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®
Data Sheet
March 7, 2006
ISL6273
FN9256.0
1.2A Low Quiescent Current 1.5MHz High
Efficiency Synchronous Buck Regulator
ISL6273 is a 1.2A, 1.5MHz step-down regulator, which is
ideal for powering low-voltage microprocessors in compact
devices such as PDAs and cellular phones. It is optimized
for generating low output voltages down to 0.8V. The supply
voltage range is from 2.7V to 5.5V allowing the use of a
single Li+ cell, three NiMH cells or a regulated 5V input. It
has guaranteed minimum output current of 1.2A. 1.5MHz
pulse-width modulation (PWM) switching frequency allows
using small external components. It has flexible operation
mode selection of forced PWM mode and low IQ mode with
as low as 25µA quiescent current for highest light load
efficiency to maximize battery life.
The ISL6273 includes a pair of low on-resistance P-channel
and N-channel internal MOSFETs to maximize efficiency and
minimize external component count. 100% duty-cycle
operation allows less than 200mV dropout voltage at 1.2A.
The ISL6273 offers a 200ms Power-On-Reset (POR) timer
at power up. The timer output can be reset by RSI. When
shutdown, ISL6273 discharges the output capacitor. Other
features include internal digital soft-start, enable for power
sequence, overcurrent protection, and thermal shutdown.
The ISL6273 is offered in a 10 Ld 3x3mm DFN package with
1mm maximum height. The complete converter occupies
less than 1 cm2 area.
Ordering Information
PART
NUMBER
(NOTE)
TEMP.
PART RANGE
MARKING (°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL6273IRZ 273Z
-40 to 85 10 Ld 3x3 DFN L10.3x3C
ISL6273IRZ-T 273Z
-40 to 85 10 Ld 3x3 DFN L10.3x3C
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.
Features
• High efficiency Synchronous Buck Regulator with up to
95% Efficiency
• 200ms Reset Timer
• Discharge Output Cap when Shutdown
• 2.7V to 5.5V Supply Voltage
• 3% Output Accuracy Over Temperature/Load/Line
• 1.2A Guaranteed Output Current
• 25µA Quiescent Supply Current in IQ Mode
• Selectable Forced PWM Mode and IQ Mode
• Less than 1µA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle for Lowest Dropout
• Internal Loop Compensation
• Internal Digital Soft-Start
• Peak Current Limiting, Short Circuit Protection
• Over-Temperature Protection
• Enable
• Small 10 Ld 3x3mm DFN
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• Single Li-Ion Battery-Powered Equipment
• DSP Core Power
• PDAs and Palmtops
Pinout
ISL6273 (10 LD 3X3 DFN)
TOP VIEW
PVIN 1
VCC 2
EN 3
POR 4
MODE 5
10 PHASE
9 PGND
8 SGND
7 FB
6 RSI
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2006. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.

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ISL6273
Absolute Maximum Ratings (Reference to SGND)
Supply Voltage (PVIN, VCC) . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V
EN, RSI, MODE, PHASE, POR . . . . . . . . . . . . . -0.3V to VCC+0.3V
FB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V
PGND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 0.3V
Recommended Operating Conditions
PVIN Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.5V
Load Current Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 1.2A
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . .-40°C to 85°C
Thermal Information
Thermal Resistance (Notes 1, 2)
θJA (°C/W) θJC (°C/W)
3x3 DFN Package . . . . . . . . . . . . . .
44
5.5
Junction Temperature Range. . . . . . . . . . . . . . . . . . . -40°C to 125°C
Storage Temperature Range . . . . . . . . . . . . . . . . . . . -65°C to 150°C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTES:
1. θJA 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. θJC, “case temperature” location is at the center of the exposed metal pad on the package underside. See Tech Brief TB379.
Electrical Specifications
PARAMETER
Unless otherwise noted, all parameter limits are guaranteed over the recommended operating conditions and
the typical specification are measured at the following conditions: TA = 25°C, VPVIN = VVCC = 3.6V, EN = VCC,
RSI = 0V, MODE = VCC, L = 1.8µH, C1 = 10µF, C2 = 10µF, IOUT = 0A (see the Typical Application Circuit).
SYMBOL
TEST CONDITIONS
MIN TYP MAX UNITS
SUPPLY
VCC Undervoltage Lockout Threshold
VUVLO Rising
Falling
- 2.5 2.7
2.2 2.4
-
V
V
Quiescent Supply Current
IPVIN
MODE = VCC, no load at the output
MODE = SGND, no load at the output
- 25 50 µA
- 5 8 mA
Shut Down Supply Current
OUTPUT REGULATION
ISD VCC = PVIN = 5.5V, EN = low
- 0.1 2 µA
FB Regulation Voltage
FB Bias Current
Output Voltage Accuracy
Line Regulation
Maximum Output Current
VFB TA = 0°C to 85°C
TA = -40°C to 85°C
IFB FB = 0.75V
PVIN = VO + 0.5V to 5.5V, Io = 0 to 1.2A ,
TA = -40°C to 85°C
PVIN = VO + 0.5V to 5.5V (minimal 2.7V)
0.784 0.8 0.816
V
0.78 0.8 0.82
V
- 0.1 - µA
-3 - 3 %
- 0.2 - %/V
1.2 - - A
COMPENSATION
Error Amplifier Trans-conductance
Adjustable version, design info only
- 20 - µA/V
PHASE
P-Channel MOSFET On Resistance
PVIN = 3.6V, Io = 200mA
- 0.12 0.22
PVIN = 2.7V, Io = 200mA
-
0.16 0.27
N-Channel MOSFET On Resistance
PVIN = 3.6V, Io = 200mA
- 0.11 0.22
PVIN = 2.7V, Io = 200mA
-
0.15 0.27
P-Channel MOSFET Peak Current Limit
PHASE Maximum Duty Cycle
IPK
1.5 2.1 2.6
- 100 -
A
%
PWM Switching Frequency
PHASE Minimum On Time
fS TA = -40°C to 85°C
MODE = low (forced PWM mode)
1.35 1.5 1.75 MHz
- - 140 ns
Soft Start-Up Time
- 1.1 - ms
2 FN9256.0
March 7, 2006

