LM51031D HTC [HTC Korea TAEJIN Technology Co.], LM51031D Datasheet

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LM51031D

Manufacturer Part Number
LM51031D
Description
Fast PFET Buck Controller
Manufacturer
HTC [HTC Korea TAEJIN Technology Co.]
Datasheet
2008 - Ver. 1.0
The LM51031 is a switching contoller for use in DC-DC converters.
It can be used in the buck topology with a minimum number of
external components. The LM51031 consists of a Vcc monitor for
controlling the state of the device, 1.0A power driver for controlling
the gate of a discrete P-Channel transistor, fixed frequency oscillator,
short circuit protection timer, programmable Soft-Start, precision
reference, fast output voltage monitoring comparator, and output
stage driver logic with latch.
The high frequency oscillator allows the use of small inductiors
and output capacitors, minimizing PC board area and system cost.
The programmable Soft-Start reduces current surges at startup. The
short circuit protection timer signifaicantly reduces the duth cycle to
approximately 1/30 of its cycle during short circuit conditions.
Fast PFET Buck Controller
FEATURES
DESCRIPTION
Typical Application (Fixed Output Voltage Versions)
1.0 A Totem Pole Output Driver
High Speed Oscillator (700 kHz max)
No Stability Compensation Required
Lossless Short Circuit Protection
Vcc Monitor
2.0% Precision Reference
Programmable Soft-Start
Moisture Sensitivity Level 3
Figure 1. Block Diagram and Typical Application
− 1 −
ORDERING INFORMATION
LM51031D LM51031
Device
SOP-8 PKG
Marking
LM51031
Package
SOP-8
HTC

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LM51031D Summary of contents

Page 1

... Typical Application (Fixed Output Voltage Versions) Figure 1. Block Diagram and Typical Application 2008 - Ver. 1.0 ORDERING INFORMATION Device LM51031D LM51031 − 1 − LM51031 SOP-8 PKG Marking Package SOP-8 ...

Page 2

Fast PFET Buck Controller MAXIMUM RATINGS (Absolute Maximum Ratings indicate limits beyond which damage to the device may occur) Rating Maximum Supply Voltage Driver Supply Voltage Driver Output Voltage C , CS, V (Logic Pin) OSC FB Peak Output Current ...

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Fast PFET Buck Controller ELECTRICAL CHARACTERISTICS (Specifications apply for 4.5V ≤ V Characteristic Oscillator Frequency Charge Current Discharge Current Maximum Duty Cycle Short Circuit Timer Charge Current Fast Discharge Current Slow Discharge Current Start Fault Inhibit Time Valid Fault Time ...

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Fast PFET Buck Controller THEORY OF OPERATION Control Scheme The LM51031 monitors and the output voltage to determine when to turn on the PFET below the internal reference voltage of 1.25V during theoscillator’s charge cycle, the PFET is ...

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Fast PFET Buck Controller the PFET off and V continue to rise, the CC C oscillator capacitor (C ) and Soft start/Fault OSC Timing capacitor(CS) charges via internal current sources. C gets charged by the current source OSC ...

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Fast PFET Buck Controller Buck Regulator Operation A block diagram of a typical buck regulator is shown in Figure assume that the output transistor is initially off, and the system is in discontinuous operation, the inductor current ...

Page 7

Fast PFET Buck Controller 2) Switching Frequency and On and Off Time Calculations Given that f = 200 kHz and Oscillator Capacitor Selection The switching frequency is set by COSC, whose value is given by: 4) Inductor ...

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Fast PFET Buck Controller 7) Divider Bypass Capacitor CRR Since the feedback resistors divide the output voltage by a factor of 4.0, i.e. 5.0 V/1. 4.0, it follows that the output ripple is also divided by four. This ...

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Fast PFET Buck Controller A P−Ch FET with a continuous drain current (ID) rating greater than the maximum output current is required. The Gate−to−Source voltage VGS and Source Breakdown Voltage should be chosen based on the input supply voltage. The ...

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