E910.27A Datasheet, PDF (1/50 Pages) ELMOS Semiconductor AG – External Adjustable High Efficiency PFM Step-Down Converter

- Preliminary -
E910.27A
External Adjustable High Efficiency PFM Step-Down Converter
Features
• More than 90% efficiency and 100% duty cycle
• Wide input voltage range from 5V to 40V
• Integrated 1.6A on-chip P-channel MOS power switch
• 12µA typical shutdown current
• Less than 0.5V drop voltage at 500mA output current
• 0.2V to Vinput adjustable output range
• Controllable VOUT via an external Reference
• No control loop compensation required
• Improved current-limited PFM converter
• Maximum operating frequency > 300kHz
• Power good, reset or watchdog signal
• Under-voltage lockout and thermal shutdown
• -40°C to 125°C junction temperature
• Available in thermally enhanced TSSOP24 package
Applications
• Automotive electronics
• Minimum component step-down converter
• Sequenceable POL power supply systems
• Externally controllable LED power supply
• Externally controllable power amplifier
Brief Functional Description
The easy to use hysteretic step-down converter provides high
efficiency over a wide load and input range with few external
components.
An advanced PFM control scheme gives this device the bene-
fits of a PWM converter with high efficiency at heavy loads,
while using very low operating current at light loads to maintain
an excellent behaviour over load variation.
Maximum switching frequency of 300kHz permits small exter-
nal components and operation to 100% duty cycle allows the
lowest possible dropout voltage. For optimal flexibility an exter-
nal shunt resistor sets the maximum output current.
The converter contains a selectable internal reference with
high or low voltage to regulate a wide range of output voltage
or output current. The reference for output regulation can also
be provided from an external source, like DAC.
A selectable power good, reset or watchdog signal is provided.
An external capacitor sets the reset output pulse duration and /
or watchdog trigger time.
An optional internal short delay timeout can greatly reduce the
losses of the whole application in case of short or overload.
Very low shutdown and quiescent currents and the wide input
voltage range makes the converter ideal for battery powered
systems.
Typical Application
VINPUT
CSM
DAC
ENPS
SMON, RSEL
VSM
E91027
RFB1 RFB2
CDRV
RSIN
CDR
RS
CIN
SWD
DSW
LCK
COUT
VOUTPUT
ELMOS Semiconductor AG
Specification 1 / 50
03SP0357E.00 05.09.2006