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ADP1607 boost DCDC; Max Vin voltage is Vout?

Hi

ADP1607 datasheet say "0.8V to Vout input voltage range"

But when Vin=Vout, it doesn't work. I think.

In other colum, it need reduce diode or cascode FET voltage , I think.

"To use the ADP1607 in the VOUT = 2.5V portion of your application, you would have to reduce the maximum input voltage to 2.5V through diodes or a cascode FET."

Efficiency of ADP1607 at 32 uA

1. Minimum ON time of this device?

     I would like estimate min duty.

   (Why it doesn't have timing condition?)

2. The condition that  Vin = Vout is ok

    How comes input voltage range is to Vout?

3. If Vin = Vout is OK , why is it missing that data in Fig17?

Sorry it might   be primitive questions.

Regards

moto

  • Hi Moto,

    Thank you for all your questions and your interest in the ADP1607.

    1) ADP1607 does not operate in 100% duty cycle mode but there is no implicit minimum on time.

    2) The Max input voltage for the ADP1607 is Vout, which is characterized on the bench as the datasheet says.

    Best regards,

    Hong

  • Dear Hong

    Thank you very much for your support!

    When we use ADP1607ACPZN001 ( PWM mode) with light load, then output might be skipped, I think.

    It must be operate in Vin=Vout condition, but output might have many ripples, that you mean?

     

    And you means, this comments is NOT TRUE?  ------>Efficiency of ADP1607 at 32 uA

    “In the Specifications table for the ADP1607 it lists the VIN range as 0.8V to VOUT.

    This means that VIN can never be greater than VOUT.

    The ADP1607 does not have a pass through mode and the architecture does not support situations where VIN > VOUT.”

    Figure 17 is measuring Vin=0.8 to Vout – about 0.4V.

    It might be able to draw when output current decreased.

    Could you show the Vin=Vout data?

    It might be my misunderstanding.

    Please instruct me.

    Regards

    moto

  • Hi Moto,

    My comments are based on the individual lab test. The part works at Max input voltage = Vout and no conflict with the comments in Efficiency of ADP1607 at 32uA

    We are waiting for the design team for clarification and will update it ASAP. Thanks for your patience.

    BR,

    Hong

  • Dear Hong

    Thank you very much for your support.

    I'm waiting.

    Regards

    moto

  • Hi Moto,

    Thanks again for your patience.

    When the ADP1607ACPZN001( PWM mode) operate in low duty cycle (ie: Vin is close to Vout) and especially at light load, the internal sense circuitry doesn’t have enough time to operate properly. The output is prevented from going to high because the PWM comparator is overriding the next set edge from the internal oscillator. This causes the part to skip pulses,  therefore the output ripple is larger.

    Here is the max output current full data for VOUT=2.5V and the other voltages would continue to increase similarly to 2.5V.

    Please let us know if you need additional data.

    Best Regards,

    Hong

  • Dear Hong

     Thank you very much for the good data.

    And I'm sorry for my slow reply.

    This data shows only Vout=Vin=2.5V, but it might be possible to show the data of Vout=Vin =1.8V, I think.

    It is good if we have minimum on time data.

    But I got the operation of this device, I think.

    Thank you very much for many support.

    Regards

    moto