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ISL6273
Electrical Specifications
PARAMETER
Unless otherwise noted, all parameter limits are guaranteed over the recommended operating conditions and
the typical specification are measured at the following conditions: TA = 25°C, VPVIN = VVCC = 3.6V, EN = VCC,
RSI = 0V, MODE = VCC, L = 1.8µH, C1 = 10µF, C2 = 10µF, IOUT = 0A (see the Typical Application Circuit).
SYMBOL
TEST CONDITIONS
MIN TYP MAX UNITS
POR
Output Low Voltage
Sinking 1mA, FB = 0.7V
- - 0.3 V
Delay Time
150 200 275
ms
POR Pin Leakage Current
POR = VCC = 3.6V
- 0.01 0.1 µA
Minimum Supply Voltage for Valid POR Signal
1.2 - - V
Internal PGOOD Low Rising Threshold
Percentage of Nominal Regulation Voltage 89.5 92 94.5
%
Internal PGOOD Low Falling Threshold
Percentage of Nominal Regulation Voltage
85
88
91
%
Internal PGOOD High Rising Threshold
Percentage of Nominal Regulation Voltage 105.5 108 110.5
%
Internal PGOOD High Falling Threshold
Percentage of Nominal Regulation Voltage 102 105 108
%
Internal PGOOD Delay Time
- 50 - µs
EN, MODE, RSI
Logic Input Low
- - 0.4 V
Logic Input High
1.4 - - V
Logic Input Leakage Current
Pulled up to 5.5V
- 0.1 1 µA
Thermal Shutdown
- 150 -
°C
Thermal Shutdown Hysteresis
- 25 - °C
3 FN9256.0
March 7, 2006

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Typical Operating Performance
ISL6273
100
VO = 2.8V
90
80
VO = 1.2V
VO = 2.5V
70
60
50
40
0.1
1 10 100
LOAD CURRENT (mA)
1000
FIGURE 1. EFFICIENY vs LOAD CURRENT (VIN = 3.6V)
3.37
3.36
3.35
3.34
3.33
VIN = 3.6V
3.32
3.31
3.3
0.1
1 10 100
LOAD CURRENT (mA)
1000
FIGURE 2. VOUT vs LOAD CURRENT (VIN = 3.6V)
100
90
80
VIN = 2.7V
70
60
50
40
0.1
1 10 100
LOAD CURRENT (mA)
1000
FIGURE 3. EFFICIENCY vs LOAD CURRENT (VO = 1.8V)
1.84
1.82
1.8
1.78
VIN = 2.7V
1.76
1.74
0.1
1 10 100
LOAD CURRENT (mA)
1000
FIGURE 4. VOUT vs LOAD CURRENT (VIN = 2.7V)
0.07
INPUT CURRENT IN PFM MODE OF 2.8V
0.06
0.05
0.04
0.03
0.02
0.01
0
2.9 3.4 3.9 4.4 4.9
VIN VOLTAGE RANGE (2.9V-5.5V)
FIGURE 5. IQ vs VIN (PFM)
5.4
4
7
INPUT CURRENT IN PWM MODE OF 2.8V
6
5
4
3
2
1
0
2.9 3.4 3.9 4.4 4.9
VIN VOLTAGE RANGE (2.9V-5.5V)
FIGURE 6. IQ vs VIN (PWM)
5.4
FN9256.0
March 7, 2006

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ISL6273
Typical Operating Performance (Continued)
1.605
1.6
1.595
1.59
1.585
1.58
1.575
1.57
2.7 3.2 3.7 4.2 4.7 5.2
VIN (V)
FIGURE 7. SWITCHING FREQUENCY vs VIN
1.61
1.608
1.606
1.604
1.602
1.6
2.7
3.7
VIN (V)
4.7
FIGURE 8. LINE REGULATION (IO = 1A)
1.61
1.605
1.6
1.595
1.59
0 200 400 600 800 1000
IO (mA)
FIGURE 9. LOAD REGULATION (VIN = 3.6V IN PWM MODE)
FIGURE 10. SOFT-START
FIGURE 11. PFM MODE (VIN = 3V; VO = 1.6V; IO = 50mA)
5
FIGURE 12. STEADY-STATE IN PWM MODE (VIN = 3.6V;
VO = 1.6V; IO = 1A)
FN9256.0
March 7, 2006