IR2153D

[Cirkit]

I am trying to test a SMPS controller daughterboard from a compact PA system.

The daughterboard is based around an IR2153D IC. I have removed the daughterboard from the main PCB and am attempting to test it in isolation.

I have applied between 10-20V between Vcc and COM but do not see any waveform appear on HO or LO? Should the IC just produce a waveform at a frequency determined by RT and CT or do I need to connect other pins?

 

[73's de Edd]

Sir Cirkit . . . . .

It certainly appears that you need to see EXACTLY what circuitry is being upon that daughter board, as just one component might be remoted and therefore inhibit the daughter board from being able to initiate a " run by itself " pulse outputting capability.

Also, since you submitted no documentation, we can assume that you are working " naked" . . . . . being without its schematic.
Therefore, initially, is this " mobile " unit being battery powered , or is it AC plug in to get the typical HUNDREDS of volts raw DC power for the secondary POWER MOSFETS being driven ?

Some help is coming to you in the form of this referencing, in its manner of supplying multiple schematics of that device in use. Compare them to your devices circuitry JUST being used on the daughter board, to see if you might have something being left out of circuit . . . . thus inhibiting your being able to get Ho and Lo drives. ( Hee Hee HEE . . . . that " HO' " drive " it just don't sound right to me " no . . . . " That just don't sound right to me " . . . . . a la Red Skeltons . . . JUNIOR the mean widdle kid. *****)


In one situation, I can see need of the remoted optical isolators, being connected back into the daughter board.

WEFERENCING . . . . .

https://www.google.com/search?newwi...&ved=0ahUKEwjGqZPbltbjAhXGQs0KHb5XDGEQ4dUDCAo


73's de Edd . . . . .


Don't ever be so open-minded, that your brains fall out.

*****

 

[Cirkit]

Thanks for your reply 73's de Edd.

Looking at the datasheet, it seems to be similar to a 555. The IC should oscillate and produce a waveform on the LO output with just RT and CT connected. Should I therefore, assume it's faulty?

 

[Alec_t]

From P2 of the datasheet:
"Note 1: This IC contains a zener clamp structure between the chip V CC and COM which has a nominal breakdown
voltage of 15.6V. Please note that this supply pin should not be driven by a DC, low impedance power source
greater than the V CLAMP specified in the Electrical Characteristics section."
If you used a Vcc of >15.6V with no current limiting you probably fried the IC .

 

[Cirkit]

If you used a Vcc of >15.6V with no current limiting you probably fried the IC .

I applied a current limit on the power supply and monitored the current draw as I was increasing the voltage beyond 15V.

Am I right in assuming that there should be a waveform on LO when applying power between Vcc and COM?

 

[Alec_t]

There should be, unless (a) the supply voltage is below the undervoltage lockout level or (b) the oscillator section is disabled by the timing cap voltage being clamped low.
Does the cap have a disabling FET across it (as per the front page of the datasheet)?

 

[Cirkit]

There should be, unless (a) the supply voltage is below the undervoltage lockout level or (b) the oscillator section is disabled by the timing cap voltage being clamped low.
Does the cap have a disabling FET across it (as per the front page of the datasheet)?

Thanks for the pointer Alec_t, I totally overlooked the transistor mentioned in the datasheet across the timing cap! There is a G1 transistor across it with other discrete associated circuitry. I assume the transistor is an NPN with the collector connected to the CT pin and emitter to ground. When I apply power though, the transistor doesn't seem to be conducting so there should be a waveform on the output?

 

[73's de Edd]

All of the G1 marking code variants seem to be NPN's.

https://www.sphere.bc.ca/download/smd-codebook.pdf

PLUS, unless it is activated to clamp the C-E and its tied in IC circuitry to ground, it should be transparent to the IC's operationality.

I was questioning if some circuitry related to the output of the secondary of the power supply associated with an optical coupler might be on that daughter board.

The absolute most helpfull thing for evaluation, would be that you submit good close ups of both sides of the daughter board, so that could be analyzed.
Additionally, don't you think that the BRAND and MODEL of the WHOLE porta PA unit in question might ALSO be helpful ?