SS6577 Datasheet, PDF (1/14 Pages) Silicon Standard Corp. – External NMOS Step-Down PWM Controller

SS6577
External NMOS Step-Down PWM Controller
FEATURES
N-Channel MOSFET Drive
Operating input voltage from 4.5V to 24V
Wide output Range : 0.8V to 20V
Reference: ±1.5% 0.8V Reference
Low dropout operation : 95% duty cycle
Fixed constant frequency - 500kHz
Low standby current, I _Q typically 720µA
Logic-control micropower shutdown
Output overvoltage protection
Internal diode for bootstrapped gate drive
Current-mode operation for excellent line and
load transient response
Available in 8-lead SO or MSOP packages
APPLICATIONS
LCD Monitor
Palmtop Computers, PDAs
Wireless Modems
On-Card Switching Regulators
DC Power Distribution Systems
DESCRIPTION
The SS6577 is a current-mode switching
regulator controller that drives an external
N-channel power MOSFET using a fixed fre-
quency architecture. It uses an external divider to
adjust the output voltage from 0.8V to 20V with
excellent line and load regulation. A maximum
high duty-cycle limit of 95% provides low
dropout operation which extends operating
time in battery-operated systems.
A constant switching frequency of 500KHz is
used thus allowing smaller sized filter
components. The operating current level is
user-programmable via an external current
sense resistor. It also provides output overvolt-
age protection under fault conditions.
A multifunction pin (ITH/RUN) allows external
compensation for optimum load step re-
sponse plus shutdown. Soft start can also be
implemented with this pin to properly se-
quence supplies. Packages available are
SOP-8 and MSOP-8 for SMD.
Rev.1.02 3/26/2004
www.SiliconStandard.com
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