Totem pole driver with cross conduction protection and default low impedance state output
First Claim
1. A totem pole driver comprising:
- means for receiving a switching signal from a comparator;
means for receiving a sync signal known to lead the switching signal;
top and bottom output transistors arranged in a totem pole to provide an output from between said top and bottom output transistors;
a first circuit path, coupled to said means for receiving a switching signal, for switching said bottom output transistor on or off in response to the switching signal;
a second circuit path, slower than said first circuit path, coupled to said means for receiving a switching signal, for switching said top output transistor on in response to the switching signal after said bottom output transistor is switched off; and
a third circuit path, coupled to said means for receiving the sync signal, for switching said top output transistor off in response to the sync signal before the switching signal causes said bottom output transistor to turn on via said first circuit path.
14 Assignments
0 Petitions
Accused Products
Abstract
A totem pole driver with cross conductive protection and default low impedance state output employs a totem pole output formed by top and bottom output transistors. A first circuit path switches the bottom output transistor on or off in response to a switching signal. A second circuit path, slower than the first circuit path, switches the top output transistor on in response to the switching signal after the bottom output transistor is switched off. A third circuit path switches the top output transistor off in response to a sync signal known to lead the switching signal. An emergency voltage supply is made available to hold the bottom output transistor on and the top output transistor off if the regulated circuit voltage is lost.
37 Citations
26 Claims
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1. A totem pole driver comprising:
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means for receiving a switching signal from a comparator; means for receiving a sync signal known to lead the switching signal; top and bottom output transistors arranged in a totem pole to provide an output from between said top and bottom output transistors; a first circuit path, coupled to said means for receiving a switching signal, for switching said bottom output transistor on or off in response to the switching signal; a second circuit path, slower than said first circuit path, coupled to said means for receiving a switching signal, for switching said top output transistor on in response to the switching signal after said bottom output transistor is switched off; and a third circuit path, coupled to said means for receiving the sync signal, for switching said top output transistor off in response to the sync signal before the switching signal causes said bottom output transistor to turn on via said first circuit path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A fail safe totem pole driver comprising:
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Vreg means for carrying a regulated circuit voltage; top and bottom output transistors arranged in a totem pole to provide an output from between said top and bottom output transistors; a first transistor coupled between said regulated circuit voltage and a base of said bottom output transistor for providing current to the base of said bottom output transistor; means for switching said first transistor; a supplier of base drive current connected to the base of said top output transistor; a second transistor having a base coupled to said regulated circuit voltage, a collector coupled to said supplier of base drive current and an emitter connected to ground; and an emergency voltage supply coupled to said first transistor and to said second transistor for holding said first transistor and said second transistor on if the regulated circuit voltage is lost so that said first transistor holds said bottom output transistor on and said second transistor holds said top output transistor off. - View Dependent Claims (12, 13, 14, 15)
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16. A totem pole driver comprising:
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means for receiving a switching signal from a comparator; means for receiving a sync signal known to lead the switching signal; top and bottom output transistors arranged in a totem pole to provide an output from between said top and bottom output transistors; a supplier of base drive current to the base of said top output transistor, said base drive current supplier being coupled to said means for receiving the sync signal such that said base drive current supplier is switched off by the sync signal to switch off said top output transistor before said bottom output transistor is switched on in response to the switching signal; a bottom switch transistor, having a base coupled to said means for receiving the switching signal, a collector coupled to the base of said bottom output transistor and an emitter connected to ground, such that said bottom output transistor is held off when said bottom switch transistor is held on by the switching signal; a delay component coupled to the switching signal; a top switch transistor, having a base coupled to said delay component, a collector connected to said base drive current supplier and an emitter connected to ground so that said top output transistor is held off when said top switch transistor is on and said top output transistor is switched on when said top switch transistor is switched off by said delay component in response to the switching signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A pulse width modulator comprising:
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a capacitor; a comparator for comparing a voltage on said capacitor to a reference voltage for generating a switching signal; means for receiving a sync signal for alternately enabling charging and discharging of said capacitor; top and bottom output transistors arranged in a totem pole to provide an output from between said top and bottom output transistors; a first circuit path for switching said bottom output transistor on or off in response to the switching signal; a second circuit path, slower than said first circuit path, for switching said top output transistor on in response to the switching signal after said bottom output transistor is switched off; and a third circuit path, coupled to said means for receiving the sync signal, for switching said top output transistor off when the sync signal enables discharging of said capacitor and wherein the switching signal thereafter causes said bottom output transistor to turn on via said first circuit path.
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Specification