SEMTECH SC1457ISKX.XTRT

SC1457
150mA Ultra Low Dropout
Regulator with Undervoltage Flag
POWER MANAGEMENT
Description
Features
The SC1457 is a low dropout linear regulator that
operates from a +2.25V to +6.5V input range and
delivers up to 150mA. A PMOS pass transistor allows
the low 75µA supply current to remain independent of
load, making these devices ideal for battery operated
portable equipment such as cellular phones, cordless
phones and personal digital assistants.
‹ Guaranteed 150mA output current
‹ Error flag indicates output undervoltage fault
‹ 2% output accuracy guaranteed over line, load and
temperature
‹ Very small external components - designed to work
with ceramic capacitors
Low 110µVRMS output noise
Very low supply current
Thermal overload protection
Reverse battery protection
Low power shutdown
Full industrial temperature range
Very low profile packaging available (1mm max.
height)
‹ Surface mount packaging (SOT-23-5 and
TSOT-23-5)
‹
‹
The SC1457 has very low dropout voltage (typically 1.1mV
at light loads and 150mV at 150mA) with better than ‹
1.5% initial output voltage accuracy. It has a logic ‹
compatible enable control input and an internal output ‹
‹
undervoltage monitor.
‹
Designed especially for hand held, battery powered
devices, the SC1457 can be switched by a CMOS or TTL
compatible logic signal. When disabled, power
consumption drops nearly to zero. Other features include
short circuit protection, thermal shutdown protection and
reverse battery protection.
Applications
‹
‹
The SC1457 is available in several fixed voltages in the
‹
tiny 5 lead SOT-23 package and the ultra low profile 5
‹
lead TSOT-23.
‹
‹
‹
Battery Powered Systems
Cellular Telephones
Cordless Telephones
Personal Digital Assistants
Portable Instrumentation
Modems
PCMCIA cards
Typical Application Circuit
SC1457
U1
1
VIN
C1
1uF
3
IN
EN
OUT
GND
FLG
5
VO
R1
4
100k
C2
1uF
UNDERVOLTAGE FLAG
2
Revision: November 10, 2004
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SC1457
POWER MANAGEMENT
Absolute Maximum Ratings
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified
in the Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device
reliability.
Parameter
Symbol
Maximum
Units
VIN
-0.6 to +7
V
VEN, VFLG
-0.6 to VIN
V
Thermal Resistance Junction to Ambient
θJ A
256
°C/W
Thermal Resistance Junction to Case
θJ C
81
°C/W
Operating Ambient Temperature Range
TA
-40 to +85
°C
Operating Junction Temperature Range
TJ
-40 to +125
°C
Storage Temperature Range
TSTG
-60 to +150
°C
Lead Temperature (Soldering) 10 seconds
TLEAD
300
°C
ESD Rating (Human Body Model)
V ESD
2
kV
Input Supply Voltage
I/O Pin Voltages
Electrical Characteristics
Unless specified: VIN = VOUT + 1V, VEN = VIN, IOUT = 100µA, TA = 25°C. Values in bold apply over full operating ambient temperature range.
Parameter
Symbol
Conditions
Min
Typ
Max
Units
6.50
V
130
µA
IN
Supply Voltage Range
VIN
Supply Current
IQ
2.25
IOUT = 0mA to150mA
75
160
VIN = 6.5V, VEN = 0V
0.1
1.0
µA
1.5
OUT
Output Voltage (1)
Line Regulation (1)(2)
VOUT
REG(LINE)
IOUT = 1mA
-1.5%
0mA ≤ IOUT ≤ 150mA, VOUT +1V ≤ VIN ≤ 5.5V
-2.0%
(VOUT(NOM) + 0.1V) ≤ VIN ≤ 5.5V, IOUT = 1mA
VOUT
+1.5%
V
+2.0%
2.5
10
mV
12
Load Regulation (1)
REG(LOAD)
IOUT = 0.1mA to 150mA
-3
-10
mV
-20
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SC1457
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Unless specified: VIN = VOUT + 1V, VEN = VIN, IOUT = 100µA, TA = 25°C. Values in bold apply over full operating ambient temperature range.
