R1517 Datasheet, PDF (13/38 Pages) RICOH electronics devices division – Input Voltage Range (Maximum Rating) 3.5 V to 36.0 V (50.0V)

OPERATION DESCRIPTION
R1517x
NO. EA−304−170112
Thermal Shutdown Function
Thermal shutdown function is included in this device. If the junction temperature is more than or equal to 160°C
(Typ.), the operation of the regulator would stop. After that, when the junction temperature is less than or equal to
135°C (Typ.), the operation of the regulator would restart. Unless the cause of rising temperature is removed, the
regulator repeats on and off, and output waveform would be like consecutive pulses.
Adjustable Output Voltage Setting (R1517x001C)
The output voltage of R1517x001C can be adjusted by using the external divider resistors (R1, R2). By using the
following equation, the output voltage (VOUT) can be determined. The voltage which is fixed inside the IC is
described as VFB.
VOUT = VFB x ((R1 + R2) / R2)
Recommended Range: 2.5 V ≤ VOUT ≤ 12.0 V
VFB = 2.5 V
VOUT
VFB
RIC
GND
R1 ^I1
IIC
VOUT
R2
I2
VFB
Output Voltage Adjustment Using External Divider Resistors (R1, R2)
RIC of the R1517x001C is approximately Typ. 1.35 MΩ (Ta=25C, guaranteed by design engineering). For better
accuracy, setting R1 << RIC reduces errors. The resistance value for R2 should be set to 10 kΩ or lower. It is
easily affected by noises when setting the value of R1 and R2 larger, which makes the impedance of VFB pin
larger.
RIC could be affected by the temperature, therefore evaluate the circuit taking the actual conditions of use into
account when deciding the resistance values for R1 and R2.
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