SC121ULTRT

Manufacturer Part NumberSC121ULTRT
DescriptionIC BOOST SYNC 1.2A MLPD-6
ManufacturerSemtech
TypeStep-Up (Boost)
SC121ULTRT datasheet
 


Specifications of SC121ULTRT

Internal Switch(s)YesSynchronous RectifierYes
Number Of Outputs1Voltage - Output3.3V, 1.8 ~ 5 V
Current - Output1.2AFrequency - Switching1.2MHz
Voltage - Input0.7 ~ 4.5 VOperating Temperature-40°C ~ 85°C
Mounting TypeSurface MountPackage / Case6-MLPD-UT
Lead Free Status / RoHS StatusLead free / RoHS CompliantPower - Output-
Other namesSC121ULTRTTR  
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POWER MANAGEMENT
Features
Input voltage — 0.7V to 4.5V
Minimum start-up voltage — 0.85V
Output voltage — fi xed at 3.3V; adjustable from 1.8V
to 5.0V
Peak input current limit — 1.2A
Output current at 3.3 V
— 80mA with V
OUT
190mA with V
= 1.5V
IN
Forced PWM operation at all loads
Effi ciency up to 94%
Internal synchronous rectifi er
No forward conduction path during shutdown
Switching frequency — 1.2MHz
Soft-start startup current limiting
Shutdown current — 0.1μA (typ)
Ultra-thin 1.5 × 2.0 × 0.6 (mm) MLPD-UT-6 package
Lead-free and halogen-free
WEEE and RoHS compliant
Applications
MP3 players
Smart phones and cellular phones
Palmtop computers and handheld instruments
PCMCIA cards and memory cards
Digital cordless phones
Personal medical products
Wireless VoIP phones
Small motors
Typical Application Circuit
Single
Cell
(1.2V)
April 13, 2010
Description
The SC121 is a high efficiency, low noise, synchronous
step-up DC-DC converter that provides boosted voltage
levels in low-voltage handheld applications. The wide
input voltage range allows use in systems with single
NiMH or alkaline battery cells as well as in systems with
= 1.0V,
higher voltage battery supplies. It features an internal
IN
1.2A switch and synchronous rectifi er to achieve up to
94% effi ciency and to eliminate the need for an external
Schottky diode. The output voltage can be set to 3.3V
with internal feedback, or to any voltage within the speci-
fi ed range using a standard resistor divider.
The SC121 operates exclusively in Pulse Width Modulation
(PWM) mode for low ripple and fi xed-frequency switching.
Output disconnect capability is included to reduce leakage
current, improve effi ciency, and eliminate external com-
ponents sometimes needed to disconnect the load from
the supply during shutdown.
Low quiescent current is maintained with a high 1.2MHz
operating frequency. Small external components and the
space saving MLPD-UT-6, 1.5×2.0×0.6 (mm) package
make this device an excellent choice for small handheld
applications that require the longest possible battery life.
L1
IN
LX
OUT
EN
FB
GND
C
IN
SC121
© 2010 Semtech Corporation
SC121
Low Voltage Synchronous
Boost Regulator
3.3V
C
OUT
1

SC121ULTRT Summary of contents

  • Page 1

    ... Small external components and the space saving MLPD-UT-6, 1.5×2.0×0.6 (mm) package make this device an excellent choice for small handheld applications that require the longest possible battery life OUT EN FB GND C IN SC121 © 2010 Semtech Corporation SC121 Low Voltage Synchronous Boost Regulator 3.3V C OUT 1 ...

  • Page 2

    ... MLPD-UT; 1.5×2, 6 LEAD θ = 84°C/W JA Marking Information — MLPD-UT 121 yw MLPD-UT; 1.5×2, 6 LEAD yw = date code Ordering Information Device SC121ULTRT SC121EVB OUT 6 Notes: (1) Available in tape and reel only. A reel contains 3,000 devices (2) Lead-free packaging, only. Device is WEEE and RoHS compliant, and halogen-free. EN ...

  • Page 3

    Absolute Maximum Ratings IN, OUT, LX -0.3 to +6 ...

