal
Heatsink.
May 3, 2013
Updated ordering information table on Page 3 as follow: Added ISL7000SRHVF. Added “Heatsink” to help
distinguish between the two package types. Thermal Resistance on Page 8 as follow: changed note 3 from
“low” to “high” effective” thermal conductivity test board type and added note 4 “direct attach”.
May 2, 2013
Page 2: Added ISL70001SEHVFE, ISL70001SEHFE/PROTO parts to ordering information table and added
Package DWG# column to table.
Added POD: R48.A and R48.
November 30, 2011
FN7956.0
Initial Release
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19
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Package Outline Drawing
R48.A
48 CERAMIC QUAD FLATPACK PACKAGE (CQFP)
Rev 3, 10/12
1.118 (28.40)
1.080 (27.43)
0.572 (14.53)
0.555 (14.10)
#1 #48
0.287 (7.29)
0.253 (6.43)
0.040 (1.02) BSC
PIN 1
INDEX AREA
0.572 (14.53)
0.555 (14.10)
1.118 (28.40)
1.080 (27.43)
0.007 (0.18) MIN
0.015 (0.38)
0.008 (0.20)
0.015 (0.38) MIN
TOP VIEW
0.099 (2.51)
0.076 (1.93)
0.016 (0.41)
0.009 (0.23)
SIDE VIEW
NOTE:
1. All dimensions are in inches (millimeters).
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20
FN7956.2
February 24, 2014
ISL70001SEH, ISL70001SRH
Package Outline Drawing
R48.B
48 CERAMIC QUAD FLATPACK PACKAGE (CQFP) WITH BOTTOM HEATSINK
Rev 0, 10/12
1.118 (28.40)
1.080 (27.43)
0.572 (14.53)
0.555 (14.10)
#1 #48
0.287 (7.29)
0.253 (6.43)
0.040 (1.016) BSC
PIN 1
INDEX AREA
1.118 (28.40)
1.080 (27.43)
0.572 (14.53)
0.555 (14.10)
0.012 (0.30)
0.008 (0.20)
TOP VIEW
0.131 (3.33)
0.105 (2.67)
0.042 (1.067) REF
0.026 (0.66) MIN. 2
0.013 (0.33)
0.009 (0.23)
HEATSINK
SIDE VIEW
0.359 (9.12)
0.349 (8.87)
HEATSINK
0.359 (9.12)
0.349 (8.87)
PIN 1
INDEX AREA
NOTES:
1. All dimensions are in inches (millimeters)
2. Dimension shall be measured at point of exit
(beyond the meniscus) of the lead from the body.
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21
#1 #48
BOTTOM VIEW
FN7956.2
February 24, 2014