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POWER MANAGEMENT Features

2.5MHz, 1.5A Synchronous Step Down Regulator
Description
The SC189 is a high efficiency, synchronous step-down regulator providing up to 1.5A output current in either an ultra-small 2mm x 2mm, low profile package or a low cost SOT23-5 package. The device requires only three external filter components for a complete step down regulator solution. The input voltage range is 2.9 to 5.5V with either factory programmed outputs from 1.0 to 3.3V or adjustable output via an external resistor divider. The converter operates at fixed 2.5MHz switching frequency allowing small L/C filtering components. The voltage mode architecture is compatible with chip inductors and capacitors for minimum PCB footprint and lowest overall system cost. Total footprint of 25mm2 can be achieved - making the SC189 the ideal solution for high density systems. Solution height of <1mm is also possible. Up to 93% efficiency is achieved with low RDS(ON) internal switches. PWM constant frequency operation ensures low output ripple across the load range. 100% duty-cycle provides 360mV dropout voltage at 1.5A which extends the minimum input voltage for 2.5V and 3.3V outputs. Excellent transient response is achieved with no external compensation components. The SC189 provides input under-voltage, output overvoltage, output short circuit and over-temperature protection to safeguard the device and system under fault conditions. The regulator provides integrated soft-start to minimize inrush currents. Standby quiescient current is less than 1A. The SC189 is available in SOT23-5 and a thermally enhanced 2mm x 2mm x 0.6mm MLPD-UT6 package rated from -40 to +85C.
SC189
VIN Range: 2.9 - 5.5V VOUT Options: 1.0 - 3.3V Up to 1.5A Output Current Ultra-Small Footprint, <1mm Height Solution 2.5MHz Switching Frequency Efficiency Up to 93% Low Output Noise Across Load Range Excellent Transient Response Start Up into Pre-Bias Output 100% Duty-Cycle Low Dropout Operation <1A Shutdown Current Internal Soft Start Input Under-Voltage Lockout Output Over-Voltage, Current Limit Protection Over-Temperature Protection Adjustable Output Voltage Available in SOT23-5 package and 2mm x 2mm x 0.6mm thermally enhanced MLPD-UT6 package -40 to +85C Temperature Range Fully WEEE and RoHS Compliant
Applications

Bluetooth Radios DSC and PMPs GPS Devices xDSL Systems POL Regulators Portable HDD Wireless LAN
Typical Application Circuit
SC189C
VIN 2.9V to 5.5V VIN CIN 10F EN LX VOUT GND L 1H
Total PCB Area ~25mm2
VOUT 1.20V/1.5A COUT 22F
L Chip
COUT
0805
SC189
CIN 0603
Actual Size
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SC189
Pin Configuration
NC EN VIN
1 2 3 6 5
Ordering Information
Device
TOP VIEW
Package & Description 2mm x 2mm x 0.6mm MLPD-UT6 SOT23-5 Evaluation Board for MLPD-UT6 - Standard Size (i.e., Wire Wound Inductor) Evaluation Board for MLPD-UT6 - Small Size (i.e., Chip Inductor) Evaluation Board for SOT23-5 - Standard Size (i.e., Wire Wound Inductor) Evaluation Board for SOT23-5 - Small Size (i.e., Chip Inductor)
VOUT GND LX
SC189xULTRT(2)(3)(4) SC189xSKTRT2)(3)(4) SC189xEVB(5)
T
4
2mm x 2mm x 0.6mm MLPD-UT6 JA = 60C/W(1)
SC189xEVB-1(5)
VIN GND EN
1
TOP VIEW
5
LX
SC189xEVB-2(5)
2
SC189xEVB-3(5)
4
3
VOUT
SOT23-5 JA = 90C/W(1)
Marking Information
FLx
Notes: (1) Measured in free convection, mounted on 10mm x 10mm, 2 layer FR4 PCB shown in figure 7 ( for MLPD-UT6 package) and figure 8 ( for SOT23-5 package) with copper of 1oz for each layer. (2) Available in tape and reel only. A reel contains 3,000 devices. (3) Available in lead-free package only. Device is WEEE and RoHS compliant. (4) "x" is the code of the output voltage. See Table 1 for the code. For example, the device number for VOUT= 1.20V is SC189CULTRT. (5) "x" is the code of the output voltage. See Table 1 for the code. For example, the EVB for MLPD-UT6 package with VOUT= 1.20V is SC189CEVB (Standard Size) or SC189CEVB-1 (Small Size).
Table 1: Available Output Voltages
Marking for 2mm x 2mm MLPD-UT 6 Lead Package: x = Code of the output voltage (Example: C for VOUT=1.20V) oyw = Pin 1 and Datecode (Reference Package Marking Design Guidelines, Appendix A)
Code for MLPD-UT6 A B C E F H L N T
Not Available
Code for SOT23-5 A B C
Not Available Not Available
VOUT(1) 1.00 1.10 1.20 1.28 1.30 1.50 1.80 2.00 2.50 2.70 3.30
Top Mark
Bottom Mark
189 x
Marking for SOT23, 5 Lead Package: x = Code of the output voltage (Example: C for VOUT=1.20V) yyww = Datecode (Example: 0852)
H L
Not Available
Y V Z
Z
Notes: (1) Contact factory for unavaliable output voltage options.
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SC189
Absolute Maximum Ratings
VIN Supply Voltage .................................... -0.3 to 6.0V LX Voltage .............. -1 to VIN+1V, -3V (20ns Max), 6V Max .................................... -0.3 to VIN+0.3V VOUT Voltage
Recommended Operating Conditions
VIN Supply Voltage .................................... 2.9 to 5.5V Maximum Output Current(3) ................................. 1.5A Temperature Range ................................. -40 to +85C
EN Voltage ........................................ -0.3 to VIN+0.3V Peak IR Reflow temperature ............................... 260C ESD Protection Level
(2)
Thermal Information
Thermal Resistance, Junction to Ambient(1) MLPD-UT6 Package .................................... 60C/W SOT23-5 Package .................................... 90C/W Maximum Junction Temperature ........................ +150C Storage Temperature Range ..................... -65 to +150 C
........................................
