Datasheet
8.0V to 35V, 1.5A 1ch
Buck Converter with Integrated FET
BD9870FPS
General Description
The BD9870FPS is a single-channel step-down
switching regulator integrated with a P-Channel
MOSFET capable of PWM operation at 900 kHz. It
employs the use of smaller coil and circuitry to eliminate
the need for external compensation. The circuitry
consists only of a diode, coil and ceramic capacitor thus
reducing the board size significantly.
Key Specifications
Input Voltage Range:
8.0V to 35.0V
Output Voltage Range:1.0V to0.8Vx(V
CC
-I
OUT
xR
ON
)V
Output Current:
1.5A(Max)
Switching Frequency:
900kHz(Typ)
Output ON-Resistance:
1.0Ω(Typ)
Standby Current:
0μA (Typ)
Operating Temperature Range:
-40°C to +85°C
Features
Built-in P-Channel MOSFET for High Efficiency
Adjustable Output Voltage Via External Resistors
Soft-Start Time: 5ms (Fixed)
Built-In Over-Current Protection and Thermal
Shutdown Circuits
ON/OFF Control Via STBY Pin
Ceramic Output Capacitor Compatibility
Package
W(Typ) x D(Typ) x H(Max)
Applications
TVs, Printers, DVD Players, Projectors, Gaming
Devices, PCs, Car Audio/Navigation Systems, ETCs,
Communication Equipment, AV Products, Office
Equipment, Industrial Devices, and more.
TO252S-5
6.50mm x 9.50mm x 1.30mm
Typical Application Circuit
V
IN
VCC
＋
L
1
OUT
＋
Vo
C
IN0
C
IN1
Figur
e 6.
Oscill
ator
Freq
uenc
y vs.
Suppl
y
Volta
ge
D
1
C
O
R
1
STBY
INV
R
2
GND
Figure 1. Typical Application Circuit
○Product
structure：Silicon monolithic integrated circuit
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.
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product has no designed protection against radioactive rays
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BD9870FPS
Pin Configuration
TO252S-5
(TOP VIEW)
GND
OUT
Figure 2. Pin Configuration
VCC
OUT
INV
STBY
Pin Description
Pin No.
1
2
3
(Note 1)
FIN
4
5
(Note 1) Normally OPEN
Pin Name
VCC
OUT
OUT
GND
INV
STBY
Function
Input power supply pin
Internal Pch FET drain pin
Internal Pch FET drain pin
Ground
Output voltage feedback pin
ON/OFF control pin
Block Diagram
VCC
1
VREF
PW
COMP
M
DRIVER
OSC
STBY 5
STBY
CTL
LOGIC
TSD
OCP
2 OUT
Error AMP
4 INV
SS
GND(FIN)
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BD9870FPS
Absolute Maximum Ratings
(Ta=25°C)
Parameter
Supply Voltage（VCC-GND）
STBY-GND
OUT-GND
INV-GND
Maximum Switching Current
Power Dissipation
Operating Temperature
Storage Temperature
Symbol
V
CC
V
STBY
V
OUT
V
INV
I
OUT
Pd
Topr
Tstg
Rating
36
36
36
5
1.5
(Note 1)
0.8
(Note 2)
-40 to +85
-55 to +150
Unit
V
V
V
V
A
W
°C
°C
(Note 1) Do not exceed Pd, ASO, and Tjmax=150°C
(Note 2) Derate by 6.4mW/°C when operating above Ta=25°C
Caution:
Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit
between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is operated over
the absolute maximum ratings.
Recommended Operating Conditions
(Ta=-40°C to +85°C)
Parameter
Input Voltage
Output Voltage
Symbol
V
CC
V
OUT
Limit
Min
8.0
1.0
Max
35.0
0.8 x
(V
CC
-I
OUT
x
R
ON
)
Unit
V
V
Electrical Characteristics
(Unless otherwise specified, Ta=25°C,V
CC
=12V,V
OUT
=5V,V
STBY
=3V)
Limit
Parameter
Symbol
Min
Typ
Output ON-Resistance
Efficiency
Switching Frequency
Load Regulation
Line Regulation
Over-Current Protection Limit
INV Pin Threshold Voltage
INV Pin Input Current
STBY Pin Threshold
Voltage
STBY Pin Input Current
Circuit Current
Stand-by Current
Soft-Start Time
ON
OFF
R
ON
η
f
OSC
ΔV
OUTLOAD
ΔV
OUTLINE
I
OCP
V
INV
I
INV
V
STBYON
V
STBYOFF
I
STBY
I
CC
I
ST
t
SS
-
80
810
-
-
1.6
0.99
-
2.0
-0.3
5
-
-
1
1.0
88
900
5
5
-
1.00
1
-
-
15
5
0
4
Unit
Ω
%
kHz
mV
mV
A
V
μA
V
V
μA
mA
μA
ms
V
STBY
=3V
V
INV
=2V
V
STBY
＝0V
V
INV
=1.0V
V
CC
=20V,
I
OUT
=0.5A to 1.5A
V
CC
=10V to 30V,
I
OUT
=1.0A
I
OUT
＝0.5A
Conditions
Max
1.5
-
990
40
25
-
1.01
2
36
+0.3
30
12
5
10
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BD9870FPS
Typical Performance Curves
(Unless otherwise specified, Ta=25°C,V
CC
=12V,V
OUT
=5V, V
STBY
=3V)
I
OUT
=0mA
V
STBY
=0
V
Circuit Current [mA]
Stand-by Current [µA]
V
CC
=8V
V
CC
=12V
V
CC
=24V
V
CC
=35V
Input Voltage [V]
Figure 3. Circuit Current vs Supply Voltage
(No Load)
Ambient Temperature [°C]
Figure 4. Stand-by Current vs Ambient Temperature
Oscillator Frequency [kHz]
Input Voltage [V]
Figure 5. Oscillator Frequency vs Supply Voltage
Oscillator Frequency [kHz]
Ambient Temperature [°C]
Figure 6. Oscillator Frequency vs Ambient Temperature
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BD9870FPS
Typical Performance Curves - continued
Threshold Voltage [V]
Input Voltage [V]
Figure 7. Error Amp Threshold Voltage vs Supply Voltage
Output Voltage [V]
STBY Input Voltage [V]
Figure 8. Output Voltage vs STBY Input Voltage
V
CC
=8V
V
CC
=8V
Drain-Source Voltage [V]
V
CC
=12V
Efficiency [%]
V
CC
=12V
V
CC
=24V
V
CC
=35V
Output Current [A]
Figure 9. Driver Drain-Source Voltage vs Output Current
Load Current [A]
Figure 10. Efficiency vs Load Current
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