Datasheet

APPLICATION INFORMATION
FUNCTIONAL BLOCK DIAGRAM
VIN
UVLO
ENABLE
Thermal
Protection
Reference
Overcurrent
GateDrive
Oscillator
Ramp
Generator
VREF
PH
ENA
GND
BOOT
Z1
Z2
SHDN
SHDN
SHDN
SHDN
SHDN
SHDN
SHDN
SHDN
VIN
112.5%VREF
VSENSE
OVP
HICCUP
HICCUP
SHDN
NC
FeedForward
BOOT
NC
POWERPAD
VIN
VOUT
5 µA
1.221VBandgap
SlowStart
Boot
Regulator
Error
Amplifier
Gain=25
PWM
Comparator
Protection
Gate
Driver
Control
VSENSE
DETAILED DESCRIPTION
Oscillator Frequency
Voltage Reference
Enable (ENA) and Internal Slow Start
TPS5450-EP
www.ti.com ....................................................................................................................................................................................................... SLVS935 – JULY 2009
The internal free-running oscillator sets the PWM switching frequency at 500 kHz. The 500-kHz switching
frequency allows less output inductance for the same output ripple requirement resulting in a smaller output
inductor.
The voltage reference system produces a precision reference signal by scaling the output of a temperature
stable bandgap circuit. The bandgap and scaling circuits are trimmed during production testing to an output of
1.221 V at room temperature.
The ENA pin provides electrical on/off control of the regulator. Once the ENA pin voltage exceeds the threshold
voltage, the regulator starts operation and the internal slow start begins to ramp. If the ENA pin voltage is pulled
below the threshold voltage, the regulator stops switching and the internal slow start resets. Connecting the pin
to ground or to any voltage less than 0.5 V disables the regulator and activates the shutdown mode. The
quiescent current of the TPS5450 in shutdown mode is 18 µ A (typical).
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Product Folder Link(s): TPS5450-EP