3kV
Exceeding the absolute maximum ratings may result in permanent damage to the device and/or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. NOTES: (1) Measured in free convection, mounted on 10mm x 10mm, 2 layer FR4 PCB shown in figure 7 ( for MLPD-UT6 package) and figure 8 ( for SOT235 package) with copper of 1oz for each layer. (2) Tested according to JEDEC standard JESD22-A114-B. (3) For SOT23-5 package, the limit of the maximum power dissiption shown in figure 2 may reduce the maximum output current.
Electrical Characteristics
Unless specified: VIN = 5.0V, CIN=10F, COUT=10F; L=2.2H; -40CParameter
Under-Voltage Lockout Output Voltage Tolerance(1) Current Limit VIN Supply Current VIN Shutdown Current High Side Switch Resistance
Symbol
UVLO VOUT ILIMIT IQ ISHDN RDSON_P
Conditions
Rising VIN Hysteresis VIN=3.6V to 5.0V; No Load Peak inductor current EN= VIN, No Load EN= GND ILX= 100mA, for MLPD-UT6 ILX= -100mA, for SOT23-5 ILX= -100mA, for MLPD-UT6 ILX= -100mA, for SOT23-5 VIN=5.5V; LX=0V; EN=GND VIN=5.5V; LX=5.0V; EN=GND VIN= 3.6 - 5.0V; IOUT=0A VIN= 5.0V; IOUT=10mA - 1.5A
Min
2.60
Typ
2.70 250
Max
2.80
Units
V mV
-2.5 2.0 7.5 1 0.13 0.15 0.10 0.125 1 -10 -1 1.0 1.0 2.0 2.5 100
+2.5
% A mA
10
A
Low Side Switch Resistance
RDSON_N
LX Leakage Current Line Regulation Load Regulation(2) Oscillator Frequency Soft-Start Time(2) EN Input High Current
ILK(LX) VLINE-REG VLOAD-REG FOSC TSS IEN_HI
10
A % %
3.0
MHz s
EN=VIN
-2.0
2.0
A
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SC189
Electrical Characteristics (continued)
Unless specified: VIN = 5.0V, CIN=10F, COUT=10F; L=2.2H; -40CParameter
EN Input Low Current EN Input High Threshold EN Input Low Threshold VOUT Over Voltage Protection(2) Thermal Shutdown Temperature (2) Thermal Shutdown Hysteresis (2)
Symbol
IEN_LO VEN_HI VEN_LO VOVP TSD TSD_HYS
Conditions
EN=GND
Min
-2.0 1.2
Typ
Max
2.0
Units
A V
0.4 115 Junction Temperature Junction Temperature +160 10
V % C C
Notes: (1) The "Output Voltage Tolerance" includes output voltage accuracy, voltage drift over temperature and the line regulation. (2) Guaranteed by design.
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SC189
Typical Characteristics
Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package.
Efficiency vs. Load Current (VOUT=1.5V) Efficiency
100% 95% 90% 100% 95% 90%
Efficiency Efficiency vs. Load Current (VOUT=3.3V)
VIN= 4.0V VIN= 5.0V
Efficiency (%)
85% 80% 75%
Efficiency (%)
85% 80% 75% 70% 65% 60%
VIN= 5.0V
VIN= 3.3V
70% 65% 60% 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A)
VOUT= 1.50V TA=25 C
VOUT= 3.30V TA=25 C
0.0 0.3 0.6 0.9 1.2 1.5
Output Current (A)
Efficiency Efficiency vs. Load Current (VIN=5.0V, VOUT=1.0V) 100% 95% 90%
Efficiency vs. Load Current (VIN=5.0V, VOUT=3.3V) Efficiency
100%
L=1071AS-2R2N (50m_typ) L=1071AS-1R0N (33m_typ)
L=1071AS-2R2N (50m_typ)
95% 90%
Efficiency (%)
Efficiency (%)
85% 80% 75% 70% 65% 60% 0.0 0.3
L=MDT2520-CR1R0M (60m_typ)
85%
L=1071AS-1R0N (33m_typ)
80%
L=MDT2520-CR1R0M (60m_typ)
75% 70% 65% 60%
VIN= 5.0V VOUT= 1.0V TA=25 C L=LQM2HPN1R0MG0 (55m_typ)
0.6 0.9 1.2 1.5
VIN= 5.0V VOUT= 3.3V TA=25 C
0.0 0.3
L=LQM2HP1R0MG0 (55m_typ)
0.6 0.9 1.2 1.5
Output Current (A)
Output Current (A)
Total Loss vs. LoadLosses Current (VOUT=1.5V)
800 800
Total Loss vs. LoadLosses Current (VOUT=3.3V)
VOUT= 3.30V TA=25 C
VOUT= 1.50V TA=25 C
600 Loss (mW)
VIN= 3.3V
Loss (mW)
600
400
400
VIN= 5.0V
200
200
VIN= 5.0V VIN= 4.0V
0 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A)
0 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A)
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SC189
Typical Characteristics (continued)
Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package.
