Datasheet
0.65V to 5.5V, 1ch
Ultra Low Dropout Linear Regulator Controller
BD3504FVM
General Description
BD3504FVM is an ultra-low dropout linear regulator
controller for chipset that can achieve ultra-low input to
output voltage. By using N-MOSFET for external power
transistor, the controller can be used at ultra-low I/O
voltage difference as low as the voltage generated by
ON-Resistance. By reducing the I/O voltage difference,
large output current is achieved and conversion loss can
be reduced, thus the controller can be used in
replacement of a switching power supply. In addition,
downsizing and cost reduction of the set can be
achieved as suitable power transistor can be selected
depending on the output current. BD3504FVM does not
need any choke coil, diode for rectification and power
transistor which are all necessary in a switching power
supply, thus reduced total cost and compact size can be
achieved for the set. Using external resistors, output
voltage ranging from 0.65V to 2.5V can be selected. It
is also possible to meet the power supply sequence of
the set since output voltage start-up time can be
adjusted by using the NRCS terminal.
Key Specifications
Drain Voltage Range:
0.65V to 5.5V
Supply Voltage Range:
4.5V to 5.5V
Output Voltage Range:
0.65V to 2.5V
External FET GATE Drive Current:
±3mA(Typ)
Standby Current:
0µA (Typ)
Operating Temperature Range:
-10°C to +100°C
Package
W(Typ) x D(Typ) x H(Max
)
Features
Reduced rush current by NRCS
Built-in driver for external Nch transistor
Built-in timer latch short protection circuit
Built-in under voltage lock out circuit
Output voltage variable type
Built-in thermal shutdown circuit
MSOP8
2.90mm x 4.00mm x 0.90mm
Applications
Mobile PC, desktop PC, digital home appliances
Typical Application Circuit and Block Diagram
VCC
VCC
4
VD
UVLO2
R2’
R
2
’
IN
VIN
Enable
EN
3
UVLO1
Reference
Block
NRCS
0.65V
0.65V
VD
UVLO
LATCH
8
UVLO1
EN
VREF
R
1
’
R1’
G
7
TSD
SCP
UVLO1
UVLO2
EN
VS
6
R2
R
2
VFB
5
SCP
R1
R
1
OUT
Vo
Thermal
Protection
TSD
0.65V
SCP
NRCS
NRCS
1
NRCS
2
GND
○Product
structure：Silicon monolithic integrated circuit
.
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BD3504FVM
Pin Configuration
TOP VIEW
1
NRCS
GND
EN
VCC
VFB
VS
G
VD
Pin Descriptions
Pin
No.
Pin
Name
Pin Function
NRCS (Non Rush Current on Start up) time
setup. Timer latch setup for Short Circuit
Protection operating time set up Pin.
Ground pin
Enable pin
Power source
Output voltage feedback
Source voltage pin
MOSFET driver output
Drain voltage sense
NRCS
1
8
VD
2
3
GND
EN
VCC
2
7
6
G
4
5
3
VS
6
7
4
5
VFB
8
Description of Operations
1. VCC
BD3504FVM has an independent power input pin for the internal circuit operation of the IC. This is used to bias the IC
internal circuit and external N-Channel MOSFET. The voltage used for VCC terminal is 5.0V and maximum current is
1.7mA.
It is recommended to connect a bypass capacitor with a value of 1µF or more to VCC pin.
2. EN
With an input of 2.0V or higher, the EN terminal turns to “High” level and OUT is produced. At 0.8V or lower, it detects
“Low” level and OUT is turned OFF. Simultaneously, the discharge circuit inside the VS terminal is activated and output
voltage is reduced (150 mA (Min) when V
VS
=1V and V
EN
=0V).
