S-8520F34MC-BNTT2G Seiko Instruments, S-8520F34MC-BNTT2G Datasheet - Page 13

• Manufacturer Part Number: S-8520F34MC-BNTT2G
• Description: IC REG CTRLR PWM 300KHZ SOT23-5
• Manufacturer: Seiko Instruments
• Type: Step-Down (Buck)r

Specifications of S-8520F34MC-BNTT2G

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 3.4V
• Current - Output: 120mA
• Frequency - Switching: 300kHz
• Voltage - Input: 2.5 ~ 16 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Power - Output: 250mW
• Output Voltage: 3.4 V
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Rev.9.0
1. Switching control method
Operation
1. 1 PWM control (S-8520 Series)
1. 2 PWM / PFM switching control (S-8521 Series)
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
The S-8520 Series is a DC-DC converter using a pulse width modulation method (PWM) and features a low
current consumption.
In conventional PFM DC-DC converters, pulses are skipped when the output load current is low, causing a
fluctuation in the ripple frequency of the output voltage, resulting in an increase in the ripple voltage.
The switching frequency does not change, although the pulse width changes from 0 to 100% corresponding to
each load current. The ripple voltage generated from switching can thus be removed easily through a filter
because the switching frequency is constant. And the ripple voltage will be skipped to be low current
consumption when the pulse width is 0% or it is no load, input current voltage is high.
S-8521 Series is a DC-DC converter that automatically switches between a pulse width modulation method
(PWM) and a pulse frequency modulation method (PFM), depending on the load current, and features low
current consumption.
The S-8521 Series operates under PWM control with the pulse width duty changing from 25 to 100% in a high
output load current area.
The S-8521 Series operates under PFM control with the pulse width duty fixed at 25%, and pulses are skipped
according to the load current. The oscillation circuit thus oscillates intermittently so that the resultant lower self
current consumption prevents a reduction in the efficiency at a low load current. The switching point from PWM
control to PFM control depends on the external devices (coil, diode, etc.), input voltage and output voltage.
The S-8521 Series is an especially highly efficient DC-DC converter at an output current around 100 μA.
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Seiko Instruments Inc.
S-8520/8521 Series
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