ST5R33DEMOBOARD STMicroelectronics, ST5R33DEMOBOARD Datasheet - Page 3

• Manufacturer Part Number: ST5R33DEMOBOARD
• Description: DEMO BOARD FOR ST5R33MTR
• Manufacturer: STMicroelectronics
• Type: Power Management: DC/DC SMPSr

Specifications of ST5R33DEMOBOARD

• Contents: Fully Assembled Evaluation Board
• For Use With/related Products: ST5R33MTR
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-5852

ST5R00 SERIES
OPERATION
The ST5Rxx architecture is built around a VFM CONTROL logic core: switching frequency is set through
a built in oscillator: T
time is fixed (Typ. 5ms) while T
time is determined by the error amplifier
ON
OFF
output, a logic signal coming from the comparison made by the Error Amplifier Stage between the signal
coming from the output voltage divider network and the internal Band-Gap voltage reference (V
). T
ref
OFF
reaches a minimum (Typ. 1.7ms) when heavy load conditions are met (Clock frequency 150KHz). An over
current conditions, through the internal power switch, causes a voltage drop V
=R
xI
and the V
LX
DSON
SW
LX
limiter block forces the internal switch to be off, so narrowing T
time and limiting internal power
ON
dissipation. In this case the switching frequency may be higher than the 150KHz set by the internal clock
generator.
VFM control ensures very low quiescent current and high conversion efficiency even with very light loads.
Since the Output Voltage pin is also used as the device Supply Voltage, the versions with higher output
voltage present an higher internal supply voltage that results in lower power switch R
, slightly greater
DSON
output power and higher efficiency. Moreover, bootstrapping allows the input voltage to sag to 0.6V (at
I
=1mA) once the system is started.
OUT
If the input voltage exceeds the output voltage, the output will follow the input, however, the input or output
voltage must not be forced above 5.5V.
Figure 3: Typical Application Circuit
(*) See application info.
Figure 4: Typical Application Efficiency
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