Efficiency Efficiency vs. Load Current (VOUT=1.5V, SOT23-5) 100% 95% 90% Efficiency (%) 85% 80% 75% Efficiency (%) Efficiency Efficiency vs. Load Current (VOUT=3.3V, SOT23-5) 100%
VIN= 4.0V VIN= 5.0V
95% 90% 85% 80% 75% 70% 65% 60% 0.0 0.3 0.6 0.9 1.2 1.5 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A) Efficiency Efficiency vs. Load Current (SOT23-5) 100% 95% 90% Efficiency (%) 85% 80% 75% 70% 65% 100% Output Current (A) Efficiency Efficiency vs. Load Current (SOT23-5)
VIN= 5.0V
VIN= 3.3V
70% 65% 60%
VOUT= 1.50V TA=25 C
VOUT= 3.30V TA=25 C
VIN= 5.0V VOUT= 1.0V TA=25 C
L=1071AS-2R2 (50m_typ)
95% 90%
L=1071AS-2R2N (50m_typ)
L=1071AS-1R0 (33m_typ)
Efficiency (%) 85%
L=1071AS-1R0N (33m_typ)
80%
L=MDT2520-CR1R0M (60m_typ)
75% 70%
L=LQM2HPN1R0MG0 (55m_typ)
65%
L=MDT2520-CR1R0 (60m_typ)
60% 0.0 0.3 0.6 0.9 Output Current (A) 1.2 1.5 60% 0.0
VIN= 5.0V VOUT= 3.3V TA=25 C
0.3
L=LQM2HP1R0MG0 (55m_typ)
0.6 0.9 Output Current (A) 1.2 1.5
Losses Total Loss vs. Load Current (VOUT=1.5V, SOT23-5) 800
Total Loss vs. Load Current (VOUT=3.3V, SOT23-5) Losses
800
VOUT= 1.50V TA=25 C
600 Loss (mW)
VOUT= 3.30V TA=25 C VIN= 3.3V
Loss (mW) 600
400
400
VIN= 5.0V
200
200
VIN= 5.0V VIN= 4.0V
0 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A) 0 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A)
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SC189
Typical Characteristics (continued)
Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package.
RDSON (P & N) Variation over Line RDS(ON) Variation vs. Input Voltage 30% 25% 20% 15% Variation Variation 10% 5% 0% -5% -10% 2.5 3.0 3.5 4.0 Input Voltage (V) Switching Frequency Variation over Line Switching Frequency vs. Input Voltage 5% 4% 3% 2% Variation Variation 1% 0% -1% -2% -3% -4% -5% 2.5 3.0 3.5 4.0 Input Voltage (V) Line Regulation LineRegulation ove Line 1.0% 0.8% 0.6% 0.4% Regulation 0.2% 0.0% -0.2% -0.4% -0.6% -0.8% -1.0% 2.5 3.0 3.5 4.0 Input Voltage (V) 4.5 5.0 5.5 1.0% 0.8% 0.6% 4.5 5.0 5.5 1.0% 0.8% 4.5 5.0 5.5 20% 15% RDSON (P & N) Variation Over Temperature RDS(ON) Variation vs. Temperature
VIN= 5.0V ILX= 100mA
P-Channel
10% 5% 0% -5% -10%
N-Channel
ILX= 100mA TA= 25 C
N-Channel
-15% -20% -40 -15
P-Channel
10
35
60
85
Ambient Temperature ( C) Switching Frequency Variation Switching Frequency vs. Temperature
VOUT= 3.3V
0.6% 0.4% 0.2% 0.0% -0.2% -0.4% -0.6% -0.8% -1.0% -40 -15 10 35 60 85 Ambient Temperature ( C) Line Regulation over Temperature Line Regulation vs. Temperature
VOUT= 1.5V IOUT= 0A TA= 25 C
VIN= 5.0V IOUT= 0A
VOUT= 1.5V
Regulation
0.4% 0.2% 0.0% -0.2% -0.4%
VOUT= 3.3V IOUT= 0A TA= 25 C
-0.6% -0.8% -1.0% -40
VOUT= 1.5V IOUT= 0A
-15 10 35 60 85
Ambient Temperature ( C)
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SC189
Typical Characteristics (continued)
Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package.
Load Regulation Load Regulation (VOUT=1.5V) 1.0% 0.8% 0.6% Load Regulation Load Regulation 0.4% 0.2% 0.0% -0.2% -0.4% -0.6% -0.8% -1.0% 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A) 1.0% Load Regulation Load Regulation (VOUT=3.3V)
VOUT= 1.50V TA=25 C
0.8% 0.6%
VOUT= 3.30V TA=25 C VIN= 4.0V
VIN= 3.3V
0.4% 0.2% 0.0% -0.2% -0.4% -0.6%
VIN= 5.0V
VIN= 5.0V
-0.8% -1.0% 0.0 0.3 0.6 0.9 1.2 1.5 Output Current (A) UVLO Hysteresis Variation UVLO Hysteresis Variation 5% 4% 3% 2% Variation 1% 0% -1% -2% -3%
UVLOUVLO Rising Threshold Variation Rising Threshold Variation
1.0% 0.8% 0.6% 0.4% Variation 0.2% 0.0% -0.2% -0.4% -0.6% -0.8% -1.0% -40 -15 10 35 60 85 Ambient Temperature ( C)
IOUT= 0A
-4% -5% -40
IOUT= 0A
-15 10 35 60 85
Ambient Temperature ( C)
Dropout Voltage in 100% Duty Cycle Operation Dropout Voltage of 100% Duty Cycle Operation (MLP)
500 450 400
Dropout Voltage of 100% Duty Cycle Cycle Operation in 100% Duty Operation (SOT23-5) Dropout Voltage
500 450 400
Package: MLPD-UT6 TA= 25 C
Package: SOT23-5 TA= 25 C L= MDT2520-CR1R0M (DCR= 80m_max)
Dropout Voltage (mV)
Dropout Voltage (mV)
350 300 250 200 150 100 50 0 0.0
L= MDT2520-CR1R0M (DCR= 80m_max)
350 300 250 200 150 100 50 0
L= 1071AS-1R0 (DCR=40m_max)
L= 1071AS-2R2 (DCR=60m_max)
0.3
0.6
0.9
1.2
1.5
0.0
0.3
0.6
0.9
1.2
1.5
Output Current (A)
Output Current (A)
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SC189
Typical Waveforms
Circuit Conditions: VOUT=1.5V (SC189HULTRT); L= 2.2uH (TOKO: 1071AS-2R2M); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K).