Parameter
Symbol
Conditions
Min
Typ
Max
Units
Out (Cont.)
Current Limit
ILIM
Dropout Voltage(1)(3)
VD
400
mA
IOUT = 1mA
1
IOUT = 50mA
50
mV
65
mV
75
IOUT = 100mA
100
125
mV
155
IOUT = 150mA
150
190
mV
230
Output Voltage Noise
Power Supply Rejection Ratio
en
10Hz to 100kHz, IOUT = 50mA, COUT = 1µF
135
µVRMS
10Hz to 100kHz, IOUT = 50mA, COUT = 100µF
110
PSRR
f = 120Hz
60
VIH
2.25V ≤ VIN ≤ 6.5V
VIL
2.25V ≤ VIN ≤ 6.5V
IEN
0V ≤ VEN ≤ VIN
-0.5
0
+0.5
µA
VTH(FLG)
Under voltage condition (below nominal)
-4
-6
-8
%
dB
EN
Enable Input Threshold
Enable Input Bias Current(4)
1.6
V
0.4
FLG
Flag Threshold
-4
Output Logic Low Voltage
V F LG
IFLG = 1mA, undervoltage condition
Flag Leakage Current
IFLG
Flag OFF, VFLG = 0V to 6.5V
-1
-12
0.1
0.4
V
+1
µA
Over Temperature Protection
High Trip Level
Hysteresis
THI
150
°C
THYST
20
°C
NOTES:
(1) Low duty cycle pulse testing with Kelvin connections required.
(2) VIN(MIN) = 2.25V.
(3) Defined as the input to output differential at which the output voltage drops 100mV below the value measured
at a differential of 1V. Not measurable on 1.5V and 1.8V parts due to minimum VIN constraints.
(4) Guaranteed by design.
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SC1457
POWER MANAGEMENT
Pin Configuration
Ordering Information
Part Number
Top View
P ackag e
SC1457ISK-X.XTR(1)
SC1457ISKX.XTRT(1)(4)
SOT-23-5(2)
SC1457ITSK-XXTR(1)
SC1457ITSKXXTRT(1)(4)
SC1457EVB(3)
TSOT-23-5(2)
N/A
Notes:
(1) Where X.X or XX denotes voltage options. Available
voltages are: 1.5V (1.5 or 15), 1.8V (1.8 or 18), 2.5V
(2.5 or 25), 2.7V (2.7 or 27), 2.8V (2.8 or 28), 2.9V (2.9
or 29), 3.0V (3.0 or 30), 3.1V (3.1 or 31), 3.2V (3.2 or
32) and 3.3V (3.3 or 33).
(2) Only available in tape and reel packaging. A reel
contains 3000 devices.
(3) Evaluation board for SC1457. Specify output voltage
option when ordering.
(4) Lead free product. This product is fully WEEE and
RoHS compliant.
(SOT-23-5 & TSOT-23-5)
Block Diagram
Pin Descriptions
Pin
Pin Name
1
IN
2
GND
3
EN
Active high enable pin. Connect VIN if not being used.
4
F LG
Error Flag. Open drain output. Active low indicates an output undervoltage condition.
5
OUT
Regulator output sourcing up to 150mA.
 2004 Semtech Corp.
Pin Function
Input pin
Ground pin. Can be used for heatsinking if needed.
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SC1457
POWER MANAGEMENT
Marking Information
Top Mark
Bottom Mark
x7XX
yyww
x = package (5 for SOT-23-5, T for TSOT-23-5)
7 = SC1457
XX = voltage option
(examples: 5731 for 3.1V option in SOT-23-5,
T728 for 2.8V option in TSOT-23-5)
yyww = Date code
(example: 0008 for week 8 of 2000)
The regulator has its own current limit circuitry to
ensure that the output current will not damage the
device during output short, overload or start-up. The
current limit is guaranteed to be greater than 400mA to
allow fast charging of the output capacitor and high
initial currents for DSP initialization.
