Supply Controller. LM2640 Datasheet

LM2640 Controller. Datasheet pdf. Equivalent


Part LM2640
Description Dual Adjustable Step-Down Switching Power Supply Controller
Feature LM2640 www.ti.com SNVS019B – DECEMBER 1998 – REVISED APRIL 2013 LM2640 Dual Adjustable Step-Down .
Manufacture etcTI
Datasheet
Download LM2640 Datasheet


LM2640 Dual Adjustable Step-Down Switching Power Supply Cont LM2640 Datasheet
LM2640 www.ti.com SNVS019B – DECEMBER 1998 – REVISED APRIL LM2640 Datasheet
LM26400Y Dual 2A, 500kHz Wide Input Range Buck Regulator Fe LM26400Y Datasheet
Product Folder Sample & Buy Technical Documents Tools & S LM26400Y Datasheet
Recommendation Recommendation Datasheet LM2640 Datasheet




LM2640
LM2640
www.ti.com
SNVS019B – DECEMBER 1998 – REVISED APRIL 2013
LM2640 Dual Adjustable Step-Down Switching Power Supply Controller
Check for Samples: LM2640
FEATURES
1
2 200 kHz Fixed-Frequency Switching
• Switching Synchronization with an External
Signal up to 400 kHz
• Optional Pulse-Skipping Mode
• Adjustable Secondary Feedback
• Input Undervoltage Lockout
• Output Undervoltage Shutdown Protection
• Output Overvoltage Shutdown Protection
• Programmable Soft-Start (Each Controller)
• 5V, 50 mA Linear Regulator Output
• Precision 2.5V Reference Output
• 28-Pin Package
APPLICATIONS
• Notebook and Subnotebook Computers
• Wireless Data Terminals
• Battery-Powered Instruments
KEY SPECIFICATIONS
• 96% Efficient
• 5.5V to 30V Input Range
• Dual Outputs Adjustable from 2.2V to 6V
• 0.5% Typical Load Regulation Error
• 0.002%/V Typical Line Regulation Error
DESCRIPTION
The LM2640 is a dual step-down power supply
controller intended for application in notebook
personal computers and other battery-powered
equipment.
Fixed-frequency synchronous drive of logic-level N-
channel power MOSFETs is combined with an
optional pulse-skipping mode to achieve ultra efficient
power conversion over a 1000:1 load current range.
The pulse-skipping mode can be disabled in favor of
fixed-frequency operation regardless of the load
current level.
High DC gain and current-mode feedback control
assure excellent line and load regulation and a wide
loop bandwidth for fast response to dynamic loads.
An internal oscillator fixes the switching frequency at
200 kHz. Optionally, switching can be synchronized
to an external clock running as fast as 400 kHz.
An optional soft-start feature limits current surges
from the input power supply at start up and provides
a simple means of start-up sequencing.
Logic-level inputs allow the controllers to be turned
ON and OFF separately.
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 © 1998–2013, Texas Instruments Incorporated



LM2640
LM2640
SNVS019B – DECEMBER 1998 – REVISED APRIL 2013
Connection Diagram
www.ti.com
Pin #
1
Name
CSH2
2 FB2
3 COMP2
4 SS2
5 ON/OFF2
6 SD
7 SYNC
8 GND
9 REF
10 2NDFB/FPWM
11 ON/OFF1
12 SS1
13 COMP1
14 FB1
15 CSH1
16 HDRV1
17 SW1
18 CBOOT1
19 LDRV1
20 PGND
Figure 1. 28-Lead TSSOP (PW) Package
Top View
See Package Number PW0028A
Pin Description(1)
Function
The sense point for the positive side of the voltage across the current sense resistor (R13) placed in
series with output #2.
The regulated output voltage appearing at output #2 is sensed using this pin by connecting it to the
center of the output resistive divider (R15 and R16).
An R-C network made up of R11, C10, and C12 is connected to this pin which provides loop
compensation for regulated output #2.
This provides programmable soft-start for the #2 output along with capacitor C15.
This pin turns off only output #2.
The part can be put into “sleep” mode using this pin, where both outputs are off and the internal chip
functions are shut down.
The internal oscillator may be synchronized to an external clock via this pin.
Connect this pin to circuit Signal Ground.
Internal 2.5V reference voltage. This voltage is turned off by the SD pin, but remains on if either or both
ON/OFF pins are pulled low, which turns off the regulated output(s).
A 12V supply can be generated using an auxiliary winding on the 5V output inductor. Feedback to
control this 12V output is brought in through this pin. If the 12V supply is not required, this pin can also
force the chip to operate at fixed frequency at light loads by pulling the pin low (this is the “forced-PWM”
mode of operation). This will prevent the converter from operating in pulse-skipping mode.
This pin turns off only output #1.
This provides programmable soft-start for the #1 output along with capacitor C3.
An R-C network made up of R6, C5, and C7 is connected to this pin which provides loop compensation
for regulated output #1.
The regulated output voltage appearing at output #1 is sensed using this pin by connecting it to the
center of the output resistive divider (R1 and R2).
The sense point for the positive side of the voltage across the current sense resistor (R4) placed in
series with output #1.
The drive for the gate of the high-side switching FET used for output #1.
This is the switching output drive point of the two power FETs which produce output #1.
The bootstrap capacitor (C8) for output #1 is returned to this point.
The drive for the gate of the low-side switching FET (synchronous rectifier) used for output #1.
Connect this pin to circuit Power Ground.
(1) (Refer to Typical Application Circuits)
2 Submit Documentation Feedback
Product Folder Links: LM2640
Copyright © 1998–2013, Texas Instruments Incorporated







@ 2014 :: Datasheetspdf.com :: Semiconductors datasheet search & download site (Privacy Policy & Contact)