  • Page 4

    Electrical Characteristics (continued) Parameter P-Channel ON Resistance N-Channel ON Resistance N-Channel Current Limit P-Channel Startup Current Limit LX Leakage Current PMOS LX Leakage Current NMOS Logic Input High Logic Input Low Logic Input Current High Logic Input Current Low NOTES: ...

  • Page 5

    Typical Characteristics — V Effi ciency vs. I OUT = 499k Ω Ω 4.7 μ 100 0.1 0.2 ...

  • Page 6

    Typical Characteristics — V Temperature Reg. — Low Load (V = 499k Ω Ω 4.7 μ 1. 0.8V IN 1.78 1.76 ...

  • Page 7

    Typical Characteristics — V Effi ciency vs. I OUT ο FB grounded 4.7 μ 100 2.95V 0.1 0.2 0.5 ...

  • Page 8

    Typical Characteristics — V Temperature Reg. — Low Load (V FB grounded 4.7 μ 1mA OUT 3. 2.95V 3. 2. 1.0V IN 3.26 3.24 3.22 ...

  • Page 9

    Typical Characteristics — V Effi ciency vs. I OUT = 976k Ω 412k Ω 4.7 μ 100 ...

  • Page 10

    Typical Characteristics — V Temperature Reg. — Low Load (V = 976k Ω 412k Ω 4.7 μ 4 3. 1.2V IN 3.95 ...

  • Page 11

    Typical Characteristics — V Effi ciency vs. I OUT = 931k Ω 294k Ω 4.7 μ 100 1. ...

  • Page 12

    Typical Characteristics — V Temperature Reg. — Low Load (V = 931k Ω 294k Ω 4.7 μ 2.2V IN ...

  • Page 13

    Typical Characteristics (continued) PWM Operation V = 3.3V 1.5V 50mA OUT IN OUT V ripple OUT (10mV/div (100mA/div (5V/div) Time = (400ns/div) Startup Max Load Current vs 931k Ω , ...

  • Page 14

    Pin Descriptions MLPD Pin # Pin Name Pin Function 1 LX Switching node — connect an inductor from the input supply to this pin. 2 GND Signal and power ground. Battery or supply input — requires an external 10μF bypass ...

  • Page 15

    Block Diagram IN EN Oscillator and Slope Generator Output Voltage FB Selection Logic V OUT Comp Start-up Oscillator Slope Comp. PWM Comp. + PWM Control - Error Amp REF + - 1.2 V ...

  • Page 16

    Applications Information Detailed Description The SC121 is a synchronous step-up fi xed frequency Pulse Width Modulated (PWM) DC-DC converter utilizing a 1.2MHz fi xed frequency current mode architecture designed to provide output voltages in the range 1.8V to ...

  • Page 17

    Applications Information (continued) PWM Operation The PWM cycle runs xed frequency (f with a variable duty cycle (D). PWM operation continually draws current from the input supply, except for low output loads in which current fl ows ...

  • Page 18

    Applications Information (continued) duty cycle must remain between 20% and 90% for the device to operate within specifi cation. Note that startup with a regulated active load is not the same as startup with a resistive load. The resistive load ...

  • Page 19

    Applications Information (continued) Note that this is a negative quantity, since V 0 < D < 1. For a constant load in steady-state, the inductor current must satisfy ΔI + Δ Substituting the two L-on L-off expressions and ...

  • Page 20

    Applications Information (continued) PCB Layout Considerations Poor layout can degrade the performance of the DC-DC converter and can contribute to EMI problems, ground bounce, and resistive voltage losses. Poor regulation and instability can result. The following simple design rules can ...

  • Page 21

    Outline Drawing — MLPD-UT-6 1.5x2 A PIN 1 INDICATOR (LASER MARK) A aaa LxN N NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS. B ...

  • Page 22

    Land Pattern — MLPD-UT-6 1.5x2 NOTES: 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 ...

  • Page 23

    ... IN SUCH APPLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE CUSTOMER’S OWN RISK. Should a customer purchase or use Semtech products for any such unauthorized application, the customer shall indemnify and hold Semtech and its offi cers, employees, subsidiaries, affi liates, and distributors harmless against all claims, costs damages and attorney fees which could arise. ...