MIC2155_0911 Datasheet, PDF (1/35 Pages) Micrel Semiconductor – Two-Phase, Single-Output, PWM Synchronous Buck Control IC

MIC2155/2156
Two-Phase, Single-Output, PWM
Synchronous Buck Control IC
General Description
The MIC2155 and MIC2156 are a family of two-phase,
single-output synchronous buck control ICs featuring small
size, high efficiency, and a high level of flexibility. The ICs
implement a 500kHz (MIC2155) and 300kHz (MIC2156)
voltage mode PWM control, with the outputs switching
180° out of phase. The result of the out-of-phase operation
is 1MHz (or 600kHz) input ripple with ripple current
cancellation, minimizing the required input filter
capacitance. A 1% output voltage tolerance allows the
maximum level of system performance. Internal drivers
with adaptive gate drive allow the highest efficiency with
the minimum external components.
Two independent enable pins and a power good output
are provided, allowing a high level of control and
sequencing capability.
The MIC215x family has a junction operating range from
-40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Synchronous buck control ICs with outputs switching
180° out-of-phase
• Remote sensing with internal differential amplifier
• 4.5V to 14.5V input voltage range
• Adjustable output voltages down to 0.7V
• 1% output voltage accuracy
• Starts up into a pre-biased output
• 500kHz PWM operation (MIC2155)
• 300kHz PWM operation (MIC2156)
• Adaptive gate drive allows efficiencies over 95%
• Adjustable current limit with no sense resistor
• Senses low-side MOSFET current
• Internal drivers allow 25A per phase
• Power Good output allow simple sequencing
• Dual enables with micro-power shutdown and UVLO
• Programmable soft-start pin
• Output over-voltage protection
• Works with ceramic output capacitors
• Multi-input supply capability
• Single-output high-current capability with master/slave
current sharing
• External synchronization
• Small footprint 32-pin 5mm × 5mm MLF^®
• Junction temperature range of -40°C to +125°C
Applications
• Multi-output power supplies with sequencing
• DSP, FPGA, CPU and ASIC power supplies
• DSL modems
• Telecom and networking equipment
• Servers
MLF and MicroLead Frame are registered trademarks of Amkor Technologies
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
November 2009
M9999-111209-B