LM3489_15 Datasheet, PDF (1/25 Pages) Texas Instruments – Hysteretic PFET Buck Controller With Enable Pin

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LM3489
LM3489-Q1
SNVS443B – MAY 2006 – REVISED FEBRUARY 2013
Hysteretic PFET Buck Controller With Enable Pin
Check for Samples: LM3489, LM3489-Q1
FEATURES
1
•2 Easy to use control methodology
• No control loop compensation required
• Wide 4.5V to 35V input range
• 1.239V to V_IN adjustable output range
• High efficiency 93%
• ±1.3% (±2% over temp) internal reference
• 100% duty cycle operation
• Maximum operation frequency > 1MHz
• Current limit protection
• Dedicated enable pin (on if unconnected)
• Shutdown mode draws only 7µA supply
current
• VSSOP-8
• LM3489 is AEC-Q100 Grade 1 qualified
APPLICATIONS
• Set-Top Box
• DSL or Cable Modem
• PC/IA
• Auto PC
• TFT Monitor
• Battery Powered Portable Applications
• Distributed Power Systems
• Always On Power
• High Power LED Driver
• Automotive
DESCRIPTION
The LM3489 is a high efficiency PFET switching
regulator controller that can be used to quickly and
easily develop a small, cost effective, switching buck
regulator for a wide range of applications. The
hysteretic control architecture provides for simple
design without any control loop stability concerns
using a wide variety of external components. The
PFET architecture also allows for low component
count as well as ultra-low dropout, 100% duty cycle
operation. Another benefit is high efficiency operation
at light loads without an increase in output ripple. A
dedicated Enable Pin provides a shutdown mode
drawing only 7µA. Leaving the Enable Pin
unconnected defaults to on.
Current limit protection can be implemented by
measuring the voltage across the PFET’s R_DS(ON),
thus eliminating the need for a sense resistor. A
sense resistor may be used to improve current limit
accuracy if desired. The cycle-by-cycle current limit
can be adjusted with a single resistor, ensuring safe
operation over a range of output currents.
TYPICAL APPLICATION CIRCUIT
V_IN
C_ADJ R_ADJ
Q1
+
C_IN1
C_IN2
R_IS
7
PGATE
1
ISENSE
5
ADJ
8 _VIN
3 _EN
4
LM3489
FB
2
GND
PGND
6
L
D1
C_ff
V_OUT
R1
+
C_OUT
R2
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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