LM20124MH NSC [National Semiconductor], LM20124MH Datasheet
LM20124MH
Available stocks
Related parts for LM20124MH
LM20124MH Summary of contents
Page 1
LM20124 4A, 1MHz PowerWise General Description The LM20124 is a full featured 1 MHz synchronous buck reg- ulator capable of delivering continuous output current. The current mode control loop can be compensated to be stable with ...
Page 2
... Connection Diagram Ordering Information Order Number Package Type LM20124MH eTSSOP-16 LM20124MHE LM20124MHX Pin Descriptions Pin # Name 1 SS/TRK Soft-Start or Tracking control input. An internal 5 µA current source charges an external capacitor to set the Soft-Start ramp rate. If driven by a external source less than 800mV, this pin overrides the internal reference that sets the output voltage ...
Page 3
Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Voltages from the indicated pins to GND AVIN, PVIN, EN, PGOOD, SS/ TRK, COMP, FB Storage Temperature Junction Temperature ...
Page 4
Symbol Parameter Enable V EN Pin turn-on Threshold IH_EN V EN Pin Hysteresis EN_HYS Thermal Shutdown T Thermal Shutdown SD T Thermal Shutdown Hysteresis SD_HYS Thermal Resistance θ Junction to Ambient JA Note 1: Absolute Maximum Ratings indicate limits beyond ...
Page 5
Error Amplifier Gain vs. Frequency 30014236 Load Regulation 30014238 Switching Frequency vs. Temperature 30014239 Line Regulation Feedback Voltage vs. Temperature Quiescent Current vs. V (Not Switching 30014237 30014251 30014240 www.national.com ...
Page 6
Shutdown Current vs. Temperature UVLO Threshold vs. Temperature Peak Current Limit vs. V www.national.com Enable Threshold vs. Temperature 30014241 Peak Current Limit vs. Temperature 30014245 OUT 30014254 6 30014228 30014242 Peak Current Limit vs 30014255 ...
Page 7
Load Transient Response 30014234 Start-Up (Soft-Start) 30014244 Power Down 30014232 Line Transient Response Start-Up (Tracking) Short Circuit Input Current vs 30014243 30014233 IN 30014256 www.national.com ...
Page 8
P vs. I GOOD PGOOD www.national.com 30014227 8 ...
Page 9
Block Diagram 9 30014203 www.national.com ...
Page 10
Operation Description GENERAL The LM20124 switching regulator features all of the functions necessary to implement an efficient low voltage buck regula- tor using a minimum number of external components. This easy to use regulator features two integrated switches and is ...
Page 11
This feature is provided to prevent catastrophic failures from accidental device over- heating. LIGHT LOAD OPERATION The LM20124 offers increased efficiency when operating at ...
Page 12
Design Guide This section walks the designer through the steps necessary to select the external components to build a fully functional power supply. As with any DC-DC converter numerous trade- offs are possible to optimize the design for efficiency, size, ...
Page 13
Where, C (F) is the minimum required output capacitance, OUT L (H) is the value of the inductor, V DROOP voltage drop ignoring loop bandwidth considerations, ΔI (A) is the load step change, R STEP ESR capacitor ESR, V (V) ...
Page 14
To achieve a -20dB/decade slope, the error amplifier zero, located should positioned to cancel the output filter Z(EA) pole ( ...
Page 15
FIGURE 6. Sequencing LM20124 with Precision Enable The value for resistor R can be selected by the user to control B the current through the divider. Typically this resistor will be selected to be between 10 kΩ and 1 MΩ. ...
Page 16
T is the ambient temperature in ° the output load current. OUT DCR is the inductor series resistance important to always keep the operating junction temper- ature (T ) below 125°C for reliable operation. If ...
Page 17
FIGURE 10. Schematic of LM20124 Highlighting Layout Sensitive Nodes 17 30014222 www.national.com ...
Page 18
Typical Application Circuits This section provides several application solutions with a bill of materials. All bill of materials reference the below figure. Bill of Materials ( Designator Description U1 Synchronous Buck Regulator C 100 µF, 1210, ...
Page 19
Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead eTSSOP Package NS Package Number MXA16A 19 www.national.com ...
Page 20
For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators ...