LM27213 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Single Phase Hysteretic Buck Controller

February 2006
LM27213
Single Phase Hysteretic Buck Controller
General Description
The LM27213 is a single-phase synchronous buck regulator
controller designed to fully support a portable microproces-
sor. On-chip gate drive makes for a compact, single chip
solution. Output currents in excess of 25 Amps are possible.
The IC employs a current mode hysteretic control mecha-
nism. Inductor current is sensed through a low value sense
resistor.
The LM27213 will operate over an input voltage range of 5V
to 30V. The output voltage is programmed through 6 Voltage
Identification (VID) pins and ranges from 0.700V to 1.708V in
64 steps.
Since the error in the output voltage directly sets the inductor
current, the dynamic response to a large, fast load transient
is close to a square wave. This is optimal for mode transition
requirements. Also, due to the intrinsic input voltage feedfor-
ward characteristic of hysteretic control, the line transient
response is excellent as well.
The IC provides cycle-by-cycle peak current limit, over-
voltage protection, and a power good signal. The LM27213
fully supports the Stop CPU and Sleep modes offered by
some processors. When enabled, the IC enters a power-
saving “diode emulator” mode which helps prolong battery
runtime for portable systems.
The LM27213 also has a soft start feature for the external
adjustment of soft start speed.
Features
n Ideal load and line transient responses
n 5V to 30V input range
n On-chip gate drive
n Convenient CLK_EN# signal
n Input under-voltage lockout
n High light-load efficiency
n Adjustable analog soft start
n Peak current limit
n Over-voltage protection
n Error correction for good static accuracy
n ±1% DAC accurcy over temperature
n Interfaces with the LM2647 system supply
n Available in TSSOP or tiny LLP package
Applications
n Core voltage supply for Low Power Processors
n Low voltage high current buck regulators
Benefits
n Single chip core power solution
n Minimum output capacitance required
n Low cost, compact design
Typical Application
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