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150mA Ultra Low Dropout Regulator with Undervoltage Flag
POWER MANAGEMENT Description
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 75A 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. 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. 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.
SC1457
Features
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 110VRMS 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)
Applications
Battery Powered Systems Cellular Telephones Cordless Telephones Personal Digital Assistants Portable Instrumentation Modems PCMCIA cards
Typical Application Circuit
U1 VIN C1 1uF 1 3 IN EN
SC1457 OUT GND 2 FLG 5 4 R1 100k C2 1uF UNDERVOLTAGE FLAG VO
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 Input Supply Voltage I/O Pin Voltages Thermal Resistance Junction to Ambient Thermal Resistance Junction to Case Operating Ambient Temperature Range Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering) 10 seconds ESD Rating (Human Body Model)
Symbol VIN VEN, VFLG J A J C TA TJ TSTG TLEAD V ESD
Maximum -0.6 to +7 -0.6 to VIN 256 81 -40 to +85 -40 to +125 -60 to +150 300 2
Units V V C/W C/W C C C C kV
Electrical Characteristics
Unless specified: VIN = VOUT + 1V, VEN = VIN, IOUT = 100A, TA = 25C. Values in bold apply over full operating ambient temperature range.
Parameter IN Supply Voltage Range Supply Current
Symbol
Conditions
Min
Typ
Max
Units
VIN IQ IOUT = 0mA to150mA
2.25 75
6.50 130 160
V A
VIN = 6.5V, VEN = 0V
0.1
1.0 1.5
A
OUT Output Voltage (1) VOUT IOUT = 1mA 0mA IOUT 150mA, VOUT +1V VIN 5.5V Line Regulation (1)(2) REG(LINE) (VOUT(NOM) + 0.1V) VIN 5.5V, IOUT = 1mA -1.5% -2.0% 2.5 VOUT +1.5% +2.0% 10 12 Load Regulation (1) REG(LOAD) IOUT = 0.1mA to 150mA -3 -10 -20 mV mV V
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SC1457
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless specified: VIN = VOUT + 1V, VEN = VIN, IOUT = 100A, TA = 25C. Values in bold apply over full operating ambient temperature range.
Parameter Out (Cont.) Current Limit Dropout Voltage(1)(3)
Symbol
Conditions
Min
Typ
Max
Units
ILIM VD IOUT = 1mA IOUT = 50mA
400 1 50 65 75 IOUT = 100mA 100 125 155 IOUT = 150mA 150 190 230
mA mV mV
mV
mV
Output Voltage Noise
en
10Hz to 100kHz, IOUT = 50mA, COUT = 1F 10Hz to 100kHz, IOUT = 50mA, COUT = 100F
135 110 60
VRMS
Power Supply Rejection Ratio EN Enable Input Threshold
PSRR
f = 120Hz
dB
VIH VIL
2.25V VIN 6.5V 2.25V VIN 6.5V 0V VEN VIN
1.6 0.4 -0.5 0 +0.5
V
Enable Input Bias Current(4) FLG Flag Threshold
IEN
A
VTH(FLG)
Under voltage condition (below nominal)
-4 -4
-6
-8 -12 0.4
%
Output Logic Low Voltage Flag Leakage Current Over Temperature Protection High Trip Level Hysteresis
V F LG IFLG
IFLG = 1mA, undervoltage condition Flag OFF, VFLG = 0V to 6.5V -1 0.1
V A
+1
THI THYST
150 20
C 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
Top View
Ordering Information
Part Number SC1457ISK-X.XTR(1) SC1457ISKX.XTRT(1)(4) SC1457ITSK-XXTR(1) SC1457ITSKXXTRT(1)(4) SC1457EVB(3) TSOT-23-5(2) N/A SOT-23-5(2) P ackag e
(SOT-23-5 & TSOT-23-5)
Block Diagram
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.
Pin Descriptions
Pin 1 2 3 4 5 Pin Name IN GND EN F LG OUT Pin Function Input pin Ground pin. Can be used for heatsinking if needed. Active high enable pin. Connect VIN if not being used. Error Flag. Open drain output. Active low indicates an output undervoltage condition. Regulator output sourcing up to 150mA.