Applications Information
Theory Of Operation
The SC1457 is intended for applications where very low
dropout voltage, low supply current and output voltage
monitoring are critical. It provides a very simple, low cost
solution that uses very little pcb real estate. Only two
external capacitors and one resistor are required for
operation.
The SC1457 includes thermal shutdown circuitry to turn
off the device if T J exceeds 150°C (typical), with the
device remaining off until TJ drops by 20°C (typical).
Reverse battery protection circuitry ensures that the
device cannot be damaged if the input supply is
accidentally reversed, limiting the reverse current to less
than 1.5mA.
The SC1457 contains a bandgap reference trimmed for
optimal temperature coefficient which is fed into the
inverting input of an error amplifier. The output voltage
of the regulator is divided down internally using a
resistor divider and compared to the bandgap voltage.
The error amplifier drives the gate of a low R DS(ON)
P-channel MOSFET pass device.
Component Selection - General
Output capacitor - Semtech recommends a minimum
capacitance of 1µF at the output with an equivalent
series resistance (ESR) of < 1Ω over temperature. While
the SC1457 has been designed to be used with ceramic
capacitors, it does not have to be used with ceramic
capacitors, allowing the designer a choice. Increasing the
bulk capacitance will further reduce output noise and
improve the overall transient response.
An active high enable pin (EN) allows the regulator to be
shut down. Pulling this pin low causes the device to
enter a very low power shutdown mode, where it will draw
typically 0.1µA from the input supply.
An open drain flag pin (FLG) is provided to signal
whenever the output voltage is 6% (typically) below
nominal. A tap is taken from the internal resistor divider
and compared to the bandgap voltage to determine if
the output voltage is above or below this level. The flag
pin pulls low whenever the output is out of specification.
An external pullup resistor is required for a high signal
when the flag pin is not pulling low. Since this circuitry is
powered from the input supply, the FLG pin will pull low
for output voltages all the way down to zero, unlike
external devices powered from the LDO output.
 2004 Semtech Corp.
Input capacitor - Semtech recommends the use of a
1µF ceramic capacitor at the input. This allows for the
device being some distance from any bulk capacitance
on the rail. Additionally, input droop due to load transients
is reduced, improving overall load transient response.
Flag pullup resistor - Semtech recommends a maximum
value of 100kΩ for this resistor to ensure that this pin is
high even under worst-case flag pin leakage conditions
of 1µA when off.
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SC1457
POWER MANAGEMENT
Applications Information (Cont.)
With the standard SOT-23-5/TSOT-23-5 Land Pattern
shown at the end of this datasheet, and minimum trace
widths, the thermal impedance junction to ambient for
SC1457ISK is 256°C/W. Thus no additional heatsinking
is required for this example.
Thermal Considerations
The worst-case power dissipation for this part is given
by:
PD(MAX ) = (VIN(MAX) − VOUT(MIN) )• IOUT(MAX ) + VIN(MAX ) • IQ(MAX )
(1)
The junction temperature can be reduced further (or
higher power dissipation can be allowed) by the use of
larger trace widths and connecting PCB copper to the
GND pin (pin 2), which connects directly to the device
substrate. Adding approximately one square inch of PCB
copper to pin 2 will reduce θ JA to approximately
130°C/W and T J(MAX) for the example above to
approximately 100°C for the SOT-23-5 package. The use
of multi layer boards with internal ground/power planes
will lower the junction temperature and improve overall
output voltage accuracy.
For all practical purposes, equation (1) can be reduced
to the following expression:
PD(MAX) = (VIN(MAX ) − VOUT(MIN) )• IOUT(MAX )
(2)
Looking at a typical application, 3.3V to 2.8V at 150mA:
VIN(MAX) = 3.3 + 5% = 3.465V
VOUT(MIN) = 2.8V - 2% = 2.744V
IOUT = 150mA
TA = 85°C
Layout Considerations
Inserting these values into equation (2) gives us:
While layout for linear devices is generally not as critical
as for a switching application, careful attention to detail
will ensure reliable operation.
