LM34919BTLX National Semiconductor Corporation, LM34919BTLX Datasheet
LM34919BTLX
Related parts for LM34919BTLX
LM34919BTLX Summary of contents
Page 1
... Additional features include: VCC under-voltage lockout, thermal shutdown, gate drive under-voltage lockout, and maximum duty cycle limiter. Basic Step Down Regulator © 2010 National Semiconductor Corporation LM34919B Features ■ AEC-Q100 Grade 1 qualified (-40°c to 125°c) ■ ...
Page 2
... LM34919BQTLX 10–Bump micro SMD LM34919BTL 10-Bump micro SMD LM34919BTLX 10–Bump micro SMD For detailed information on micro SMD packages, refer to the Application Note AN-1112. *Automotive grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, includng defect detection methodologies. Reliability qualification is compliant with the requirements and temperature grades defined in the AEC-Q100 standard ...
Page 3
Pin Descriptions Pin Number Name A1 RON/SD On-time control and shutdown A2 RTN Circuit Ground A3 FB Feedback input from the regulated output B1 SGND Sense Ground B3 SS Softstart C1 ISEN Current sense C3 VCC Output from the startup ...
Page 4
Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN to RTN BST to RTN SW to RTN (Steady State) ESD Rating (Note 2) Human Body Model BST ...
Page 5
Symbol Parameter Threshold hysteresis Off Timer t Minimum Off-time OFF Regulation and Over-Voltage Comparators (FB Pin regulation threshold REF FB over-voltage threshold FB bias current Thermal Shutdown T Thermal shutdown temperature SD Thermal shutdown hysteresis Thermal Resistance θ ...
Page 6
Typical Performance Characteristics Efficiency at 2.1 MHz, 3.3V Efficiency at 2.1 MHz vs www.national.com 30102741 30102745 CC 30102735 6 Efficiency at 250 kHz, 3.3V 30102742 V vs 30102746 I vs. Externally Applied V ...
Page 7
ON-TIME vs. V and 30102703 Operating Current into V IN 30102744 V UVLO at Vin vs. Temperature CC 30102747 Voltage at the R /SD Pin ON Shutdown Current into V Gate Drive UVLO vs. Temperature 7 30102737 ...
Page 8
V Voltage vs. Temperature CC V Current Limit vs. Temperature CC Soft-Start Current vs. Temperature www.national.com V Output Impedance vs. Temperature CC 30102749 Reference Voltage vs. Temperature 30102751 On-Time vs. Temperature 30102753 8 30102750 30102752 30102754 ...
Page 9
Minimum Off-Time vs. Temperature Operating & Shutdown Current vs. Temperature Current Limit Threshold vs. Temperature 30102755 RON Pin Shutdown Threshold vs. Temperature 30102757 9 30102756 30102758 www.national.com ...
Page 10
Block Diagram www.national.com 10 30102701 ...
Page 11
Functional Description The LM34919B Step Down Switching Regulator features all the functions needed to implement a low cost, efficient buck bias power converter capable of supplying at least 0.6A to the load. This high voltage regulator contains an N-Channel buck ...
Page 12
The operating frequency is approximately: The buck switch duty cycle is approximately equal to: In discontinuous conduction mode current through the induc- tor ramps up from zero to a peak ...
Page 13
Regulation Comparator The feedback voltage compared to the voltage at the Softstart pin (2.5V). In normal operation (the output voltage is regulated), an on-time period is initiated when the voltage at FB falls below 2.5V. The buck ...
Page 14
N - Channel Buck Switch and Driver The LM34919B integrates an N-Channel buck switch and as- sociated floating high voltage gate driver. The peak current allowed through the buck switch is 1.5A, and the maximum allowed average current is 1A. ...
Page 15
L1: The main parameter affected by the inductor is the in- ductor current ripple amplitude (I ). The minimum load cur- OR rent is used to determine the maximum allowable ripple in order to maintain continuous conduction mode, where the ...
Page 16
FIGURE 5. Example Circuit FIGURE 6. Efficiency (Circuit of Figure 5) FIGURE 7. Frequency vs. V (Circuit of Figure 30102721 30102740 30102723 ...
Page 17
LOW OUTPUT RIPPLE CONFIGURATIONS For applications where lower ripple at V following options can be used to reduce or nearly eliminate the ripple. a) Reduced ripple configuration: In Figure 8, Cff is added across R1 to AC-couple the ripple at ...
Page 18
P = Iout (1- where Iout is the load current the diode’s forward volt- F age drop, and D is the on-time duty cycle. The power loss in the inductor is approximately: P ...
Page 19
Physical Dimensions inches (millimeters) unless otherwise noted Note 1.753 mm, ±0.030 1.987 mm, ±0.030 0.60 mm, ±0.075 mm 10 Bump micro SMD Package NS Package Number TLP10KAA 19 www.national.com ...
Page 20
... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...