LM5069: LM5069MM-2/NOPB

Jonathan Pereira

Prodigy 10 points

Part Number: LM5069

These are the following requirements:

Maximum Input Voltage = 30V
Minimum Input Voltage = 10V
Maximum Load Current = 10A
Nominal Load Voltage = 24VDC

I would like the LM5069 to have an OVL of 30Vand UVL of 10V.

I would like the LM5069 to operate in a constant current mode and the Fault Response to be in Retry Mode.

How do I estimate the Maximum Output Load Capacitance: CLOAD
What is the difference between Minimum Power Limit to Ensure Vsns > 5mV (PLIM,MIN) and Target Power Limit?
Is the Target Power Limit more than the maximum power draw of the load?
Are there any TI N-MOSFETs currently in stock that meet the circuit requirements?

over 3 years ago

0 Avishek Pal over 3 years ago

TI__Mastermind 39820 points

Hi Jonathan,

Welcome to E2E and thanks for your interest on LM5069 !!! I will get back to you on Monday.

0 Avishek Pal over 3 years ago in reply to Avishek Pal

TI__Mastermind 39820 points

Hi Jonathan,

I would suggest you use the design calculator to start the LM5069 design activity. The design calculator is available at www.ti.com/.../snvr506.
This design calculator will suggest a suitable TI MOSFET. Then the supply situation of that particular MOSFET needs to be verified.

Please see the responses in the order of your queries.
1) C_LOAD is based on the downstream loads in your system. It is the summation of all the input capacitors connected at the downstream loads, such as DC-DC converters, etc.
2) Please refer this app note. https://www.ti.com/lit/an/slva673a/slva673a.pdf and let us know if there is any more query.
3) No, this target power limit is not related to the power drawn by the load. It's the power loss on the MOSFET during the startup and fault events, V_DS x I_DS.
4) As mentioned above, the design calculator will suggest a suitable TI MOSFET for your design.

Please share the filled-up design calculator for our review.

0 Jonathan Pereira over 3 years ago in reply to Avishek Pal

Prodigy 10 points

How do I estimate the Target Power Limit?

Is Plim = I_load,max X Vin,max ?

0 Avishek Pal over 3 years ago in reply to Jonathan Pereira

TI__Mastermind 39820 points

Hi Jonathon,

Targeted power limit should be just greater than the "Minimum Power Limit to Ensure Vsns > 5mV (PLIM,MIN)". Please refer to the Section 9.2.1.2.3 Select Power Limit in the datasheet.

0 Jonathan Pereira over 3 years ago in reply to Avishek Pal

Prodigy 10 points

LM5069.xlsx

I have uploaded the LM5069 Calculations. My Input supply ranges from 10V-30V. My OVL:30V and UVL:12V.
Max Load Current: 8A
I have chosen the Vishay SiJ186DP since there aren't any suitable TI mosfets in stock.

0 Jonathan Pereira over 3 years ago in reply to Jonathan Pereira

Prodigy 10 points

Are the calculations correct

0 Avishek Pal over 3 years ago in reply to Jonathan Pereira

TI__Mastermind 39820 points

Hi Jinathan,

I had two observations on the design calculator.

May I know the reason of choosing the minimum current limit as 19.4 A for the maximum load current of 8 A? The minimum current limit should be 1.1 times the maximum load current.
Following maximum values of output capacitors can be supported with the Vishay SiJ186DP.
1. 1800 μF : If can a "hot" board be hot plugged? : NO
2. 1400 μF : If can a "hot" board be hot plugged? : YES

Please see the attached modified design calculator and let me know if there is any query.

LM5069_Design_Calculator_Jonathan Pereira.xlsx

0 Jonathan Pereira over 3 years ago in reply to Avishek Pal

Prodigy 10 points

So for the modified design calculator, the circuit will be able to have a nominal output of 24V x 8A = 192W ?
In this scenario what is the wattage of Rsns?

0 Jonathan Pereira over 3 years ago in reply to Jonathan Pereira

Prodigy 10 points

I have added replacement components for D1, D2, Q1, Q2 and Z1. Please let me know if these are suitable for my circuit specifications.LM5069_v2.xlsx

0 Avishek Pal over 3 years ago in reply to Jonathan Pereira

TI__Mastermind 39820 points

Hi Jonathan,

The circuit will be able to handle a nominal output of 24V x 8A = 192W.

The power rating of the RSNS should be more than 2 W. CSS2H-3920K-5L00F or equivalent may be used.

D1, D2, Q1, Q2, and Z1 are suitable for your application.

0 Jonathan Pereira over 3 years ago in reply to Avishek Pal

Prodigy 10 points

The CSS2H-3920K-5L00F is 2mOhm. The modified design calculator sets Rsns at 5mOhm? Will any other 5mOhm >2W resistor work? Ex: CRE2512-FZ-R005E-3

0 Avishek Pal over 3 years ago in reply to Jonathan Pereira

TI__Mastermind 39820 points

CSS2H-3920K-5L00F is 5 mΩ.

Any other 5 mΩ >2W, < 1% sense resistor will work. CRE2512-FZ-R005E-3 is also fine.

0 Jonathan Pereira over 3 years ago in reply to Avishek Pal

Prodigy 10 points

Update - The Max load current has changed to 12A. I have attached the LM5069 calculator with the updated values. Can you verify if it meets the circuit specifications. LM5069_v3.xlsx

0 Avishek Pal over 3 years ago in reply to Jonathan Pereira

TI__Mastermind 39820 points

Hi Jonathan,

Two (2) MOSFETs would be required for the 12 A design to limit the maximum steady-state MOSFET junction temperature within 100 °C. Please see the attached design calculator. There were a few cells which got changed in your design calculator. I have attached the fresh one.

LM5069_Design_Calculator_Jonathan Pereira_12A_2_MOSFETs.xlsx