PD( MAX ) = (3.465 − 2.744 ) • 0.150 = 108mW
1) Attaching the part to a larger copper footprint will
enable better heat transfer from the device, especially
on PCBs where there are internal ground and power
planes.
Using this figure, we can calculate the maximum thermal
impedance allowable to maintain TJ ≤ 125°C:
θ JA (MAX ) =
(T
J(MAX )
− TA (MAX ) )
PD(MAX )
=
(125 − 85) = 370°C / W
0.108
2) Place the input, output and bypass capacitors close
to the device for optimal transient response and device
behaviour.
3) Connect all ground connections directly to the ground
plane. If there is no ground plane, connect to a common
local ground point before connecting to board ground.
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SC1457
POWER MANAGEMENT
Typical Characteristics
Quiescent Current vs. Junction Temperature
Off-State Quiescent Current
vs. Input Voltage
vs. Junction Temperature
120
200
IOUT = 150mA
VIN = 6.5V
VIN = 6.5V
VEN = 0V
175
100
150
IQ(OFF) (nA)
IQ (µA)
80
VIN = 3.8V
60
40
125
100
75
50
20
25
0
0
-50
-25
0
25
50
75
100
125
-50
-25
0
25
TJ (°C)
vs. Output Current
vs. Input Voltage Change
12
-0.05
REGLINE (mV)
IOUT = 50mA
-0.15
100mA ≤ IOUT ≤ 150mA
-0.20
-0.25
IOUT = 1mA
8
VIN = VOUT + 1V to 6.5V
6
4
2
VIN = VOUT + 1V to 5.5V
VIN = VOUT + 1V
-0.30
0
-50
-25
0
25
50
75
100
125
-50
-25
0
25
TJ (°C)
50
75
100
125
TJ (°C)
Load Regulation vs.
Current Limit vs. Junction Temperature
Junction Temperature
vs. Input Voltage
0.90
VIN = VOUT + 1V
IOUT = 0.1mA to 150mA
0.85
8
0.80
7
0.75
6
0.70
ILIM (A)
REGLOAD (mV)
125
10
-0.10
9
100
Line Regulation vs. Junction Temperature
IOUT = 1mA
10
75
Output Voltage vs. Junction Temperature
0.00
VOUT Deviation (%)
50
TJ (°C)
5
4
0.65
0.60
3
0.55
2
0.50
1
0.45
0
VIN = 6.5V
VIN = 3.8V
0.40
-50
-25
0
25
50
75
100
125
-50
TJ (°C)
 2004 Semtech Corp.
-25
0
25
50
75
100
125
TJ (°C)
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SC1457
POWER MANAGEMENT
Typical Characteristics (Cont.)
Dropout Voltage vs. Junction Temperature
Dropout Voltage vs. Output Current
vs. Output Current
vs. Junction Temperature
200
200
175
175
150
150
IOUT = 150mA
125
VD (mV)
VD (mV)
125
100
75
100
75
50
Top to bottom:
TJ = 125°C
TJ = 25°C
TJ = -40°C
50
IOUT = 50mA
25
25
0
0
-50
-25
0
25
50
75
100
125
0
25
50
TJ (°C)
100
125
150
Enable Input Threshold Voltage vs. Junction
Flag Threshold Voltage vs. Input Voltage
Temperature vs. Input Voltage
vs. Output Voltage
1.6
-4.0
-4.5
1.4
VIH @ VIN = 6.5V
1.2
VIH @ VIN = 3.8V
1.0
VIL @ VIN = 6.5V
VTH(FLG) (% below V OUT(NOM))
VEN (V)
75
IOUT (mA)
0.8
VIL @ VIN = 3.8V
0.6
-5.0
VOUT = 1.5V
-5.5
-6.0
VOUT = 3.3V
-6.5
-7.0
-7.5
0.4
-8.0
-50
-25
0
25
50
75
100
125
2.0
2.5
3.0
3.5
4.0
TJ (°C)
4.5
5.0
5.5
6.0
Flag Threshold Voltage vs. Junction Temperature
Flag Voltage vs. Junction Temperature
vs. Output Voltage
vs. Flag Current
-4.0
200
-4.5
175
-5.0
VIN = 4.3V
150
VOUT = 1.5V
-5.5
VFLG (mV)
VTH(FLG) (% below V OUT(NOM))
6.5
VIN (V)
-6.0
VOUT = 3.3V
-6.5
IFLG = 10mA
125
100
75
-7.0
50
-7.5
25
IFLG = 1mA
-8.0
0
-50
-25
0
25
50
75
100
125
-50
TJ (°C)
