SC431L Datasheet

SC431L
Low Voltage Adjustable
Shunt Regulator
POWER MANAGEMENT
Description
Features
The SC431L is a three terminal adjustable shunt
regulator with thermal stability guaranteed over
temperature. The output voltage can be adjusted to any
value from 1.24V (V REF ) to 20V with two external
resistors. The SC431L has a typical dynamic output
impedance of 0.05Ω. Active output circuitry provides a
very sharp turn on characteristic, making the SC431L an
excellent replacement for zener diodes.
‹
‹
‹
‹
‹
‹
The SC431L shunt regulator is available with four voltage tolerances (0.25%, 0.5%, 1.0% and 2.0%), two
operating temperature ranges (commercial and industrial) and two package options (SOT-23-3 and SOT-235). This allows the designer the opportunity to select the
optimum combination of cost and performance for their
application.
Applications
‹
‹
‹
‹
‹
‹
Low voltage operation (down to 1.24V)
Wide operating current range 100µA to 100mA
Low dynamic output impedance 0.05 Ω typ.
Trimmed bandgap design ± 0.25%
Upgrade for TLV431A
SOT-23-3 and SOT-23-5 packages. Also available in
Lead-free package, fully WEEE and RoHS compliant
Linear Regulators
Adjustable Supplies
Switching Power Supplies
Battery Operated Computers
Instrumentation
Computer Disk Drives
Typical Application Circuit(1)(2)
Notes:
1) Set VOUT according to the following equation:
R1 

VOUT = VREF 1 +
 + IREF R1
R
2

2) Choose the value for R as follows:
• The maximum limit for R should be such that the
cathode current, I Z , is greater than the minimum
operating current (100µA) at VIN(MIN).
• The minimum limit for R should be such that IZ does
not exceed 100mA under all load conditions, and the
instantaneous turn-on value for I Z does not exceed
150mA. Both of the following conditions must be met:
R min ≥
R min ≥
V IN (max)
150 mA
(to limit instantaneous turn-on IZ)
V IN (max) − V OUT
I OUT (min) + 100 mA
(to limit IZ under normal
operating conditions)
Revision: May 16, 2008
1
www.semtech.com
SC431L
POWER MANAGEMENT
Absolute Maximum Ratings
Parameter
Symbol
Maximum
Units
Cathode Voltage
VZ
20
V
Continous Cathode Current
IZ
100
mA
Reference Input Current
IREF
3
mA
Power Dissipation at TA = 25°C
SOT-23-3
SOT-23-5
PD
0.37
0.49
W
Thermal Resistance
SOT-23-3
SOT-23-5
θJ A
336
256
°C/W
Operating Ambient Temperature Range
S C 431LC
S C 431LI
TA
0 to +70
-40 to +85
°C
Operating Junction Temperature Range
S C 431LC
S C 431LI
TJ
0 to +150
-40 to +150
°C
Storage Temperature Range
TSTG
-65 to +150
°C
Lead Temperature (Soldering) 10 seconds
TLEAD
300
°C
ESD Rating (Human Body Model)
V ESD
2
kV
Electrical Characteristics
Unless specified:TA = 25°C. Values in bold apply over full operating ambient temperature range.
SC431L 0.25%
Parameter
Reference Voltage
SC431L 0.5%
Symbol
Condition
Min
Typ
Max
Min
Typ
Max
Units
VREF
VZ = VREF, IZ = 10mA(1)
1.237
1.240
1.243
1.234
1.240
1.246
V
1.256
1.222
1.224
1.258
VREF Temp Deviation
V D EV
VZ = VREF, IZ = 10mA(1)
10
25
10
25
mV
Ratio of Change in
∆VREF
∆VZ
IZ = 10mA, ∆VZ = 16V to VREF
-1.0
-2.7
-1.0
-2.7
mV/V
Reference Input
Current
IREF
R1 = 10kΩ, R2 = ∞,
IZ = 10mA(2)
0.15
0.5
0.15
0.5
µA
IREF Temperature
Deviation
IREF(DEV)
R1 = 10kΩ, R2 = ∞,
IZ = 10mA(2)
0.1
0.4
0.1
0.4
µA
IZ (OFF)
VREF = 0V, VZ = 6V(3)
0.125
0.150
0.125
0.150
µA
VREF = 0V, VZ = 16V(3)
0.135
0.150
0.135
0.150
VREF to Change in VZ
Off-State Cathode
Current
 2008 Semtech Corp.
2
www.semtech.com
SC431L
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Unless specified:TA = 25°C. Values in bold apply over full operating ambient temperature range.
