Features: · 300 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 TSSOPApplication· Notebook and subnotebook computers
· Wireless data terminals
· Battery-powered instrumentsPinout
Specifications
| Output Current |
20000 mA |
| Input Min Voltage |
5.5 Volt |
| Input Max Voltage |
30 Volt |
| Feedback Voltage |
2.2 Volt |
| Feedback Tolerance |
2 % |
| Frequency Min |
300 kHz |
| Frequency Max |
300 kHz |
| Efficiency (peak) |
96 % |
| Output Range |
2.2V-8.0V (each output) |
| Adj Switch Frequency |
Yes |
| Adjustable Output |
Yes |
| Synchronous Rectification |
Yes |
| On/Off Pin |
Yes |
| Error Flag |
No |
| SoftStart |
Yes |
| Sync Pin |
Yes |
| Inverting |
No |
| Flyback |
No |
| Lossless Current Sense |
No |
| RegType |
Switching Controller |
| Temperature Min |
0 deg C |
| Temperature Max |
125 deg C |
| Channels |
3 Channels |
| Special Features |
Individual softstart allows sequencing; 5V/50mA linear output; FPWM |
| Topology |
Buck |
| PWM Mode |
Current |
| Step-Down |
Yes |
| Step-Up |
No |
| Output Max |
8 Volt |
| Output Min |
2.2 Volt |
| View Using Catalog |
If Military/Aerospace specified devices are required,please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
IN, SW1, and SW2 .................................−0.3 to 31V
FB1 and FB2 ............................................−0.3 to 3V
SD, ON/OFF1, ON/OFF2,...........−0.3 to (VLIN +0.3)V
2NDFB/FPWM, SYNC, REF,
SS1, SS2, COMP1,
COMP2 and CSL1
LIN ..........................................................−0.3 to 6V
CSH1, CSH2, and CSL2 (Note 12) ...........−0.3 to 9V
Voltage from CBOOT1 to SW1..................−0.3 to 5V
and from CBOOT2 to SW2
Voltage from HDRV1 to SW..............................1-0.3V
and from HDRV2 to SW2
Voltage from CBOOT1 to..................................−0.3V
HDRV1 and from CBOOT2
HDRV2
Junction Temp............................................. +150°C
Power Dissipation (Note 3) ..........................883 mW
Ambient Storage Temp. (TJ) .............−65 to +150°C
Soldering Dwell Time, Temp. (Note 4)
Wave 4 sec, .................................................260°C
Infrared 10 sec, ............................................240°C
Vapor Phase 75 sec, ....................................219°C
ESD Rating (Note 5) ...........................................2 kV
DescriptionThe LM2641 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 300 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.
LM2641 Data Sheet
