BAXXBC0_10 Datasheet, PDF (5/10 Pages) Rohm – 1A Secondary LDO Regulators for Local Power Supplies

BA□□BC0 Series,BA□□BC0W Series,BA00BC0W Series
Technical Note
Input / Output Equivalent Circuit Diagrams
Vcc
Vcc
CTL
27kΩ 2kΩ
31kΩ
Fig.16
R2
R1
Fig.17
* For the BA00BC0WT, connect R1 and
R2 externally between the C and GND
pins and between the OUT and C pins.
OUT
Equation: VOUT = Vc  (R1 + R2) / R1
(Vc = 1.25 V (Typ.))
The recommended R1 value is
approximately 30 k to 150 k.
Thermal Derating Curves
 TO220FP-3/TO220FP-5/TO220FP-5V5）
25
(1) When using an infinite heat sink.
(1)20.0
20
j-c = 6.25 (°C/W)
(2) During IC without heat sink operation.
j-a = 62.5 (°C/W)
15
10
 TO252-3/TO252-5
2.0
IC mounted on a ROHM standard board
1.6
1.30
Board size: 70  70  1.6 mm
Copper foil area: 7  7 mm
TO252-5 ja=96.2 (°C/W)
TO252-3 ja＝104.2 (°C/W)
1.2
TO252-5
0.8
5
(2)2.0
0
0
25 50 75 100 125 150
AMBIENT TEMPERATURE：Ta [°C]
Fig.18
TO252-3
0.4
0
0
25 50 75 100 125 150
AMBIENT TEMPERATURE：Ta [°C]
Fig.19
The characteristics of the IC are greatly influenced by the operating temperature. If the temperature exceeds the maximum
junction temperature Tjmax, deterioration or damage may occur. Implement proper thermal designs to ensure that power
dissipation is within the permissible range in order to prevent instantaneous damage resulting from heat and maintain the
reliability of the IC for long-term operation.
The following method is used to calculate the power consumption Pc (W).
Pc = (Vcc – Vo)  Io + Vcc  Icca
Power dissipation Pd ≥ Pc
The load current Io is calculated:
Vcc : Input voltage
Vo : Output current
IO : Load current
Icca : Circuit current
Io ≤ ^{Pd − Vcc  Icca}
Vcc − Vo
Calculation Example:
Vcc = 6.0 V and Vo = 5.0 V at Ta = 85°C
0.676 − 6.0  Icca
6.0 − 5.0
ja = 96.2°C/W → −10.4 mW/°C
25°C = 1300 mW → 85°C = 676 mW
Io ≤ 550 mA (Icca  20 mA)
Refer to the above and implement proper thermal designs so that the IC will not be used under excessive power dissipation
conditions under the entire operating temperature range.
The power consumption Pc of the IC in the event of shorting (i.e. the Vo and GND pins are shorted) can be obtained from the
following equation:
Pc = Vcc  (Icca + Ishort) (Ishort: short current).
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2010.02 - Rev.B