 2004 Semtech Corp.
-25
0
25
50
75
100
125
TJ (°C)
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SC1457
POWER MANAGEMENT
Typical Characteristics (Cont.)
Reverse Battery Protection vs.
Junction Temperature
5.0
4.5
VIN = VEN = -6.5V
4.0
I(REV BAT) (mA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-50
-25
0
25
50
75
100
125
TJ (°C)
 2004 Semtech Corp.
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SC1457
POWER MANAGEMENT
Evaluation Board Schematic
J1
RIPPLE MON
J2
IN MON
J3
1
U1
SC1457
IN
OUT
EN
FLG
J4
5
R1
IN
C1
C2
R4
3
GND
2
J5
C3
C5
IQ MON
1
2
3
C4
R2
R3
OUT MON
J6
1
2
J8
EN
4
J7
FLG
EN
J10
GND
J11
GND
J12
GND
J13
GND
J14
GND
J9
LOAD DRV
J15
GND
Q1
1
2
3
4
J16
1
2
3
S
S
S
G
D
D
D
D
8
7
6
5
Si4410
LOAD DRV EN
Evaluation Board Bill of Materials
Quantity
Reference
Part/Description
Vendor
Notes
3
C 1, C 4, C 5
Not placed
2
C 2, C 3
1µF ceramic
Murata
GRM42-6X7R105K10
1
J1
BNC socket
Various
VOUT ripple monitor
3
J2 - J4
Test pin
Various
Red
1
J5
Test pin
Various
White
1
J6
Header, 2 pin
Various
1
J7
Test pin
Various
2
J8 , J1 6
Header, 3 pin
Various
1
J9
Test pin
Various
Orange
6
J1 0 - J1 5
Test pin
Various
Black
1
Q1
S i 4410
Vishay
1
R1
100kΩ, 1/10W
Various
1
R2
Not placed
1
R3
See next page
Various
1
R4
10kΩ, 1/10W
Various
1
U1
SC1457ISK-X.X or
SC1457ITSK-XX
Semtech
 2004 Semtech Corp.
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SC1457
POWER MANAGEMENT
Evaluation Board Gerber Plots
Top Copper
Bottom Copper
Output Voltage Option (V)
R3 Value/Siz e
1.5
10Ω/0.5W
1.8
12Ω/0.5W
2.5
16Ω/0.5W
2.7
18Ω/0.5W
2.8
18Ω/0.5W
2.9
18Ω/0.5W
3.0
20Ω/0.5W
3.1
20Ω/0.5W
3.2
22Ω/0.5W
3.3
22Ω/0.5W
 2004 Semtech Corp.
Top Silk Screen
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SC1457
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
MILLIMETERS
INCHES
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.
Outline Drawing - TSOT-23-5
 2004 Semtech Corp.
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SC1457
POWER MANAGEMENT
Land Pattern - SOT-23-5 & TSOT-23-5
X
DIM
(C)
G
Z
Y
P
C
G
P
X
Y
Z
DIMENSIONS
MILLIMETERS
INCHES
(.098)
.055
.037
.024
.043
.141
(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
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