December 21, 2005
Triple Output Regulator with Single
Synchronous Buck and Dual LDO
The ISL6455 is a highly integrated triple output regulator
which provides a single chip solution for FPGAs and wireless
chipset power management. The device integrates a high
efficiency synchronous buck regulator (adjustable) with two
ultra low noise LDO regulators (adjustable). Either the
ISL6455 or ISL6455A can be selected based on whether
3.3V ±10% or 5V ±10% is required as an input voltage.
The synchronous current mode control PWM regulator with
integrated N- and P-channel power MOSFET provides
adjustable voltages based on external resistor setting.
Synchronous rectification with internal MOSFETs is used to
achieve higher efficiency and reduced number of external
components. Operating frequency is typically 750kHz
allowing the use of smaller inductor and capacitor values.
The device can be synchronized to an external clock signal
in the range of 500kHz to 1MHz. The PG_PWM output
indicates loss of regulation on PWM output.
The ISL6455 also has two LDO adjustable regulators using
internal PMOS transistors as pass devices. LDO2 features
ultra low noise typically below 30µVRMS to aid VCO stability.
The EN_LDO pin controls LDO1 and LDO2 outputs. The
ISL6455 also integrates a RESET function, which eliminates
the need for additional RESET IC required in WLAN and
other applications. The IC asserts a RESET signal whenever
the VIN supply voltage drops below a preset threshold,
keeping it asserted for at least 25ms after VIN has risen
above the reset threshold. The PG_LDO output indicates
loss of regulation on either of the two LDO outputs. Other
features include overcurrent protection and thermal
shutdown for all the three outputs.
High integration and the thin Quad Flat No-lead (QFN)
package makes ISL6455 an ideal choice for powering
FPGAs and small form factor wireless cards such as
PCMCIA, mini-PCI and Cardbus-32.
PART NUMBER* PART
TEMP. PACKAGE PKG.
MARKING RANGE (°C) (Pb-Free) DWG. #
-40 to 85 24 Ld QFN L24.4x4B
ISL6455AIRZ 6455AIRZ -40 to 85 24 Ld QFN L24.4x4B
Add “-TK” or T5K suffix for tape and reel.
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.
• Fully integrated synchronous buck regulator + dual LDO
• PWM output voltage adjustable.
- 0.8V to 2.5V with ISL6455 (VIN = 3.3V)
- 0.8V to 3.3V with ISL6455A (VIN = 5.0V)
• High output current. . . . . . . . . . . . . . . . . . . . . . . . . 600mA
• Dual LDO adjustable options
- LDO1, 1.2V to Vin-0.3V (3.3Vmax). . . . . . . . . . . 300mA
- LDO2, 1.2V to Vin-0.3V (3.3Vmax). . . . . . . . . . . 300mA
• Ultra-compact DC/DC converter design
• Stable with small ceramic output capacitors and no load
• High conversion efficiency
• Low shutdown supply current
• Low dropout voltage for LDOs
- LDO1 . . . . . . . . . . . . . . . . . . 150mV (typical) at 300mA
- LDO2 . . . . . . . . . . . . . . . . . . 150mV (typical) at 300mA
• Low output voltage noise
- <30µVRMS (typical) for LDO2 (VCO supply)
• PG_LDO and PG_PWM (PWM and LDO) outputs
• Extensive circuit protection and monitoring features
- PWM overvoltage protection
- Overcurrent protection
- Thermal shutdown
• Integrated RESET output for microprocessor reset
• Proven reference design for total WLAN system solution
• QFN package
- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat
No Leads - Product Outline
- Near Chip-Scale package footprint Improves PCB
efficiency and is thinner in Profile
• Pb-free plus anneal available (RoHS compliant)
• WLAN cards
- PCMCIA, Cardbus32, MiniPCI cards
- Compact flash cards
• Hand-held instruments
• TB363 - Guidelines for Handling and Processing Moisture
Sensitive Surface Mount Devices (SMDs)
• TB389 - PCB Land Pattern Design and Surface Mount
Guidelines for QFN Packages
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright Intersil Americas Inc. 2005. All Rights Reserved
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