3. VD
The VD terminal is the drain voltage detection terminal of the external N-Channel MOSFET. When drain voltage (IN) is low,
output voltage is turned OFF to prevent under voltage lock out. The reset voltage (V
DUVLO
) of under voltage lock out circuit
is determined by the following equation:
R
'
R
2
'
V
VDUVLO
½
V
IN
0.7
1
R
'
1
At low-input drain voltage, when UVLO resistors have resistance values same as output voltage resistors (R
1
= R
1
’, R
2
=
R
2
’), under voltage lock out (UVLO) is reset when drain voltage (IN) reaches 70% of the output voltage. UVLO detects
only at the startup of the EN terminal.
4. VFB
The VFB terminal is use to decide the output voltage and is determined by the following equation:
R
R
2
V
OUT
½
V
VFB
1
R
1
where:
V
VFB
is controlled to achieve 0.65 V (typ).
5. NRCS terminal
The NRCS terminal is a constant current output terminal, and operates as
Soft-Start ... during start-up
SCP-Delay ... after start-up
How to set Soft-Start of NRCS terminal
The output voltage startup time (t
NRCS
) is determined by the time when the NRCS terminal reaches V
VFB
(0.65V).
During start-up, the NRCS terminal serves as a constant current source (I
NRCS
) of 20 µA (Typ) output, and charges
externally connected capacitor (C
NRCS
). Output voltage (V
OUT
) becomes stable when NRCS terminal reaches the
internal reference voltage (0.65V).
How to set NRCS terminal short protection Delay
BD3504FVM has short circuit protection (SCP) which is activated when output voltage becomes V
OUT
x 0.35 (typ) or
lower. The time when SCP is activated until latch takes place (t
SCP
) is determined by the following equation:
t
SCP
½
C
NRCS
V
OSCP
I
SCP
When SCP is activated, the NRCS terminal provides 20 µA (typ) constant current output (l
SCP
), and charges the externally
connected capacitor (C
NRCS
). When the NRCS terminal reaches 1.3V (V
OSCP
), latch operation is carried out and output
voltage is turned OFF.
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BD3504FVM
Description of Operations – continued
6. VS
VS terminal is a source voltage detection terminal of the external N-Channel MOSFET. VFB//VS terminal has the internal
discharge circuit activated to lower output voltage when EN changes to Low level or various protection circuits (TSD, SCP,
UVLO) are activated.
7. G
G terminal is the gate drive terminal of the external N-Channel MOSFET. Because the output voltage range of G terminal
is up to 5V (VCC), it is necessary to use N-Channel MOSFET whose threshold is lower than “5V - V
OUT
”. In addition, by
including an RC snubber circuit to the G terminal, phase margin of loop gain can be increased and ceramic capacitors can
be used for the terminal.
Absolute Maximum Ratings
(Ta=25°C)
Parameter
Supply Voltage
Drain Voltage
Enable Input Voltage
Power Dissipation
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature
Symbol
V
CC
V
VD
V
EN
Pd
Topr
Tstg
Tjmax
Rating
7
(Note 1)
7
7
0.43
(Note 2)
-10 to +100
-55 to +150
+150
Unit
V
V
V
W
°C
°C
°C
(Note 1) However, not exceeding Pd.
