S-8521F25MC-BPKT2G Seiko Instruments, S-8521F25MC-BPKT2G Datasheet - Page 24

• Manufacturer Part Number: S-8521F25MC-BPKT2G
• Description: IC REG PWM/PFM 300KHZ SOT23-5
• Manufacturer: Seiko Instruments
• Type: Step-Down (Buck)r

Specifications of S-8521F25MC-BPKT2G

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 2.5V
• 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: 2.5 V
• Input Voltage: 2.5 V to 16 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

24
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
S-8520/8521 Series
The voltage accuracy of the OUT cannot be made higher than the output voltage accuracy (V
itself, without adjusting the R
voltage value (V
in the absolute accuracy of R
influence of deviations in R
limited to a much smaller value than that of R
On the other hand, a reactive current flows through R
negligible value with respect to the load current in the actual use of the IC so that the efficiency characteristics will
not be degraded. This requires that the value of R
However, too large a value (more than 1 MΩ) for the R
Check the influence of this value on actual equipment.
There is a tradeoff between the voltage accuracy of the OUT and the reactive current. This should be taken into
consideration based on the requirements of the intended application.
Deviations in the absolute value of the internal resistances (R
S-8520/8521 Series, and are broadly classified as follows:
When a value of R
output OUT, a median voltage deviation will be obtained for the OUT.
Moreover, add a capacitor (C
other types of instability (Refer to Figure 14).
Make sure that C
If a large C
Caution
R
of R
C
1
C
+ R
[F] ≥ 1 ÷ (2 × π × R
1
and R
2
C
The above connection diagram and constant will not guarantee successful operation. Perform
through evaluation using the actual application to set the constant.
= 2 ÷ (1 ÷ maximum deviation in absolute value of R
value is selected, a longer soft start time than the one set up in the IC will be set.
2
)
OUT
Output voltage
C
1.5 V to 2.0 V
2.1 V to 2.5 V
2.6 V to 3.3 V
3.4 V to 4.9 V
5.0 V to 6.0 V
is larger than the value given by the following equation:
) of the IC are brought to one other, the more the output voltage remains immune to deviations
1
+ R
2
A
1
given by the equation indicated below is taken in calculating the voltage value of the
[Ω] × 7.5 kHz)
and R
A
A
C
) in parallel to the external resistance (R
and R
and R
2
in the IC, a major contributor to deviations in the OUT, the R
B
B
and the absolute value of R
Deviations in the absolute value of R
involved. The closer the voltage value of the output OUT and the output
Seiko Instruments Inc.
1
and R
A
Table 10
and R
2
in the IC.
5.16 MΩ to 28.9 MΩ
4.44 MΩ to 27.0 MΩ
3.60 MΩ to 23.3 MΩ
2.44 MΩ to 19.5 MΩ
2.45 MΩ to 15.6 MΩ
A
B
A
and R
be made sufficiently large.
and R
1
and R
1
B
and R
would make the IC vulnerable to external noise.
B
1
. This reactive current must be reduced to a
and R
2
) in the IC vary with the output voltage of the
2
A
+ 1 ÷ minimum deviation in absolute value
) in order to avoid output oscillations and
2
1
in the IC. In particular, to suppress the
and R
2
in the IC
OUT
A
±2.4%) of the IC
and R
Rev.9.0
B
must be
_00