Output Voltage Ripple (VOUT=1.5V) Output Voltage Ripple (VOUT=1.5V)
Output Voltage Ripple (VOUT=1.5V) Output Voltage Ripple (VOUT=1.5V)
10mV/div 500mA/div
VOUT ILX
10mV/div 500mA/div
VOUT
ILX
2V/div
VLX
2V/div
VLX
VIN=5.0V IOUT=0A
500ns/div
VIN=5.0V IOUT=1.5A
500ns/div
Output Voltage Ripple (VOUT=1.5V) Output Voltage Ripple (VOUT=1.5V)
Output Voltage Ripple (VOUT=1.5V) Output Voltage Ripple (VOUT=1.5V)
10mV/div 10mV/div 500mA/div
VOUT
VOUT
ILX
500mA/div
ILX
2V/div
VLX
2V/div
VLX
VIN=3.3V IOUT=0A
500ns/div
VIN=3.3V IOUT=1.5A
500ns/div
TransientTransient Response (VOUT=1.5V) Response (VOUT=1.5V; 0A to 0.5A)
Transient (V =1.5V; 0.5A to 1.0A) Transient Response Response (VOUT=1.5V) OUT
100mV/div
VOUT
100mV/div
VOUT
500mA/div
IOUT
500mA/div
IOUT
VIN=5.0V IOUT=0A to 0.5A
50s/div
VIN=5.0V IOUT=0.5A to 1A
50s/div
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SC189
Typical Waveforms (continued)
Circuit Conditions: VOUT=1.5V (SC189HULTRT); L= 2.2uH (TOKO: 1071AS-2R2); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K).
Start Up (VOUT=1.5V) Start Up (Enable)(VOUT=1.5V)
Start Up (VOUT=1.5V) Start Up (Enable)(VOUT=1.5V)
2V/div
VIN
2V/div
VIN
2V/div
VEN
2V/div
VEN
1V/div
VOUT
1V/div
VOUT
VIN=5.0V ROUT=1k
100s/div
VIN=5.0V ROUT=1
100s/div
Start Up (VOUT=1.5V), EN=VIN Start Up (Power up VIN) (VOUT=1.5V)
Start Up (VOUT=1.5V), EN=VIN Start Up (Power up VIN) (VOUT=1.5V)
2V/div
VIN
2V/div
VIN
500mV/div
VOUT
500mV/div
VOUT
VIN=5.0V ROUT=1k
200s/div
VIN=5.0V ROUT=1
200s/div
Start UpUp into Pre-Bias Output (VOUT=1.5V) Enable Start into Pre-Biased Output (Enable)
2V/div
ShutdownShutdown-Disable (Disable) (VOUT=1.5V)
VIN
2V/div 2V/div
VIN
2V/div
VEN
VEN
500mV/div
VOUT
500mV/div
VOUT
VIN=5.0V ROUT=1k
200s/div
VIN=5.0V ROUT=1.5
50s/div
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SC189
Typical Waveforms (continued)
Circuit Conditions: VOUT=3.3V (SC189ZULTRT); L= 2.2uH (TOKO: 1071AS-2R2); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K).
Output Voltage Ripple (VOUT=3.3V) Output Voltage Ripple (VOUT=3.3V)
Output Voltage Ripple (VOUT=3.3V) Output Voltage Ripple (VOUT=3.3V)
10mV/div 500mA/div
VOUT
ILX
10mV/div 500mA/div
VOUT ILX
2V/div
VLX
2V/div
VLX
VIN=5.0V IOUT=0A
500ns/div
VIN=5.0V IOUT=1.5A
500ns/div
TransientTransient Response (VOUT=3.3V) Response (VOUT=3.3V; 0A to 0.5A)
Transient (V =3.3V; 0.5A to 1.0A) Transient Response Response (VOUT=3.3V) OUT
100mV/div
VOUT
100mV/div
VOUT
500mA/div
IOUT
500mA/div
IOUT
VIN=5.0V IOUT=0A to 0.5A
50s/div
VIN=5.0V IOUT=0.5A to 1A
50s/div
Start Up (VOUT=3.3V) Start Up (Enable)(VOUT=3.3V)
Start Up (VOUT=3.3V) Start Up (Enable)(VOUT=3.3V)
5V/div
VIN
5V/div
VIN
2V/div
VEN
2V/div
VEN
1V/div
VOUT
1V/div
VOUT
VIN=5.0V ROUT=1k
200s/div
VIN=5.0V ROUT=2.2
200s/div
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SC189
Typical Waveforms (continued)
Circuit Conditions: VOUT=3.3V (SC189ZULTRT); L= 2.2uH (TOKO: 1071AS-2R2); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K).
