S-8521F25MC-BPKT2G Seiko Instruments, S-8521F25MC-BPKT2G Datasheet - Page 23

• 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

Rev.9.0
1. External adjustment of output voltage
Application Circuits
In the S-8550/8521 Series, by adding external resistors (R
adjusted or be set freely in the range of 1.5 to 6.0 V, as shown in Figure 14. Temperature gradient can be given by
inserting a thermistor in series to R
Caution
The S-8520/8521 Series have an internal impedance of R
shown in Figure 14.
Therefore, OUT (the output voltage) is determined by the output voltage value (V
and the ratio of the parallel resistance value of external resistance (R
to external resistance (R
The voltage accuracy of the OUT set by resistances (R
accuracy (V
absolute value deviations of internal resistances (R
Let us designate the maximum deviations of the absolute value of R
the minimum deviations by R
absolute value of R
deviation value OUT min. and the maximum deviation value OUT max. of the OUT are expressed by the following
equations:
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
OUT = V
*1. // shows the combined resistance in parallel.
OUT min. = V
OUT max. = V
_00
+
−
The above connection diagram and constant will not guarantee successful operation. Perform
through evaluation using the actual application to set the constant.
OUT
OUT
ON/OFF
+ V
±2.4 %), but also by the absolute precision of external resistances (R
OUT
______
OUT
VIN
OUT
1
× 0.976 + V
× 1.024 + V
and R
× R
Oscillation
PFM switching control unit
A
). The output voltage is expressed by the following equation:
PWM control or PWM /
Circuit
EXT
A
÷ (R
2
A
in the IC by (R
min. and R
OUT
B
OUT
//
A
*1
source with soft start
S-8520/8521 Series
× 0.976 × R
and R
Reference voltage
× 1.024 × R
(R
1
+ R
B
VSS
Seiko Instruments Inc.
B
.
2
))
min., respectively, and the maximum and minimum deviations of the
1
A
+ R
A
−
+
Figure 14
min. ÷ (R
max. ÷ (R
1
2
and R
) max. and (R
R
R
A
1
2
2
B
and R
) in the IC.
A
1
B
max. // (R
, R
VOUT
min. // (R
and R
B
) and a capacitor (C
B
) is not only affected by the IC’s output voltage
1
2
A
B
and R
+ R
between the VOUT pin and the VSS pin, as
1
) and internal resistances (R
1
+ R
+ R
D1
2
) min., respectively. Then, the minimum
2
B
2
) max.)
) min.)
by R
A
OUT
max. and R
FB
) of the S-8520/8521 Series,
), the output voltage can be
S-8520/8521 Series
A
C
and R
C
B
R
R
max., respectively,
B
A
B
) in use and the
1
+ R
2
+
−
) of the IC,
OUT
23