TECHNICAL NOTE
High-performance Regulator IC Series for PCs
Ultra Low Dropout
Linear Regulators for PC Chipsets
BD3508EKN
●
Description
The BD3508EKN ultra low-dropout linear chipset regulator operates from a very low input supply, and offers ideal
performance in low input voltage to low output voltage applications. It incorporates a built-in N-MOSFET power transistor to
minimize the input-to-output voltage differential to the ON resistance (R
ON
=65mΩ) level. By lowering the dropout voltage in
this way, the regulator realizes high current output (Iomax=3.0A) with reduced conversion loss, and thereby obviates the
switching regulator and its power transistor, choke coil, and rectifier diode. Thus, the BD3508EKN is designed to enable
significant package profile downsizing and cost reduction. An external resistor allows the entire range of output voltage
configurations between 0.65 and 2.7V, while the NRCS (soft start) function enables a controlled output voltage ramp-up,
which can be programmed to whatever power supply sequence is required.
●
Features
1) Internal high-precision reference voltage circuit(0.65V±1%)
2) Built-in VCC under voltage lock out circuit (VCC=3.80V)
3) NRCS (soft start) function reduces the magnitude of in-rush current
4) Internal Nch MOSFET driver offers low ON resistance (65mΩ typ)
5) Built-in current limit circuit(3.0A min)
6) Built-in thermal shutdown (TSD) circuit
7) Variable output (0.65½2.7V)
8) Incorporates high-power HQFN20V package: 4.2×4.2×0.9(mm)
●
Applications
Notebook computers, Desktop computers, LCD-TV, DVD, Digital appliances
●
Model Lineup
Oct. 2008
●
Absolute Maximum Ratings
◎BD3508EKN
○Absolute
Maximum Ratings(Ta=100℃)
PARAMETER
Input Voltage 1
Input Voltage 2
Enable Input Voltage
Power Dissipation 1
Power Dissipation 2
Power Dissipation 3
Power Dissipation 4
Operating Temperature Range
Storage Temperature Range
Maximum Junction Temperature
SYMBOL
VCC
VIN
Ven
Pd1
Pd2
Pd3
Pd4
Topr
Tstg
Tjmax
RATING
6.0 *
1
6.0 *
1
6.0
0.5
*2
0.75
*3
1.75
*4
2.0
*5
-10½+100
-55½+125
+150
UNIT
V
V
V
W
W
W
W
℃
℃
℃
*
1
Should not exceed Pd.
*
2
Reduced by 4mW/℃ for each increase in Ta≧25℃(no heat sink)
*
3
Reduced by 6mW/℃ for each increase in Ta≧25℃ (when mounted on a 70mm×70mm×1.6mm glass-epoxy board,
with no copper foil on the bottom surface)
*
4
Reduced by 14mW/℃ for each increase in Ta≧25℃ (when mounted on a 70mm×70mm×1.6mm glass-epoxy board,
with 60mm X 60 mm copper foil on the bottom surface…1-layer)
*
5
Reduced by 16mW/℃ for each increase in Ta≧25℃ (when mounted on a 70mm×70mm×1.6mm glass-epoxy board,
with 60mm X 60 mm copper foil on the bottom surface…2-layer)
●Operating
Conditions
○Operating
Voltage(Ta=25℃)
PARAMETER
Input Voltage 1
Input Voltage 2
Output Voltage Setting Range
Enable Input Voltage
NRCS Capacity
SYMBOL
VCC
VIN
Vo
Ven
CNRCS
MIN.
4.3
0.75
VFB
-0.3
0.001
MAX.
5.5
VCC-1 *
6
2.7
5.5
1
UNIT
V
V
V
V
uF
*
6
VCC and VIN do not have to be implemented in the order listed.
★This
product is not designed for use in radioactive environments.
●Electrical
Characteristics (Unless otherwise specified, Ta=25℃ VCC=5V Ven=3V VIN=1.8V R1=3.9KΩ R2=3.3KΩ)
Limit
Typ.
0.7
0
1.200
-
-
0.01
0.650
0.650
0.1
0.1
0.5
65
-
Parameter
Bias Current
VCC Shutdown Mode Current
Output Voltage
Maximum Output Current
Output Short Circuit Current
Output Voltage Temperature
Coefficient
Feedback Voltage 1
Feedback Voltage 2
Line Regulation 1
Line Regulation 2
Load Regulation
Minimum Input-Output Voltage
Differential
Standby Discharge Current
[ENABLE]
Enable Pin
Input Voltage High
Enable Pin
Input Voltage Low
Enable Input Bias Current
[FEEDBACK]
Feedback Pin Bias Current
[NRCS]
NRCS Charge Current
NRCS Standby Voltage
[UVLO]
VCC Under voltage Lock out
Threshold Voltage
VCC Under voltage Lock out
Hysteresis Voltage
[AMP]
Gate Source Current
Gate Sink Current
*7 Design targets
Symbol
ICC
IST
VOUT
Io
Iost
Tcvo
VFB1
VFB2
Reg.l1
Reg.l2
Reg.L
dVo
Iden
Min.
