Buck Controller. LM5115 Datasheet

LM5115 Controller. Datasheet pdf. Equivalent

Part LM5115
Description Secondary Side Post Regulator / Synchronous Buck Controller
Feature LM5115 www.ti.com SNVS343E – MARCH 2005 – REVISED MARCH 2013 LM5115 Secondary Side Post Regulator.
Manufacture etcTI
Datasheet
Download LM5115 Datasheet



LM5115
LM5115
www.ti.com
SNVS343E – MARCH 2005 – REVISED MARCH 2013
LM5115 Secondary Side Post Regulator / Synchronous Buck Controller
Check for Samples: LM5115
FEATURES
1
2 Self-Synchronization to Main Channel Output
• Standalone DC/DC Synchronous Buck Mode
• Leading Edge Pulse Width Modulation
• Voltage-Mode Control with Current Injection
and Input Line Feed-Forward
• Operates from AC or DC Input up to 75V
• Wide 4.5V to 30V Bias Supply Range
• Wide 0.75V to 13.5V Output Range.
• Top and Bottom Gate Drivers Sink 2.5A Peak
• Adaptive Gate Driver Dead-Time Control
• Wide Bandwidth Error Amplifier (4MHz)
• Programmable Soft-Start
• Thermal Shutdown Protection
• TSSOP-16 or Thermally Enhanced WSON-16
Packages
DESCRIPTION
The LM5115 is a versatile switching regulator
controller. It has two main application configurations.
The first is utilizing the Secondary Side Post
Regulation (SSPR) technique to implement multiple
output power converters. In the second configuration,
it can be used as a standalone synchronous buck
controller (Please see Standalone DC/DC
Synchronous Buck Mode for more details). The
SSPR technique develops a highly efficient and well
regulated auxiliary output from the secondary side
switching waveform of an isolated power converter.
Regulation of the auxiliary output voltage is achieved
by leading edge pulse width modulation (PWM) of the
main channel duty cycle. Leading edge modulation is
compatible with either current mode or voltage mode
control of the main output. The LM5115 drives
external high side and low side NMOS power
switches configured as a synchronous buck regulator.
A current sense amplifier provides overload
protection and operates over a wide common mode
input range. Additional features include a low dropout
(LDO) bias regulator, error amplifier, precision
reference, adaptive dead time control of the gate
signals and thermal shutdown.
Typical Application Circuit
INPUT
FEEDBACK
Main Converter
PWM Controller
Phase Signal
Main
Output
3.3V
+12V
VCC Sync HB
LM5115
VBIAS
HO
RAMP
HS
SS LO
CO
COMP
CS
FB VOUT
PGND AGND
RS Auxiliary
Output
2.0V
Figure 1. Simplified Multiple Output Power Converter Utilizing SSPR Technique
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
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.
Copyright © 2005–2013, Texas Instruments Incorporated



LM5115
LM5115
SNVS343E – MARCH 2005 – REVISED MARCH 2013
Connection Diagram
1
CS
2
VOUT
3
AGND
4
CO
5
COMP
6 FB
7
SS
8 RAMP
VBIAS 16
15
HB
14
HO
13
HS
12
VCC
11
LO
10
PGND
9
SYNC
www.ti.com
CS 1
16 VBIAS
VOUT 2
15 HB
AGND 3
14 HO
CO 4
COMP 5
EP
13 HS
12 VCC
FB 6
11 LO
SS 7
10 PGND
RAMP 8
9 SYNC
Figure 3. 16-Lead WSON
Package Numbers NHQ0016A
Figure 2. 16-Lead TSSOP
Package Numbers PW0016A
Pin Descriptions
Pin Name
Description
Application Information
1
CS Current Sense amplifier positive input
A low inductance current sense resistor is connected between CS
and VOUT. Current limiting occurs when the differential voltage
between CS and VOUT exceeds 45mV (typical).
2 VOUT Current sense amplifier negative input Connected directly to the output voltage. The current sense
amplifier operates over a voltage range from 0V to 13.5V at the
VOUT pin.
3 AGND Analog ground
Connect directly to the power ground pin (PGND).
4 CO Current limit output
For normal current limit operation, connect the CO pin to the
COMP pin. Leave this pin open to disable the current limit function.
5 COMP Compensation. Error amplifier output
COMP pin pull-up is provided by an internal 300uA current source.
6
FB
Feedback. Error amplifier inverting input
Connected to the regulated output through the feedback resistor
divider and compensation components. The non-inverting input of
the error amplifier is internally connected to the SS pin.
7 SS Soft-start control
An external capacitor and the equivalent impedance of an internal
resistor divider connected to the bandgap voltage reference set the
soft-start time. The steady state operating voltage of the SS pin
equal to 0.75V (typical).
8 RAMP PWM Ramp signal
An external capacitor connected to this pin sets the ramp slope for
the voltage mode PWM. The RAMP capacitor is charged with a
current that is proportional to current into the SYNC pin. The
capacitor is discharged at the end of every cycle by an internal
MOSFET.
9 SYNC Synchronization input
A low impedance current input pin. The current into this pin sets the
RAMP capacitor charge current and the frequency of an internal
oscillator that provides a clock for the free-run (DC input) mode .
10 PGND Power Ground
Connect directly to the analog ground pin (AGND).
11 LO Low side gate driver output
Connect to the gate of the low side synchronous MOSFET through
a short low inductance path.
12
VCC
Output of bias regulator
Nominal 7V output from the internal LDO bias regulator. Locally
decouple to PGND using a low ESR/ESL capacitor located as
close to controller as possible.
13
HS High side MOSFET source connection
Connect to negative terminal of the bootstrap capacitor and the
source terminal of the high side MOSFET.
14 HO High side gate driver output
Connect to the gate of high side MOSFET through a short low
inductance path.
15 HB High side gate driver bootstrap rail
Connect to the cathode of the bootstrap diode and the positive
terminal of the bootstrap capacitor. The bootstrap capacitor
supplies current to charge the high side MOSFET gate and should
be placed as close to controller as possible.
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Product Folder Links: LM5115
Copyright © 2005–2013, Texas Instruments Incorporated





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