Start Up (VOUT=3.3V), EN=VIN Start Up (Power up VIN) (VOUT=3.3V)
Start Up (VOUT=3.3V), EN=VIN Start Up (Power up VIN) (VOUT=3.3V)
2V/div
VIN
2V/div
VIN
1V/div
VOUT
1V/div
VOUT
VIN=5.0V ROUT=1k
200s/div
VIN=5.0V ROUT=2.2
200s/div
Start Up Up into Pre-BiasOutput (VOUT=3.3V)(Enable) Start into Pre-Biased Output (Enable)
Start Up into Pre-BiasedOutput (Power Up V ) Start Up into Pre-Bias Output (VOUT=3.3V)(Power Up)
IN
2V/div
VIN
2V/div
VIN
2V/div
VEN
1V/div
VOUT
1V/div
VOUT
VIN=5.0V ROUT=1k
200s/div
VIN=5.0V ROUT=1k
200s/div
Shutdown-Disable (V =3.3V) Shutdown (Disable) (VOUTOUT=3.3V)
Shutdown-Disable (V =3.3V) Shutdown (Disable) (VOUTOUT=3.3V)
5V/div
VIN
5V/div
VIN
2V/div
VEN
2V/div
VEN
2V/div
VOUT
2V/div
VOUT
VIN=5.0V ROUT=33
500s/div
VIN=5.0V ROUT=3.3
100s/div
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SC189
Typical Waveforms (continued)
Circuit Conditions: VOUT=1.0V (SC189AULTRT); L= 1uH (Murata: LQM2HPN1R0NG0L); CIN= 10uF/6.3V; COUT= 22uF/6.3V (Murata: GRM21BR60J226M).
Output Voltage Ripple (VOUT=1.0V) Output Voltage Ripple (VOUT=1.0V)
Output Voltage Ripple (VOUT=1.0V) Output Voltage Ripple (VOUT=1.0V)
10mV/div
VOUT
10mV/div
VOUT
500mA/div Offset: 0A
ILX
1A/div
ILX
2V/div
VLX
2V/div
VLX
VIN=3.3V IOUT=0A
500ns/div
VIN=3.3V IOUT=1.5A
500ns/div
Output Voltage Ripple (VOUT=1.0V) Output Voltage Ripple (VOUT=1.0V)
Output Voltage Ripple (VOUT=1.0V) Output Voltage Ripple (VOUT=1.0V)
10mV/div 500mA/div
VOUT
10mV/div 1A/div
VOUT
ILX
ILX
2V/div
VLX
2V/div
VLX
VIN=5.0V IOUT=0A
500ns/div
VIN=5.0V IOUT=1.5A
500ns/div
Transient Response (VOUT=1.0V) Transient Response (VOUT=1.0V)
Transient Response (VOUT=1.0V) Transient Response (VOUT=1.0V)
20mV/div
VOUT
20mV/div
VOUT
500mA/div
IOUT
500mA/div
IOUT
VIN=5.0V IOUT=0A to 0.5A
50s/div
VIN=5.0V IOUT=0.5A to 1A
50s/div
(c) 2009 Semtech Corp.
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SC189
Pin Descriptions
Pin # (MPLD-UT6)
1
Pin # (SOT23-5)
Not Available
Pin Name
NC
Pin Function
No connection. Enable pin. When connected to logic high or tied to VIN pin, the SC189 is on. When connected to logic low, the device enters shutdown and consumes less than 1A of current. The enable pin has a 1 M internal pulldown resistor. This resistor is switched in circuit whenever the EN pin is below the enable input high threshold, or when the part is in undervoltage lockout. Input power supplies. Powers the internal circuitry and is connected to the source of highside P channel MOSFET. Switching node - connect an inductor between this pin and the output capacitor. Ground connection. Output voltage sense pin. Thermal pad for heatsinking purposes. This pad is not connected internally. Connect it to GND plane.
2
3
EN
3 4 5 6 T
1 5 2 4 Not Available
VIN LX GND VOUT Thermal Pad
(c) 2009 Semtech Corp.
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SC189
Block Diagram
VIN
Current Amp
Internal Oscillator
Ramp Generator
Plimit Comp Plimit Amp
+ -
VOVP
+
OVP
Control Logic
VOUT
Voltage Select
+
Error Amp
+
PWM Comp
500mV Ref
EN
(c) 2009 Semtech Corp.
15
+
LX
GND
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SC189
Applications Information
Detailed Description
The SC189 is a synchronous step-down pulse width modulated (PWM) voltage mode DC-DC regulator operating at 2.5MHz fixed-frequency. The switching frequency is chosen to minimize the size of the external inductor and capacitors while maintaining high efficiency. shown above. For programming the output voltage from other standard voltage, the RFB1, RFB2 and CFF need to be adjusted to meet the equation shown above. Maximum Power Dissiption of SOT23-5 Package The maximum power dissiption for junction temperature of less than 125C on SOT23-5 package is shown in figure 2. The curve is drawn based on the JA of 90C/W which is measured in free convection, mounted on 10mm x 10mm, 2 layer FR4 PCB shown in figure 8 with copper of 1oz for each layer. The maximum power dissiption may limit the maximum output current over temperature. The figure 3 and figure 4 show the typical maximum output current for TJ 125C over temperature of VIN=5.0V and VIN=3.3V, respectively. If using inductor with higher loss (i.e., chip inductor), due to the higher board temperature, the JA will be a little bit higher.
Operation
During normal operation, the internal highside PMOS device is activated on each rising edge of the internal oscillator. The voltage feedback loop uses an internal feedback resistor divider. The period is set by the on board oscillator when in PWM mode at average to high loads. The device has an internal low-side synchronous NMOS device and does not require a Schottky diode on the LX pin. The device operates as a buck converter in PWM mode with a fixed frequency of 2.5MHz.
Output Voltage Selection
The SC189 is designed for fixed output voltage. There are some options for preset output voltage shown in Table 1. If the voltage desired is not shown in the Table 1, it can be programmed via an external resistor divider. There will be typical 1uA current flowing into the VOUT pin. The typical schematic of adjustable output voltage option from the part with standard 1.0V, the SC189A, is shown in Figure 1. The CFF is needed for maintain the performance of the transient response. The proper value of CFF can be calculated by the equation
C FF [nF ] = 10 x
Protection Features
The SC189 provides the following protection features: Thermal Shutdown Current Limit Over-Voltage Protection Soft-Start Operation
* * * *
Thermal Shutdown
The device has a thermal shutdown feature to protect the SC189 if the junction temperature exceeds 160C. During thermal shutdown, the on-chip power devices are disabled with the LX output floating. When the die temperature drops by 10C, the part will initiate a soft start recovery to normal operation.
