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ZTX455 charts interpretation — Parallax Forums

ZTX455 charts interpretation

ArchiverArchiver Posts: 46,084
edited 2000-03-19 03:44 in General Discussion
Hello all:

Can anyone tell me how to interpret the ZTX455 data sheets?

I don't see any graph for Ib vs output current, I want to know how much
current I can reliably get outta the 455 given 5mA at 5v for Ib.

I'm driving a 12v relay.

Thanks,

Mark

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-03-19 02:00
    Mark:
    I just took a quick look at the Zetex site data sheets. They sure give
    minimal data, but enough to use the devices. The normalized hfe vs Ic curve
    shows the device optimized up to 100 ma, still pretty good at 200 ma. For
    good saturation, (Vce<0.3 V), it looks like you should use an hfe of 10.
    With 5 ma base drive, you could get 10 x 5ma, or 50ma. They also claim
    minimum hfe of 30 at 200 ma with Vce=1V. This means that if you want to
    tolerate more power dissipation with Vce=1V, you could achieve 30 x 5 ma=150
    ma Ic. This would be OK because 1V x 150 ma=150 mw dissipation, and the
    device is rated 1 watt (max) at 25 deg C. If your ambient is much higher
    than this, you have to derate the max power.

    The Vbe vs Ic curve indicates you need ~0.8 Vbe at 100-200 ma. So
    5V-0.8V=4.2 V across the base resistor. The base resistor is then
    4.2/.005=840 ohms for 5 ma base drive. I would pick an 820 ohm standard
    value.

    *** BOTTOM LINE ***
    If you have 5 ma available for base drive:

    Up to 150 ma Ic.
    Use 820 ohm base to stamp pin (or whatever at 5V).

    Ray McArthur

    Original Message
    From: techno_masai <plunkettm@e...>
    To: <basicstamps@egroups.com>
    Sent: Saturday, March 18, 2000 7:43 PM
    Subject: [noparse][[/noparse]basicstamps] ZTX455 charts interpretation


    > Hello all:
    >
    > Can anyone tell me how to interpret the ZTX455 data sheets?
    >
    > I don't see any graph for Ib vs output current, I want to know how much
    > current I can reliably get outta the 455 given 5mA at 5v for Ib.
    >
    > I'm driving a 12v relay.
    >
    > Thanks,
    >
    > Mark
    >
    >
    >
    >
    > eGroups.com home: http://www.egroups.com/group/basicstamps
    > http://www.egroups.com - Simplifying group communications
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-03-19 03:02
    Hi Ray:

    Thanks for the detailed explanation, after looking at it a while, is that
    Vce 1 or 10? The chart I got just has Vce 10, anyway the fog is beginning to
    clear, #8^]

    Actually, I got the 5mA from an Omron EE-SX1070 photo interrupter, I'm using
    a 100 ohm on the emitter side and its running a little warm*, but I saw 100
    ohm in the data sheet for this thing, and a 220 ohm on the detector side,
    all 5 volt, I'll be getting the BS2 in later for a delay timer, right now I
    just want to get the relay to work from the photo interrupter.


    *Typically, how warm is warm, is warm to touch acceptable most of the time?

    Thanks,

    Mark
    Original Message
    From: rjmca <rjmca@w...>
    To: basicstamps@egroups.com <basicstamps@egroups.com>
    Date: Saturday, March 18, 2000 5:59 PM
    Subject: [noparse][[/noparse]basicstamps] Re: ZTX455 charts interpretation


    >Mark:
    >I just took a quick look at the Zetex site data sheets. They sure give
    >minimal data, but enough to use the devices. The normalized hfe vs Ic
    curve
    >shows the device optimized up to 100 ma, still pretty good at 200 ma. For
    >good saturation, (Vce<0.3 V), it looks like you should use an hfe of 10.
    >With 5 ma base drive, you could get 10 x 5ma, or 50ma. They also claim
    >minimum hfe of 30 at 200 ma with Vce=1V. This means that if you want to
    >tolerate more power dissipation with Vce=1V, you could achieve 30 x 5
    ma=150
    >ma Ic. This would be OK because 1V x 150 ma=150 mw dissipation, and the
    >device is rated 1 watt (max) at 25 deg C. If your ambient is much higher
    >than this, you have to derate the max power.
    >
    >The Vbe vs Ic curve indicates you need ~0.8 Vbe at 100-200 ma. So
    >5V-0.8V=4.2 V across the base resistor. The base resistor is then
    >4.2/.005=840 ohms for 5 ma base drive. I would pick an 820 ohm standard
    >value.
    >
    >*** BOTTOM LINE ***
    >If you have 5 ma available for base drive:
    >
    >Up to 150 ma Ic.
    >Use 820 ohm base to stamp pin (or whatever at 5V).
    >
    >Ray McArthur
    >
    >
    >
    Original Message
    >From: techno_masai <plunkettm@e...>
    >To: <basicstamps@egroups.com>
    >Sent: Saturday, March 18, 2000 7:43 PM
    >Subject: [noparse][[/noparse]basicstamps] ZTX455 charts interpretation
    >
    >
    >> Hello all:
    >>
    >> Can anyone tell me how to interpret the ZTX455 data sheets?
    >>
    >> I don't see any graph for Ib vs output current, I want to know how much
    >> current I can reliably get outta the 455 given 5mA at 5v for Ib.
    >>
    >> I'm driving a 12v relay.
    >>
    >> Thanks,
    >>
    >> Mark
    >>
    >>
    >>
    >>
    >> eGroups.com home: http://www.egroups.com/group/basicstamps
    >> http://www.egroups.com - Simplifying group communications
    >>
    >>
    >>
    >>
    >
    >
    >
    >
    >eGroups.com home: http://www.egroups.com/group/basicstamps
    >http://www.egroups.com - Simplifying group communications
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-03-19 03:44
    Maybe the Zetex site is better than your data sheet. They are
    www.zetex.com. They quote hfe at both 1V and 10V, but you want the device
    at 1V or less for good turn-on. I am not familiar with the Omron
    interrupter, but if the ZTX455 is switching your relay OK, I wouldn't worry
    about the warm device. It has a rated Tj max of 200 deg C. As you know,
    water boils at 100 deg C! The data sheet did not quote thermal resistance,
    but I bet the device can safely run too hot to hold.