(Continued from page 2)
Parameter
Dynamic Output
Impedance
Minimum Operating
Current
SC431L 0.25%
Symbol
Condition
rZ
IZ (MIN)
Min
Typ
Max
f < 1kHz, VZ = VREF
IZ = 100µA to 100mA(1)
0.05
VZ = VREF(1)
20
Typ
Max
Units
0.15
0.05
0.15
Ω
100
20
100
µA
S C 431L 1%
Parameter
Reference Voltage
SC431L 0.5%
Min
S C 431L 2%
Symbol
Condition
Min
Typ
Max
Min
Typ
Max
Units
VREF
VZ = VREF, IZ = 10mA(1)
1.228
1.240
1.252
1.215
1.240
1.265
V
1.265
1.200
1.215
1.280
VREF Temp Deviation
V D EV
VZ = VREF, IZ = 10mA(1)
10
25
10
35
mV
Ratio of Change in
∆VREF
∆VZ
IZ = 10mA, ∆VZ = 16V to VREF
-1.0
-2.7
-1.0
-2.7
mV/V
Reference Input
Current
IREF
R1 = 10kΩ, R2 = ∞,
IZ = 10mA(2)
0.15
0.5
0.15
0.5
µA
IREF Temperature
Deviation
IREF(DEV)
R1 = 10kΩ, R2 = ∞,
IZ = 10mA(2)
0.1
0.4
0.1
0.4
µA
IZ (OFF)
VREF = 0V, VZ = 6V(3)
0.125
0.150
0.125
0.150
µA
VREF = 0V, VZ = 16V(3)
0.135
0.150
0.135
0.150
rZ
f < 1kHz, VZ = VREF
IZ = 100µA to 100mA(1)
0.05
0.15
0.05
0.15
Ω
IZ (MIN)
VZ = VREF(1)
20
100
20
100
µA
VREF to Change in VZ
Off-State Cathode
Current
Dynamic Output
Impedance
Minimum Operating
Current
Notes:
(1) See Test Circuit 1 on page 4.
(2) See Test Circuit 2 on page 4.
(3) See Test Circuit 3 on page 4.
Recommended Operating Conditions
Cathode Voltage, VZ
Cathode Current, IZ
 2008 Semtech Corp.
Min
Max
Symbol
VREF
16
V
100µA
100
mA
3
www.semtech.com
SC431L
POWER MANAGEMENT
Test Circuits
Test Circuit 1
VZ = VREF
Test Circuit 3
Off-State
Test Circuit 2
VZ > VREF
Pin Configurations
SOT-23-5 (Top View)
SOT-23-3 (Top View)
Block Diagram
 2008 Semtech Corp.
Symbol
4
www.semtech.com
SC431L
POWER MANAGEMENT
Ordering Information
P ackag e
TJ (°C)
SOT-23-3(1)(2)
0 to +150
-40 to +150
SOT-23-5(1)(2)
0 to +150
-40 to +150
Tolerance
0.25%
0.5%
1.0%
2.0%
SC431LCSK-.25TR
SC431LCSK-.5TR
SC431LCSK-1TR
SC431LCSK-2TR
SC431LCSK-25TRT
SC431LCSK-.5TRT
SC431LCSK-1TRT
SC431LCSK-2TRT
SC431LISK-.25TR
SC431LISK-.5TR
SC431LISK-1TR
SC431LISK-2TR
SC431LISK-.25TRT
SC431LISK-.5TRT
SC431LISK-1TRT
SC431LISK-2TRT
SC431LC5SK.25TR
SC431LC5SK-.5TR
SC431LC5SK-1TR
SC431LC5SK-2TR
SC431LC5SK25TRT
SC431LC5SK.5TRT
SC431LC5SK-1TRT
SC431LC5SK-2TRT
SC431LI5SK.25TR
SC431LI5SK-.5TR
SC431LI5SK-1TR
SC431LI5SK-2TR
SC431LI5SK25TRT
SC431LI5SK.5TRT
SC431LI5SK-1TRT
SC431LI5SK-2TRT
Notes:
(1) Only available in tape and reel packaging. A reel contains 3000 devices.