(VOUT - 0.5)2 VOSTD x( ) RFB1[k] (VOUT - VOSTD ) VOSTD - 0.5
,where the VOSTD is the standard voltage shown in Table 1.
To simplify the design, it is recommended to program the desired output voltage from standard 1.0V (Std VOUT=1.0V) Current Limit Schematic of Adjustable VOUT from SC189A as shown in The internal PMOS power device in the switching stage is Figure 1 with a proper CFF calculated from the equation protected by current limit feature. If the output is loaded L above the PMOS current limit for 32 consecutive cycles, V V LX VIN the SC189 enters foldback current limit mode and the C C R GND output current is limited to the current limit holding C R current (ICL_HOLD) of a few hundred milliampere. Under Enable EN VOUT R these conditions the output voltage will be the product RFB1 = (VOUT - 1) x RFB 2 SC189A of I CL_HOLD and the load resistance. The current limit holding current (ICL_HOLD) will be decreased when output Figure 1 -- Typical schematic for adjustable output voltage is increased. The load presented must fall below voltage option from standard 1.0V of SC189A
IN OUT IN OUT EN FB1 FF
10k
FB2
(2) R (c) 2009 Semtech =10k and C Corp.
FB2
Note: (1) REN is optional.
FF
=10nF for standard design.
16
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SC189
Applications Information (continued)
Maximum Power Dissiption for T J 125 C SOT23-5 Package 1500 1200
900
600
300
the current limit holding current for the SC189 to exit foldback current limit mode. Figure 5 shows the typical current limit holding current decreasing rate over different output voltage. The SC189 is capable of sustaining an indefinite short circuit without damage and will resume normal operation when the fault is removed. The foldback current limit mode will be disabled during the soft-start.
110 125
Power Dissiption (mW)
JA= 90 C/W
0 -40 -25 -10 5 20 35 50 65 80 Ambient Temperature ( C) 95
Over-Voltage Protection
In the event of a 15% over-voltage on the output, the PWM drive is disabled with LX pin floating.
Figure 2 -- Maximum power dissiption of SOT23-5 packageOutput Current for T 125C over temperature Maximum
J
2.0 1.8 1.6 VOUT=1.2V
Soft-Start
The soft-start mode is activated after VIN reaches its UVLO and EN signal is set high to enable the part. An over temperature shutdown event will also activate the soft start sequence. Soft-start mode controls the maximum current during startup thus limiting in-rush current. The PMOS current limit is stepped through four soft start levels of approximately 20%, 25%, 40%, & 100%. Each step is maintained for 20s following internal reference start up of 20s giving the total nominal startup period of 100s. During startup, the chip operates in controlling the inductor current swings between 0A and current limit. If VOUT reaches 90% of the target within the first 2 current levels, the chip continues in hysteretic mode till the end of the soft-start time period before switching to PWM mode. If VOUT does not reach 90% by the end of the second current limit level, soft start will continue to level 3 or level 4 till the output voltage reaches 96% and will then transition into PWM mode. After the full soft start time period, the SC189 will switch into PWM mode operation regardless of the VOUT level. The SC189 is capable of starting up into a pre-biased output. When the output is precharged by another supply rail, the SC189 will not discharge the output during the soft start interval.
Output Current (A)
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -40 -25 -10 5 20 35 50 65 80 Ambient Temperature ( C) 95 110 125 VOUT= 3.3V VOUT=2.5V
VIN= 5.0V JA= 90 C/W
Figure 3 -- Typical maximum output current over temperature of SOT23-5for T 125C VIN= 5.0V package, Maximum Output Current
J
2.0 1.8 1.6 VOUT=1.2V
Output Current (A)
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -40 -25 -10 5 20 35 50 65 80 Ambient Temperature ( C) 95 110 125 VOUT=2.5V
VIN= 3.3V JA= 90 C/W
Figure 4 -- Typical maximum output current over temperature of SOT23-5 package, VIN= 3.3V
Current Limit Holding Current over Vout 150
TA= 25 C
Current Limit holding Current (mA) 120
VIN= 5.0V
90
Shut Down
When the EN pin voltage goes low, the SC189 will run in shutdown mode, drawing less than 1A from the input power supply. The internal switches and bandgap voltage will be immediately turned off.
2.5 3.0 3.5
60
30
VIN= 3.6V
0 1.0 1.5 2.0 Output Voltage (V)
Figure 5 -- Current limit holding current decreasing rate vs. output voltage
(c) 2009 Semtech Corp. 17
Inductor Selection
The SC189 converter has internal loop compensation. The
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SC189
Applications Information (continued)
Vout Code (Vout) Inductor Description 2.2uH, 60m(max) Wire Wound 2.8x3.0x1.5(mm) Vender Part Number Description 10uF,6.3V X5R,0805 A(1.0V),B(1.1V),C(1.2V),E(1.28V),F(1.3V),H(1.5V) Output Capacitor Vender Part Number Qty.
