W-5200-5 Datasheet, PDF (7/11 Pages) Copal Electronics – Low Noise Regulated

W-5200ï5
Device Operation
The:ïuseaswitchedcapacitorchargepump to
boost the voltage at IN to a regulated output voltage.
Regulation is achieved by sensing the outputYRODWDJH
throughaninternalresistordivider(:ïand
modulatingthechargepump outputcurrent based onthe
error signal. A 2ïphase nonïoverlapping clock activates the
charge pump switches. The flying capacitor is charged from
the IN voltage on the first phase of the clock. On the second
phase of the clock it is stacked in series with the input voltage
and connected to OUT. The charging and discharging the
flying capacitor continues at a free running frequency of
typically 2 MHz.
In shutdown mode all circuitry is turned off and the
:ï5  draw only leakage current from the V_IN
supply.OUTisdisconnectedfromIN.TheSHDNpinis a
CMOS input with a threshold voltage of approximately
0.8V.The:ïisinshutdownwhenalogicLOWis
applied to the SHDN pin. The SHDN pin is a high
impedanceCMOSinput.SHDNdoesnothavean
internal pullïdown resistor and should not be allowed to
float and. It must always be driven with a valid logic level.
ShortïCircuit and Thermal Protection
The :ï have EXLOWïLQ shortïcircuit current
limitingandovertemperatureprotection.Duringoverload
conditions, output current is limited to approximately 225
mA.Athighertemperatures,or if the input voltage is high
enough to cause excessive chip self heating, the thermal
shutdown circuit shuts down the charge pump as the
junction temperature exceeds approximately 160oC. Once
the junction temperature drops back to approximately
140oC,thechargepumpisenabled.
The:ïwillcycleinandoutofthermal shutdown
indefinitely without latchïu p or damage until a
shortïcircuit on OUT is removed.
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