    If you have a meter and are curious, you can get a good idea of the power
    dissipated by multiplying Vce x Ic. Measure across C-E for Vce, relay on.
    Measure the coil resistance out of circuit, and relay-on voltage when pulled
    in. Then Ic=relay volts/coil ohms.

    Ray
    Original Message
    From: techno_masai <plunkettm@e...>
    To: <basicstamps@egroups.com>
    Sent: Saturday, March 18, 2000 10:02 PM
    Subject: [noparse][[/noparse]basicstamps] Re: ZTX455 charts interpretation


    > Hi Ray:
    >
    > Thanks for the detailed explanation, after looking at it a while, is that
    > Vce 1 or 10? The chart I got just has Vce 10, anyway the fog is beginning
    to
    > clear, #8^]
    >
    > Actually, I got the 5mA from an Omron EE-SX1070 photo interrupter, I'm
    using
    > a 100 ohm on the emitter side and its running a little warm*, but I saw
    100
    > ohm in the data sheet for this thing, and a 220 ohm on the detector side,
    > all 5 volt, I'll be getting the BS2 in later for a delay timer, right now
    I
    > just want to get the relay to work from the photo interrupter.
    >
    >
    > *Typically, how warm is warm, is warm to touch acceptable most of the
    time?
    >
    > Thanks,
    >
    > Mark
    >
    >
    Original Message
    > From: rjmca <rjmca@w...>
    > To: basicstamps@egroups.com <basicstamps@egroups.com>
    > Date: Saturday, March 18, 2000 5:59 PM
    > Subject: [noparse][[/noparse]basicstamps] Re: ZTX455 charts interpretation
    >
    >
    > >Mark:
    > >I just took a quick look at the Zetex site data sheets. They sure give
    > >minimal data, but enough to use the devices. The normalized hfe vs Ic
    > curve
    > >shows the device optimized up to 100 ma, still pretty good at 200 ma.
    For
    > >good saturation, (Vce<0.3 V), it looks like you should use an hfe of 10.
    > >With 5 ma base drive, you could get 10 x 5ma, or 50ma. They also claim
    > >minimum hfe of 30 at 200 ma with Vce=1V. This means that if you want to
    > >tolerate more power dissipation with Vce=1V, you could achieve 30 x 5
    > ma=150
    > >ma Ic. This would be OK because 1V x 150 ma=150 mw dissipation, and the
    > >device is rated 1 watt (max) at 25 deg C. If your ambient is much higher
    > >than this, you have to derate the max power.
    > >
    > >The Vbe vs Ic curve indicates you need ~0.8 Vbe at 100-200 ma. So
    > >5V-0.8V=4.2 V across the base resistor. The base resistor is then
    > >4.2/.005=840 ohms for 5 ma base drive. I would pick an 820 ohm standard
    > >value.
    > >
    > >*** BOTTOM LINE ***
    > >If you have 5 ma available for base drive:
    > >
    > >Up to 150 ma Ic.
    > >Use 820 ohm base to stamp pin (or whatever at 5V).
    > >
    > >Ray McArthur
    > >
    > >
    > >
    Original Message
    > >From: techno_masai <plunkettm@e...>
    > >To: <basicstamps@egroups.com>
    > >Sent: Saturday, March 18, 2000 7:43 PM
    > >Subject: [noparse][[/noparse]basicstamps] ZTX455 charts interpretation
    > >
    > >
    > >> Hello all:
    > >>
    > >> Can anyone tell me how to interpret the ZTX455 data sheets?
    > >>
    > >> I don't see any graph for Ib vs output current, I want to know how much
    > >> current I can reliably get outta the 455 given 5mA at 5v for Ib.
    > >>
    > >> I'm driving a 12v relay.
    > >>
    > >> Thanks,
    > >>
    > >> Mark
    > >>
    > >>
    >
    >>
    > >>
    > >> eGroups.com home: http://www.egroups.com/group/basicstamps
    > >> http://www.egroups.com - Simplifying group communications
    > >>
    > >>
    > >>
    > >>
    > >
    > >
    > >
    > >
    > >eGroups.com home: http://www.egroups.com/group/basicstamps
    > >http://www.egroups.com - Simplifying group communications
    > >
    > >
    > >
    > >
    > >
    >
    >
    >
    > eGroups.com Home: http://www.egroups.com/group/basicstamps/
    > http://www.egroups.com - Simplifying group communications
    >
    >
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