(2) “T” at end of part number indicates “lead free”. This product is fully WEEE and RoHS compliant.
Marking Information
SOT-23-3 (Top View only)
(0 to +150°C)
31L
SOT-23-3 (Top View only)
(-40 to +150°C)
3LI
SOT-23-5 (Top View)
(-40 to +150°C)
SOT-23-5 (Top View)
(0 to +150°C)
L5I
431L
SOT-23-5 (Bottom View)
SOT-23-5 (Bottom View)
yyww
yyww
yyww = Datecode,
Example: (0115)
 2008 Semtech Corp.
5
yyww = Datecode,
Example: (0015)
www.semtech.com
SC431L
POWER MANAGEMENT
Typical Characteristics
300
Cathode Current vs.
Cathode Current vs.
Cathode Voltage
Cathode Voltage
150
VZ = VREF
VZ = VREF
o
o
TA = 25 C
200
50
IZ (mA)
100
IZ (µA)
TA = 25 C
100
0
0
-100
-50
-200
-100
-300
-150
-1
-0.5
0
0.5
1
1.5
-1.5
-1
-0.5
0
VZ (V)
VZ (V)
1
Reference Voltage vs.
Reference Input Current vs.
Junction Temperature
Junction Temperature
1.248
1.5
150
IZ = 10mA
R1 = 10kΩ
R2 = ∞
IZ = 10mA
1.246
125
IREF (nA)
1.244
VREF (V)
0.5
1.242
1.240
100
IZ = 60µA
1.238
75
1.236
50
1.234
-50
-25
0
25
50
75
100
125
-50
150
-25
0
25
50
75
100
Ratio of Delta Reference Voltage to Delta Cathode
Off-State Cathode Current
Voltage vs. Junction Temperature
vs. Junction Temperature
1.2
1.1
250
IZ = 10mA
∆VZ = 16V to VREF
150
VZ = 16V
VREF = 0V
200
0.9
0.8
0.7
IZ(off) (nA)
VREF / VZ (-mV/V)
1.0
125
TJ (°C)
TJ (°C)
0.6
0.5
150
100
0.4
0.3
50
0.2
0.1
0.0
VZ = 6V
0
-50
-25
0
25
50
75
100
125
150
-50
TJ (°C)
 2008 Semtech Corp.
-25
0
25
50
75
100
125
150
TJ (°C)
6
www.semtech.com
SC431L
POWER MANAGEMENT
Typical Characteristics (Cont.)
Reference Impedance vs.
Reference Impedance
Junction Temperature
vs. Frequency
100
0.50
IZ = 0.1 to 100 mA
VZ = VREF
f < 1 kHz
0.45
0.40
TA = 25°C
10
0.35
rZ (Ω)
rZ ( )
0.30
0.25
0.20
1
0.15
0.1
0.10
0.05
0.00
-50
-25
0
25
50
75
100
125
0.01
1.E+03
150
1.E+04
TJ (°C)
1.E+05
1.E+06
1.E+07
f (Hz)
Test Circuit - Small-Signal Gain and Phase
Small-Signal Gain and Phase Shift
80
-180
70
-225
60
-270
50
-315
40
-360
30
-405
20
-450
10
-495
0
-540
-10
-585
-20
Phase Shift (deg)
AV (dB)
vs. Frequency
-630
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06
f (Hz)
Test Circuit - Stability
Stability Boundary Condition For Shunt Regulation
vs. Cathode Current and Load Capacitance
3.5
TA = 25°C
3.0
Stable
Stable
IZ (mA)
2.5
2.0
1.5
VZ = VREF
1.0
0.5
0.0
0.001
VZ = 2V
0.01
0.1
1
10
CL (µF)
 2008 Semtech Corp.
7
www.semtech.com
SC431L
POWER MANAGEMENT
Applications Information - Stability
Selection of load capacitance when using SC431L as
a shunt regulator
When the SC431L is used as a shunt regulator, two
options for selection of CL (see diagram on page 7) are
recommended for optimal stability:
1) No load capacitance across the device, decouple at
the load.
2) Large capacitance across the device, optional
decoupling at the load.
