Regulator/DC-DC Converter. LM5115A Datasheet

LM5115A Converter. Datasheet pdf. Equivalent

LM5115A Datasheet
Recommendation LM5115A Datasheet
Part LM5115A
Description Secondary Side Post Regulator/DC-DC Converter
Feature LM5115A; LM5115A www.ti.com SNVS467B – DECEMBER 2006 – REVISED MARCH 2013 LM5115A Secondary Side Post Regu.
Manufacture etcTI
Datasheet
Download LM5115A Datasheet




Texas Instruments LM5115A
LM5115A
www.ti.com
SNVS467B – DECEMBER 2006 – REVISED MARCH 2013
LM5115A Secondary Side Post Regulator/DC-DC Converter with Power-up/Power-down
Tracking
Check for Samples: LM5115A
FEATURES
1
2 Power-up/Power-down Tracking
• Self-synchronization to Main Channel Output
• Leading Edge Pulse Width Modulation
• Valley Current Mode Control
• Standalone DC/DC Synchronous Buck Mode
• 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 Package
DESCRIPTION
The LM5115A controller contains all of the features
necessary to produce multiple tracking outputs using
the Secondary Side Post Regulation (SSPR)
technique. The SSPR technique develops a highly
efficient and well regulated auxiliary output from the
secondary side switching waveform of an isolated
power converter. LM5115A can be also used as a
standalone DC/DC synchronous buck controller
(Refer to Standalone DC/DC Synchronous Buck
Mode section). 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 LM5115A 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
Main
3.3V
+12V
VCC Sync HB
LM5115A
VBIAS
HO
RAMP
HS
TRK/SS
CO
LO
COMP
CS
FB VOUT
PGND AGND
RS Auxiliary
Output
2.5V
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 © 2006–2013, Texas Instruments Incorporated



Texas Instruments LM5115A
LM5115A
SNVS467B – DECEMBER 2006 – REVISED MARCH 2013
Connection Diagram
1
CS
2
VOUT
3
AGND
4
CO
5
COMP
6 FB
7
TRK/SS
8
RAMP
VBIAS 16
15
HB
14
HO
13
HS
12
VCC
11
LO
10
PGND
9
SYNC
Figure 2. 16-Lead TSSOP
See Package Numbers PW0016A
www.ti.com
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Product Folder Links: LM5115A
Copyright © 2006–2013, Texas Instruments Incorporated



Texas Instruments LM5115A
LM5115A
www.ti.com
Pin Name
1 CS
2 VOUT
3 AGND
4 CO
5 COMP
6 FB
7 TRK/SS
8 RAMP
9 SYNC
10 PGND
11 LO
12 VCC
13 HS
14 HO
15 HB
16 VBIAS
SNVS467B – DECEMBER 2006 – REVISED MARCH 2013
PIN DESCRIPTIONS
Description
Application Information
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).
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.
Analog ground
Connect directly to the power ground pin (PGND).
Current limit output
For normal current limit operation, connect the CO pin to the
COMP pin through a diode. CO pin is connected to ground through
a resistor in series with a capacitor to provide adequate control
loop compensation for the current limit gm amplifier. Leave this pin
open to disable the current limit function.
Compensation. Error amplifier output
COMP pin pull-up is provided by an internal 300uA current source.
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.
Tracking/Soft-start control
Non-inverting input to error amp with 15 µA pull-up current source.
Can be used with capacitor for soft-start or tied to external divider
of a master output for tracking. TRK/SS is the reference input to the
amplifier when the voltage applied to the pin is < 0.75V. For higher
inputs, the internal reference controls the amplifier.
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.
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 .
Power Ground
Connect directly to the analog ground pin (AGND).
Low-side gate driver output
Connect to the gate of the low-side synchronous MOSFET through
a short low inductance path.
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.
High-side MOSFET source connection
Connect to negative terminal of the bootstrap capacitor and the
source terminal of the high-side MOSFET.
High-side gate driver output
Connect to the gate of high-side MOSFET through a short low
inductance path.
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.
Supply Bias Input
Input to the LDO bias regulator and current sense amplifier that
powers internal blocks. Input range of VBIAS is 4.5V to 30V.
Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM5115A
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