Datasheet
LOW DROPOUT OPERATION 100% DUTY CYCLE
V min=V max+I maxxr max+R
I O O DS(on) L
()
ENABLE
UNDERVOLTAGE LOCKOUT
TPS62220 , , TPS62221 , , TPS62222
TPS62223 , TPS62224 , TPS62225
TPS62227 , TPS62228 , TPS62229
SLVS491E – SEPTEMBER 2003 – REVISED FEBRUARY 2009 .......................................................................................................................................
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The TPS6222x offers a low input to output voltage difference, while still maintaining operation with the 100% duty
cycle mode. In this mode, the P-channel switch is constantly turned on. This is particularly useful in
battery-powered applications to achieve longest operation time by taking full advantage of the whole battery
voltage range. The minimum input voltage to maintain regulation, depending on the load current and output
voltage, can be calculated as:
where:
• I
O, max
= maximum output current plus indicator ripple current
• r
DS(on), max
= maximum P-channel switch r
DS(on)
• R
L
= dc resistance of the inductor
• V
O, max
= normal output voltage plus maximum output voltage tolerance
Pulling the enable low forces the part into shutdown, with a shutdown quiescent current of typically 0.1 µ A. In this
mode, the P-channel switch and N-channel rectifier are turned off, the internal resistor feedback divider is
disconnected, and the whole device is in shutdown mode. If an output voltage, which could be an external
voltage source or super capacitor, is present during shutdown, the reverse leakage current is specified under
electrical characteristics. For proper operation, the enable pin must be terminated and must not be left floating.
Pulling the enable high starts up the TPS6222x with the soft start as previously described.
The undervoltage lockout circuit prevents the device from misoperation at low input voltages. It prevents the
converter from turning on the switch or rectifier MOSFET under undefined conditions.
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Product Folder Link(s): TPS62220 TPS62221 TPS62222 TPS62223 TPS62224 TPS62225 TPS62227 TPS62228
TPS62229