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SC1457
POWER MANAGEMENT Marking Information
Top Mark Bottom Mark
x7XX
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
yyww = Date code (example: 0008 for week 8 of 2000)
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 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. 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 0.1A 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.
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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. The SC1457 includes thermal shutdown circuitry to turn off the device if T J exceeds 150C (typical), with the device remaining off until TJ drops by 20C (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. Component Selection - General Output capacitor - Semtech recommends a minimum capacitance of 1F at the output with an equivalent series resistance (ESR) of < 1 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. Input capacitor - Semtech recommends the use of a 1F 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 100k for this resistor to ensure that this pin is high even under worst-case flag pin leakage conditions of 1A when off.
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SC1457
POWER MANAGEMENT Applications Information (Cont.)
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 )
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 256C/W. Thus no additional heatsinking is required for this example. 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 JA to approximately 130C/W and T J(MAX) for the example above to approximately 100C 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. Layout Considerations While layout for linear devices is generally not as critical as for a switching application, careful attention to detail will ensure reliable operation. 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. 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.
(1)
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 = 85C Inserting these values into equation (2) gives us:
PD( MAX ) = (3.465 - 2.744 ) * 0.150 = 108mW
Using this figure, we can calculate the maximum thermal impedance allowable to maintain TJ 125C:
JA (MAX ) =
(T
J(MAX )
- TA (MAX ) )
PD(MAX )
=
(125 - 85) = 370C / W
0.108
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SC1457
POWER MANAGEMENT Typical Characteristics
Quiescent Current vs. Junction Temperature vs. Input Voltage
120 IOUT = 150mA 100 80 IQ (A) VIN = 3.8V 60 40 20 0 -50 -25 0 25 TJ (C) 50 75 100 125 IQ(OFF) (nA) VIN = 6.5V 200 175 150 125 100 75 50 25 0 -50 -25 0 25 TJ (C) 50 75 100 125
Off-State Quiescent Current vs. Junction Temperature
VIN = 6.5V VEN = 0V
Output Voltage vs. Junction Temperature vs. Output Current
0.00 IOUT = 1mA -0.05 VOUT Deviation (%) -0.10 -0.15 100mA IOUT 150mA -0.20 -0.25 VIN = VOUT + 1V -0.30 -50 -25 0 25 TJ (C) 50 75 100 125 0 10 8 6 4 2 12
Line Regulation vs. Junction Temperature vs. Input Voltage Change
IOUT = 1mA
REGLINE (mV)
IOUT = 50mA
VIN = VOUT + 1V to 6.5V
VIN = VOUT + 1V to 5.5V
-50
-25
0
25 TJ (C)
50
75
100
125
Load Regulation vs. Junction Temperature
10 9 8 7 REGLOAD (mV) ILIM (A) 6 5 4 3 2 1 0 -50 -25 0 25 TJ (C) 50 75 100 125 VIN = VOUT + 1V IOUT = 0.1mA to 150mA 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40
Current Limit vs. Junction Temperature vs. Input Voltage
VIN = 6.5V
VIN = 3.8V
-50
-25
0
25 TJ (C)
50
75
100
125
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SC1457
POWER MANAGEMENT Typical Characteristics (Cont.)
