3MHz Dual 1.5A Step-Down Converters and Dual
Low-Input LDOs with I
2
C Compatible Interface
ISL9305H
ISL9305H is an integrated mini Power Management IC (mini-
PMIC) for powering low-voltage microprocessor, or applications
using a single Li-Ion or Li-Polymer cell battery to power multiple
voltage rails. ISL9305H integrates two high-efficiency 3MHz
synchronous step-down converters (DCD1 and DCD2) and two
low-input, low-dropout linear regulators (LDO1 and LDO2).
The 3MHz PWM switching frequency allows the use of very
small external inductors and capacitors. Both step-down
converters can enter skip mode under light load conditions to
further improve the efficiency and maximize the battery life.
For noise sensitive applications, they can also be programmed
through I
2
C interface to operate in forced PWM mode
regardless of the load current condition. The I
2
C interface
supports on-the-fly slew rate control of the output voltage from
0.825V to 3.6V at 25mV/step size for dynamic power saving.
Each step-down converter can supply up to 1.5A load current.
The default output voltage can be set from 0.8V to VIN using
external feedback resistors on the adjustable version, or the
ISL9305H can be ordered in factory pre-set power-up default
voltages in increments of 100mV from 0.9V to 3.6V.
ISL9305H also provides two 300mA low dropout (LDO)
regulators. The input voltage range is 1.5V to 5.5V allowing them
to be powered from one of the on-chip step-down converters or
directly from the battery. The default LDO output comes with
factory pre-set fixed output voltage options between 0.9V to 3.3V.
ISL9305H is available in a 4mmx4mm 16 Ld TQFN package.
Features
• Dual 1.5A, Synchronous Step-down Converters and Dual
300mA, General-purpose LDOs
• Input Voltage Range
- DCD1/DCD2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5V to 5.5V
- LDO1/LDO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5V to 5.5V
• 400kb/s I
2
C-Bus Series Interface Transfers the Control Data
Between the Host Controller and the ISL9305H
• Adjustable Output Voltage
- DCD1/DCD2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8V to V
IN
- Fixed Output I
2
C Programmability
• At 25mV/Step . . . . . . . . . . . . . . . . . . . . . . . . . . 0.825V to 3.6V
• LDO1/LDO2 Output Voltage I
2
C Programmability
- At 50mV/Step . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9V to 3.3V
• 50μA I
Q
(Typ) with DCD1/DCD2 in Skip Mode; 20μA I
Q
(Typ)
for Each Enabled LDO
• On-the-fly I
2
C Programming of DC/DC and LDO Output
Voltages
• DCD1/DCD2 I
2
C Programmable Skip Mode Under Light
Load or Forced Fixed Switching Frequency PWM Mode
• Small, Thin 4mmx4mm TQFN Package
Applications
• Cellular Phones, Smart Phones
• PDAs, Portable Media Players, Portable Instruments
• Single Li-Ion/Li-Polymer Battery-Powered Equipment
• DSP Core Power
Related Literature
•
ISL9305 Data Sheet
•
“ISL9305IRTZEVAL1Z and ISL9305HIRTZEVAL1Z
Evaluation Boards”
PG
2.5V TO 5.5V
C
10
10µF
VINDCD1
VINDCD2
L
1
= 1.5µH
SW1
FB1
R
1
1.5A
*
R
2
C
4
10µF
1.5A
SDAT
1.5V TO 5.5V
C
2
1µF
1.5V TO 5.5V
C
3
1µF
SCLK
VINLDO1
ISL9305H
SW2
FB2
VOLDO1
L
2
= 1.5µH
R
3
*
R
4
C
5
10µF
300mA
300mA
VINLDO2
VOLDO2
C
6
1µF
C
7
1µF
GNDDCD1 GNDDCD2 GNDLDO
*ONLY FOR ADJUSTABLE OUTPUT VERSION. FOR FIXED OUTPUT VERSION, DIRECTLY
CONNECT THE FB PIN TO THE OUTPUT OF THE BUCK CONVERTER.
FIGURE 1. TYPICAL APPLICATION DIAGRAM
November 8, 2010
FN7724.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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