TOKO
1071AS-2R2N
Murata
GRM21BR60J106K
1
1.0uH, 40m(max) Wire Wound 2.8x3.0x1.5(mm)
TOKO
1071AS-1R0N
22uF,6.3V X5R,0805 22uF,6.3V X5R,0805 10uF,6.3V X5R,0805 22uF,6.3V X5R,0805 10uF,4.0V X5R,0603
Murata
GRM21BR60J226M
1
1.0uH, 80m(max) Multilayer Chip 2.5x2.0x1.0(mm)
Murata Murata Murata Murata
GRM21BR60J226M GRM219R60J106K GRM21BR60J226M GRM188R60G106M
1 1 1 2
TOKO
MDT2520-CR1R0M
1.0uH, 69m(max) Multilayer Chip 2.5x2.0x1.0(mm)
Murata
LQM2HPN1R0MG0
Table 2a - Recommended L and output capacitors for Vout=1.0V to 1.5V
Vout Code (Vout) Inductor Description 2.2uH, 60m(max) Wire Wound 2.8x3.0x1.5(mm) Vender
L(1.8V),N(2.0V),T(Y)(2.5V),V(2.7V),Z(3.3V) Output Capacitor Part Number Description 10uF,6.3V X5R,0805 Vender Part Number Qty.
TOKO
1071AS-2R2N
Murata
GRM21BR60J106K
1
1.0uH, 40m(max) Wire Wound 2.8x3.0x1.5(mm) 1.0uH, 80m(max) Multilayer Chip 2.5x2.0x1.0(mm)
TOKO
1071AS-1R0N
22uF,6.3V X5R,0805 22uF,6.3V X5R,0805 10uF,4.0V X5R,0603
Murata
GRM21BR60J226M
1
Murata Murata
GRM21BR60J226M GRM188R60G106M
1 2
TOKO
MDT2520-CR1R0M
Table 2b - Recommended L and output capacitors for Vout=1.8V to 3.3V
(c) 2009 Semtech Corp.
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SC189
Applications Information (continued)
compensation is designed to work with a output filter corner frequency of less than 100kHz over any operating condition, tolerance and bias effect. The corner frequency of output filter can be defined by the equation
fC 1 L COUT
minimum gap possible to limit the distance that magnetic fields can radiate from the inductor. However shielded inductors typically have a higher DCR and are thus less efficient than a similar sized non-shielded inductor. The SC189 is compatible with small shielded chip inductors for low cost, low profile applications. The inductance roll off characteristic of chip inductor is worse resulting in high ripple current and increased output voltage ripple at heavy load operation. SC189 has OCP peak inductor current threshold of 2.0A minimum, to support 1.5A DC load current, the inductor ripple current at 1.5A DC load current needs to be less than 1A. Final inductor selection depends on various design considerations such as efficiency, EMI, size, and cost. Table 2a and 2b list the manufacturers of recommended inductor and output capacitors. Chip inductors provide smaller footprint and height with lower efficiency and increased output voltage ripple. Transient load performance is equivalent to wire wound inductors. Figure 6 shows the typical efficiency curves for different inductors.
Efficiency 100%
2
Values outside this range may lead to instability, malfunction, or out-of-specification performance. When choosing an inductor, it is important to consider the change in inductance with DC bias current. The inductor saturation current is specified as the current at which the inductance drops a specific percentage from the nominal value. This is approximately 30%. Except for short-circuit or other fault conditions, the peak current must always be less than the saturation current specified by the manufacturer. The peak current is the maximum load current plus one half of the inductor ripple current at the maximum input voltage. Load and/or line transients can cause the peak current to exceed his level for short durations. Maintaining the peak current below the inductor saturation specification keeps the inductor ripple current and the output voltage ripple at acceptable levels. Manufacturers often provide graphs of actual inductance and saturation characteristics versus applied inductor current. The saturation characteristics of the inductor can vary significantly with core temperature. Core and ambient temperatures should be considered when examining the core saturation characteristics. When the inductance has been determined, the DC resistance (DCR) must be examined. The efficiency that can be achieved is dependent on the DCR of the inductor. The lower values give higher efficiency. The RMS DC current rating of the inductor is associated with losses in the copper windings and the resulting temperature rise of the inductor. This is usually specified as the current which produces a 40C temperature rise. Most copper windings are rated to accommodate this temperature rise above maximum ambient. Magnetic fields associated with the output inductor can interfere with nearby circuitry. This can be minimized by the use of low noise shielded inductors which use the
(c) 2009 Semtech Corp. 19
L=1071AS-2R2N (50m_typ)
95% 90% Efficiency (%) 85%
L=1071AS-1R0N (33m_typ)
80%
L=MDT2520-CR1R0M (60m_typ)
75% 70% 65% 60% 0.0 0.3 0.6 0.9 Output Current (A) 1.2 1.5
VIN= 5.0V VOUT= 3.3V TA=25 C
L=LQM2HP1R0MG0 (55m_typ)
Figure 6 -- Typical efficiency curves (VIN=5.0V, VOUT=3.3V)
COUT Selection
The internal voltage loop compensation in the SC189 limits the minimum output capacitor value to 10F if using the inductor of 2.2H. This is due to its influence on the the loop crossover frequency, phase margin, and gain margin. Increasing the output capacitor above this minimum value will reduce the crossover frequency and provide greater phase margin. A total output capacintance should not exceed 30uF to avoid any start-up problems. For most typical applications, it is recommended to use output capacitance of 10uF to 22uF. When choosing output
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SC189
Applications Information (continued)
capacitor's capacitance, verify the voltage derating effect from the capacitor vendors data sheet. Capacitors with X7R or X5R ceramic dielectric are recommended for their low ESR and superior temperature and voltage characteristics. Y5V capacitors should not be used as their temperature coefficients make them unsuitable for this application. The output voltage droop due to a load transient is determined by the capacitance of the ceramic output capacitor. The ceramic capacitor supplies the load current initially until the loop responds. Within a few switching cycles the loop will respond and the inductor current will increase to match the required load. The output voltage droop during the period prior to the loop responding can be related to the choice of output capacitor by the relationship.