Dropout Voltage vs. Junction Temperature vs. Output Current
200 175 150 125 VD (mV) 100 75 50 25 0 -50 -25 0 25 TJ (C) 50 75 100 125 IOUT = 50mA VD (mV) IOUT = 150mA 200 175 150 125 100 75 50 25 0 0 25 50 75 IOUT (mA) 100 125 150 Top to bottom: TJ = 125C TJ = 25C TJ = -40C
Dropout Voltage vs. Output Current vs. Junction Temperature
Enable Input Threshold Voltage vs. Junction Temperature vs. Input Voltage
1.6 1.4 1.2 VEN (V) 1.0 0.8 VIL @ VIN = 3.8V 0.6 0.4 -50 -25 0 25 TJ (C) 50 75 100 125 -4.0 -4.5 VTH(FLG) (% below V OUT(NOM)) VIH @ VIN = 6.5V VIH @ VIN = 3.8V -5.0 -5.5 -6.0 -6.5 -7.0 -7.5 -8.0
Flag Threshold Voltage vs. Input Voltage vs. Output Voltage
VOUT = 1.5V
VIL @ VIN = 6.5V
VOUT = 3.3V
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
VIN (V)
Flag Threshold Voltage vs. Junction Temperature vs. Output Voltage
-4.0 -4.5 VTH(FLG) (% below V OUT(NOM)) -5.0 VFLG (mV) -5.5 -6.0 -6.5 -7.0 -7.5 -8.0 -50 -25 0 25 TJ (C) 50 75 100 125 VOUT = 3.3V VOUT = 1.5V 200 175 150 125 100 75 50
Flag Voltage vs. Junction Temperature vs. Flag Current
VIN = 4.3V
IFLG = 10mA
IFLG = 1mA 25 0 -50 -25 0 25 TJ (C) 50 75 100 125
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SC1457
POWER MANAGEMENT Typical Characteristics (Cont.)
Reverse Battery Protection vs. Junction Temperature
5.0 4.5 4.0 3.5 I(REV BAT) (mA) 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -50 -25 0 25 TJ (C) 50 75 100 125 VIN = VEN = -6.5V
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SC1457
POWER MANAGEMENT Evaluation Board Schematic
J1 RIPPLE MON J2 IN MON J3 IN
1 C1 C2 R4 3
U1 IN EN GND 2
SC1457 OUT FLG
5 R1 4 C3 C4 R2 R3
J4 OUT MON
J5 EN J8 1 2 3 EN
J6 1 2 IQ MON C5 J7 FLG
J10 GND
J11 GND
J12 GND
J13 GND
J14 GND
J15 GND J16 1 2 3 LOAD DRV EN
J9 LOAD DRV 1 2 3 4
Q1 S S S G Si4410 D D D D 8 7 6 5
Evaluation Board Bill of Materials
Quantity 3 2 1 3 1 1 1 2 1 6 1 1 1 1 1 1
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Reference C 1, C 4, C 5 C 2, C 3 J1 J2 - J4 J5 J6 J7 J8 , J1 6 J9 J1 0 - J1 5 Q1 R1 R2 R3 R4 U1
Part/Description Not placed 1F ceramic BNC socket Test pin Test pin Header, 2 pin Test pin Header, 3 pin Test pin Test pin S i 4410 100k, 1/10W Not placed See next page 10k, 1/10W SC1457ISK-X.X or SC1457ITSK-XX
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Vendor
Notes
Murata Various Various Various Various Various Various Various Various Vishay Various
GRM42-6X7R105K10 VOUT ripple monitor Red White
Yellow
Orange Black
Various Various Semtech
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SC1457
POWER MANAGEMENT Evaluation Board Gerber Plots
Top Copper
Output Voltage Option (V) 1.5 1.8 2.5 2.7 2.8 2.9 3.0 3.1 3.2 3.3 R3 Value/Siz e 10/0.5W 12/0.5W 16/0.5W 18/0.5W 18/0.5W 18/0.5W 20/0.5W 20/0.5W 22/0.5W 22/0.5W
Bottom Copper
Top Silk Screen
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SC1457
POWER MANAGEMENT Outline Drawing - SOT-23-5
A e1 N
EI
DIM
D
A A1 A2 b c D E1 E e e1 L L1 N 01 aaa bbb ccc A
DIMENSIONS MILLIMETERS INCHES MIN NOM MAX MIN NOM MAX
.035 .000 .035 .010 .003 .110 .060 .045 .057 .006 .051 .020 .009 .118 .069 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
2X E/2
E
1 ccc C
2X N/2 TIPS
2
e B D
aaa C
A2 SEATING PLANE
.114 .063 .110 BSC .037 BSC .075 BSC .012 .018 .024 (.024) 5 0 10 .004 .008 .008
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
C
A1 bxN
H
bbb
C A-B D
GAGE PLANE 0.25 L (L1)
c
01
SEE DETAIL SIDE VIEW
A
DETAIL
A
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
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SC1457
POWER MANAGEMENT Land Pattern - SOT-23-5 & TSOT-23-5
X
DIM
(C) G Y P Z 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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