The reason for this is that SC431L exhibits instability with
capacitances in the range of 10nF to 1µF (approx.) at
light cathode currents (up to 3mA typical). The device is
less stable the lower the cathode voltage has been set
for. Therefore while the device will be perfectly stable
operating at a cathode current of (say) 10mA with a 0.1µF
capacitor across it, it will oscillate transiently during startup as the cathode current passes through the instability
region. Selecting a very low (or preferably, no)
capacitance, or alternatively a high capacitance (such
as 10µF) will avoid this issue altogether. Since the user
will probably wish to have local decoupling at the load
anyway, the most cost effective method is to use no
capacitance at all directly across the device. PCB trace/
via resistance and inductance prevent the local load
decoupling from causing the oscillation during the
transient start-up phase. Note: if the SC431L is located
right at the load, so the load decoupling capacitor is
directly across it, then this capacitor will have to be ≤
1nF or ≥ 10µF.
 2008 Semtech Corp.
8
www.semtech.com
SC431L
POWER MANAGEMENT
Outline Drawing - SOT-23-3
D
A
DIM
e1
3
1
E
2
bxN
bbb
e
.015
0°
.037
.114
.093
.051
.075
.037
.020
.022
3
.004
.008
.044
.004
.040
.020
.007
.120
.104
.055
.024
8°
0.89
1.12
0.01
0.10
0.88 0.95 1.02
0.51
0.30
0.18
0.08
2.80 2.90 3.04
2.10 2.37 2.64
1.20 1.30 1.40
1.90 BSC
0.95 BSC
0.40 0.50 0.60
(0.55)
3
0°
8°
0.10
0.20
C A B
A2
A
.035
.000
.035
.012
.003
.110
.082
.047
A
A1
A2
b
c
D
E
E1
e
e1
L
L1
N
0
aaa
bbb
B
E1
DIMENSIONS
INCHES
MILLIMETERS
MIN NOM MAX MIN NOM MAX
aaa C
3X
SEATING PLANE
A1
C
H
GAUGE
PLANE
SEATING
PLANE
0
0.25
C
L
L1
SEE DETAIL A
SIDE VIEW
c
DETAIL A
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. DATUMS -A- AND -B-
TO BE DETERMINED AT DATUM PLANE -H-
3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS
OR GATE BURRS.
Land Pattern - SOT-23-3
X
Y
DIM
Z
G
C
Y
C
E
E1
G
X
Y
Z
DIMENSIONS
INCHES
MILLIMETERS
(.087)
.037
.075
.031
.039
.055
.141
(2.20)
0.95
1.90
0.80
1.00
1.40
3.60
E
E1
NOTES:
1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
2. REFERENCE IPC-SM-782A.
Note:
(1) Grid placement courtyard is 8 x 8 elements (4mm x 4mm) in accordance with the international grid detailed in
IEC Publication 97.
 2008 Semtech Corp.
9
www.semtech.com
SC431L
POWER MANAGEMENT
Outline Drawing - SOT-23-5
A
DIM
e1
2X E/2
D
A
A1
A2
b
c
D
E1
E
e
e1
L
L1
N
01
aaa
bbb
ccc
N
EI
1
E
2
ccc C
2X N/2 TIPS
e
B
D
aaa C
A2
DIMENSIONS
INCHES
MILLIMETERS
MIN NOM MAX MIN NOM MAX
.035
.000
.035
.010
.003
.110
.060
-
.045
-
.057
.006
.051
.020
.009
.118
.069
.114
.063
.110 BSC
.037 BSC
.075 BSC
.012 .018 .024
(.024)
5
0°
10°
.004
.008
.008
0.90
0.00
.90
0.25
0.08
2.80
1.50
-
1.15
-
1.45
0.15
1.30
0.50
0.22
3.00
1.75
2.90
1.60
2.80 BSC
0.95 BSC
1.90 BSC
0.30 0.45 0.60
(0.60)
5
0°
10°
0.10
0.20
0.20
A
SEATING PLANE
A1
C
H
bxN
bbb
C A-B D
c
GAGE
PLANE
0.25
L
01
(L1)
SEE DETAIL
A
DETAIL
A
SIDE VIEW
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS
OR GATE BURRS.
Land Pattern - SOT-23-5
X
DIM
(C)
G
Z
Y
P
DIMENSIONS
MILLIMETERS
INCHES
(.098)
.055
.037
.024
.043
.141
C
G
P
X
Y
Z
(2.50)
1.40
0.95
0.60
1.10
3.60
NOTES:
1.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805)498-2111 FAX (805)498-3804
 2008 Semtech Corp.
10
www.semtech.com