COUT = 3 I LOAD VDROOP f OSC
The input capacitor RMS ripple current varies with the input and output voltage. The maximum input capacitor RMS current is found from the equation
I CIN ( RMS ) = VOUT VIN VOUT 1 - VIN
The input voltage ripple and RMS current ripple are at maximum when the input voltage is twice the output voltage or 50% duty cycle. The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the PMOS switch. Low ESR/ESL X5R ceramic capacitors are recommended for this function. To minimise stray inductance ,the capacitor should be placed as closely as possible to the VIN and GND pins of the SC189.
Value at 3.3V (F) 4.42 4.88 4.05 4.91 6.57
Manufacturer Part Nunber Murata GRM21BR61A106K Murata GRM21BR71A106K Murata GRM21BR60J106K Murata GRM21BR70J106K Murata GRM21BR60J226M
Value (F)
Type
Rated Voltage (VDC)
Dimensions LxWxH (mm) 2.0x1.25x1.25 (EIA:0805) 2.0x1.25x1.25 (EIA:0805) 2.0x1.25x1.25 (EIA:0805) 2.0x1.25x1.25 (EIA:0805) 2.0x1.25x1.25 (EIA:0805)
The output capacitor RMS current ripple may be calculated from the equation
I COUT ( RMS ) V 1 VOUT ( IN ( MAX ) - VOUT ) = L f OSC VIN 2 3
1010% 1010% 1010% 1010% 2220%
X5R X7R X5R X7R X5R
10 10 6.3 6.3 6.3
Table 3 lists the manufacturers of recommended output capacitor options.
CIN Selection
The SC189 source input current is a DC supply current with a triangular ripple imposed on it. To prevent large input voltage ripple, a low ESR ceramic capacitor is required. A minimum value of 4.7F should be used. It is important to consider the DC voltage coefficient characteristics when determining the actual required value. To estimate the required input capacitor, determine the acceptable input ripple voltage and calculate the minimum value required for CIN from the equation
VOUT 1 - VIN = V - ESR f OSC I OUT VOUT VIN
20
Table 3 - Recommended Capacitors
C IN
(c) 2009 Semtech Corp.
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SC189
Applications Information (continued)
PCB Layout Considerations
The layout diagram in figure 7 and figure 8 shows a recommended PCB for MLPD-UT6 2x2 and SOT23-5 package, respectively. Fundamental layout rules must be followed since the layout is critical for achieving the performance specified in the Electrical Characteristics table. Poor layout can degrade the performance of the DCDC converter and can contribute to EMI problems, ground bounce, and resistive voltage losses. Poor regulation and instability can result. The following guidelines are recommended when developing a PCB layout: 1. The input capacitor, CIN should be placed as close to the VIN and GND pins as possible. This capacitor provides a low impedance loop for the pulsed currents present at the buck converter's input. Use short wide traces to connect as closely to the IC as possible. This will minimize EMI and input voltage ripple by localizing the high frequency current pulses. 2. Keep the LX pin traces as short as possible to minimize pickup of high frequency switching edges to other parts of the circuit. COUT and L should be connected as close as possible between the LX and GND pins, with a direct return to the GND pin from COUT. 3. Route the output voltage feedback/sense path away from inductor and LX node to minimize noise and magnetic interference. 4. Use a ground plane referenced to the SC189 GND pin. Use several vias to connect to the component side ground to further reduce noise and interference on sensitive circuit nodes. 5. If possible, minimize the resistance from the VOUT and GND pins to the load. This will reduce the voltage drop on the ground plane and improve the load regulation. And it will also improve the overall efficiency by reducing the copper losses on the output and ground planes.
VOUT L
COUT
GND
U1
VIN EN
CIN GND GND GND
(a) Top layer for MLPD-UT6 2x2 package
(b) Bottom layer for MLPD 2x2 package Figure 7 -- Recommended PCB Top & Bottom Layer Layout for MLPD-UT6 2x2 Package
L
VOUT
CIN
COUT U1
VIN
GND
(a) Top layer for SOT23-5 package
GND
EN
(b) Bottom layer for SOT23-5 package Figure 8 -- Recommended PCB Top & Bottom Layer Layout for SOT23-5 Package
(c) 2009 Semtech Corp. 21 www.semtech.com
SC189
Outline Drawing - 2x2 MLPD-UT6
DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX
A A1 A2 b D D1 E E1 e L N aaa bbb .024 .002 (.006) .007 .010 .012 .075 .079 .083 .061 .067 .071 .075 .079 .083 .026 .031 .035 .020 BSC .010 .014 .018 6 .003 .004 .018 .000 0.60 0.05 (0.1524) 0.18 0.25 0.30 1.90 2.00 2.10 1.55 1.70 1.80 1.90 2.00 2.10 0.65 0.80 0.90 0.50 BSC 0.25 0.35 0.45 6 0.08 0.10 0.45 0.00
A
D
B
PIN 1 INDICATOR (LASER MARK)
E
A2 A aaa C A1 D1 1 LxN E1 2 C SEATING PLANE
N e
NOTES:
bxN bbb CAB
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.
Land Pattern - 2x2 MLPD-UT6
H R
DIM
(C) K G Z
C G H K P R X Y Z
DIMENSIONS INCHES MILLIMETERS
(.077) .047 .067 .031 .020 .006 .012 .030 .106 (1.95) 1.20 1.70 0.80 0.50 0.15 0.30 0.75 2.70
Y P X
NOTES: 1. 2. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE.
3.
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SC189
Outline Drawing - SOT23-5
Land Pattern - SOT23-5
X
C G P X Y Z
DIMENSIONS
DIM MILLIMETERS (2.50) 1.40 0.95 0.60 1.10 3.60
(C) Y P
NOTES:
G
Z
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. 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 www.semtech.com
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