-
-
-
3.0
3.0
-
0.643
0.630
-
-
-
-
1
Max.
1.4
10
-
-
-
-
0.657
0.670
0.5
0.5
10
100
-
Unit
mA
uA
V
A
A
%/℃
V
V
%/V
%/V
mV
mV
mA
Condition
Ven=0V
Vo=0V
Io=0 to 3A
7
Ta=-10 to 100℃ *
VCC=4.3V to 5.5V
VIN=1.2V to 3.3V
Io=0 to 3A
Io=1A,VIN=1.2V
7
Ta=-10 to 100℃ *
Ven=0V, Vo=1V
Enhi
Enlow
Ien
IFB
Inrcs
VSTB
2
-0.2
-
-100
14
-
-
-
7
0
20
0
-
0.8
10
100
26
50
V
V
uA
nA
uA
mV
Vnrcs=0.5V
Ven=0V
Ven=3V
VccUVLO
Vcchys
3.5
100
3.8
160
4.1
220
V
mV
VCC:Sweep-up
VCC:Sweep-down
I
GSO
I
GSI
-
-
1.6
4.7
-
-
mA
mA
V
FB
=0, V
GATE
=2.5V
V
FB
=VCC, V
GATE
=2.5V
●
Reference Data
Vo
50mV/div
45mV
Vo
50mV/div
64mV
Vo
100mV/div
91mV
Io
2A/div
3.0A
Io
2A/div
3.0A
Io
2A/div
3.0A
Io=0A→3A/3μsec
t(5μsec/div)
Io=0A→3A/3μsec
t(5μsec/div)
Io=0A→3A/3μsec
t(5μsec/div)
Fig.1 Transient response (0→3A)
Co=150μF×2
Fig.2 Transient response (0→3A)
Co=150μF
Fig.3 Transient response (0→3A)
Co=47μF
Vo
50mV/div
55mV
Vo
50mV/div
79mV
Vo
100mV/div
87mV
Io
2A/div
3.0A
Io
2A/div
3.0A
Io
2A/div
3.0A
Io=3A→0A/3μsec
t(5μsec/div)
Io=3A→0A/3μsec
t(5μsec/div)
Io=3A→0A/3μsec
t(5μsec/div)
Fig.4 Transient response (3→0A)
Co=150μF×2
Fig.5 Transient response (3→0A)
Co=150μF
Fig.6 Transient response (3→0A)
Co=47μF
Ven
2V/div
Ven
2V/div
VCC
Ven
VNRCS
2V/div
Vo
1V/div
t(200μsec/div)
VNRCS
2V/div
VIN
Vo
1V/div
t(2msec/div)
Vo
VCC→VIN→Ven
Fig.7 Waveform at output start
Fig.8 Waveform at output OFF
Fig.9 Input sequence
VCC
VCC
VCC
Ven
Ven
Ven
VIN
VIN
VIN
Vo
VIN→VCC→Ven
Vo
Ven→VCC→VIN
Vo
VCC→Ven→VIN
Fig.10 Input sequence
Fig.11 Input sequence
Fig.12 Input sequence
1.25
VCC
VCC
1.23
Vo(V)
Ven
Ven
1.21
1.19
VIN
VIN
1.17
Vo
VIN→Ven→VCC
Vo
1.15
Ven→VIN→VCC
-10
10
30
50
Ta(℃)
70
90
100
Fig.13 Input sequence
1.00
0.95
0.90
0.85
ICC(mA)
ICC(uA)
0.80
0.75
0.70
0.65
0.60
0.55
0.50
-10
10
30
50
Ta(℃)
70
90
100
Fig.14 Input sequence
1.2
1
0.8
0.6
0.4
0.2
0
-60
-30
0
30
60
Ta(℃)
90
120 150
IIN(mA)
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
-10
Fig.15 Ta-Vo (Io=0mA)
10
30
50
Ta(℃)
70
90
100
Fig.16 Ta-ICC
25
Fig.17 Ta-ISTB
20
15
10
IFB(nA)
5
0
-5
-10
-15
-20
-10
10
30
50
Ta(℃)
70
90
Fig.18 Ta-IIN
30
25
INRCS(uA)
24
23
22
20
IIN(uA)
15
10
5
0
-60
-30
0
30
60
Ta(℃)
90
120
150
21
20
19
18
17
16
15
100
-10
10
30
50
Ta(℃)
70
90 100
Fig.19 Ta-IINSTB
10
9
8
7
Fig.20 Ta-INRCS
60
50
40
RON(m
Ω
)
RON(m
Ω
)
30
20
35
10
0
-10
30
25
10
30
50
Ta(
℃
)
70
90
100
2
60
55
50
Fig.21 Ta-IFB
2.5V
1.8V
Ien(uA)
6
5
4
3
2
1
0
-10
10
30
50
Ta(℃)
70
90 100
45
40
1.2V
4
Vcc(V)
6
8
Fig.22 Ta-Ien
Fig.23 Ta-RON
(VCC=5V/Vo=1.2V)
Fig.24 VCC-RON
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