(Note 2) To use at temperature above Ta=25°C, derate by 3.5mW/°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
Parameter
Supply Voltage
Drain Voltage
Enable Input Voltage
Capacitor in NRCS Pin
Output Voltage
Symbol
V
CC
V
VD
V
EN
C
NRCS
V
OUT
Rating
Min
4.5
0.65
-0.3
0.001
0.65
Max
5.5
5.5
+5.5
1
2.5
Unit
V
V
V
µF
V
Electrical Characteristics
(Unless otherwise specified, Ta=25°C V
CC
=5V V
IN
=3.3V V
EN
=3V R
1
=R
1
'=∞Ω, R
2
=R
2
'=0Ω)
Standard Value
Parameter
Symbol
Unit
Min
Typ
Max
Circuit Current
Shut Down Mode Current
Feed Back Voltage 1
Feed Back Voltage 2
Output Voltage
Line Regulation
Load Regulation
[Enable]
High Level Enable Input Voltage
Low Level Enable Input Voltage
Enable Pin Input Current
(Note) Not 100% tested
Conditions
I
CC
I
ST
V
VFB1
V
VFB2
V
OUT
Reg.l
Reg.L
V
ENHI
V
ENLOW
I
EN
-
-
0.643
0.630
-
-
-
2
-0.3
-
0.85
0
0.650
0.650
1.20
0.1
0.5
-
-
7
1.7
10
0.657
0.670
-
0.5
10
V
CC
+0.8
10
mA
µA
V
V
V
%/V
mV
V
V
µA
V
EN
=3V
V
EN
=0V
I
OUT
=50mA
V
CC
=4.5V to 5.5V ,
Ta=-10°C to +100°C
(Note)
R
1
=R
1
'=3.9kΩ,
R
2
=R
2
'=3.3KΩ
V
CC
=4.5V to 5.5V
I
OUT
=0A to 3A
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BD3504FVM
Electrical Characteristics- continued
(Unless otherwise specified, Ta=25°C V
CC
=5V V
IN
=3.3V V
EN
=3V R
1
=R
1
'=∞Ω, R
2
=R
2
'=0Ω)
Standard Value
Parameter
Symbol
Unit
Min
Typ
Max
[Voltage Feed Back]
VFB Input Bias Current
[Source Voltage]
VS Input Bias Current
VS Standby Current
[Output MOSFET Driver]
MOSFET Driver Source Current
MOSFET Driver Sink Current
[UVLO]
VCC UVLO
VCC UVLO Hysterisis
VD UVLO
[Drain Voltage Sensing]
VD Input Bias Current
[NRCS/SCP]
NRCS Charge Current
SCP Charge Current
SCP Discharge Current
SCP Threshold Voltage
Short Detect Voltage
NRCS Stand-by Voltage
I
NRCS
I
SCPCH
I
SCPDI
V
SCP
V
OSCP
V
STB
14
14
0.3
1.2
-
20
20
-
1.3
-
26
26
-
1.4
50
µA
µA
mA
V
V
mV
V
NRCS
=0.5V
V
NRCS
=0.5V
V
NRCS
=0.5V
I
VD
-
0
-
nA
V
CCUVLO
V
CCHYS
V
VDUVLO
4.20
100
4.35
160
4.50
220
V
mV
V
VCC: Sweep up
VCC: Sweep down
VD: Sweep up
I
GSO
I
GSI
2
2
3
3
4
4
mA
mA
V
VFB
=0.6V, V
GATE
=2.5V
V
VFB
=0.7V, V
GATE
=2.5V
I
SBIAS
I
SSTB
-
150
1.2
-
2.4
-
mA
mA
V
VS
=1V V
EN
=0V
I
VFB
-
80
-
nA
Conditions
V
OUT
x0.6 V
OUT
x0.7 V
OUT
x0.8
V
OUT
x0.3 V
OUT
x0.35 V
OUT
x0.4
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BD3504FVM
Typical Performance Curves
1.40
0.80
1.20
Standby Current : I
STB
(µA)
Circuit Current : I
CC
(mA)
0.60
1.00
0.80
0.40
0.60
0.40
0.20
0.20
0.00
-60
-10
40
Ta(℃)
Temperature : Ta
90
140
0.00
4.5
4.7
4.9
(°C)
Supply
5.1
VCC(V)
:
Voltage
5.3
5.5
V
CC
(V)
Figure 1. Standby Current vs Temperature
Figure 2. Circuit Current vs Supply Voltage
1.800
12
1.795
Enable Pin Input Current : I
EN
(µA)
11
Output Voltage : V
OUT
(V)
1.790
10
1.785
9
1.780
8
1.775
7
1.770
-10
15
40
65
90
6
25
50
75
100
125
150
Temperature : Ta (°C)
Figure 3. Output Voltage vs Temperature
Temperature : Ta (°C)
Figure 4. Enable Pin Input Current vs Temperature
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