SC4505MLTRT Semtech, SC4505MLTRT Datasheet

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SC4505MLTRT

Manufacturer Part Number
SC4505MLTRT
Description
IC,SMPS CONTROLLER,CURRENT-MODE,LLCC,12PIN,PLASTIC
Manufacturer
Semtech
Datasheet

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Part Number:
SC4505MLTRT
Manufacturer:
MEDIATEK
Quantity:
800
The SC4505 is a high-frequency PWM current-mode step-
up switching regulator with an integrated 2A power tran-
sistor. Its high switching frequency (1MHz) allows the use
of tiny surface-mount external passive components. The
internal switch is rated at 36V which makes the con-
verter ideal for multiple LED series operation with opti-
mal current matching. Two programmable independent
current source structure allows dual panel LED backlight
and flash operation.
The operating frequency of the SC4505 is set at 1MHz.
The selected operating frequency gives the SC4505 de-
sign flexibility for size, cost and efficiency optimization.
The SC4505 is available in thermally enhanced 16-pin
MLPQ package (3x3x0.9mm) with embedded over tem-
perature protection.
POWER MANAGEMENT
Revision: December 12, 2007
Typical Application Circuit
Description
VIN: 2.6 V ~ 6.0V
PGND
EN_BL
EN_FL
AGND
FL_TRB
RO1SET
6.9 8k
0
C2
2.2u
0 .33uF
C3
RO2SET
1.5 4k
16
15
14
13
12
11
10
IHLP -2525CZ-01-1R5-M-01
9
VIN
FTO
FL_TRB
EN_FL
EN_BL
IO1SET
IO2SET
AGND
L1
Figure 1. SC4505 Application Circuit for Backlight and Flashlight LED Driver
PGND
PGND
COMP
SC4505
SW
SW
IO2
IO1
VO
1
2
3
4
5
6
7
8
Power
Ground
0
3.0 1k
R1
0
2
LED: SML-LX0603UWD
12n
10BQ015
C6
All Capacitors are Ceramic.
D1
Analog
Ground
1
2.2u F
C1
0
0
L ED
L ED
L ED
D6
(Optional)
D2
D4
12n
C4
1
L ED
Features
Applications
D7
L ED
L ED
D3
D5
0
Two independent current sources for dual LED strands
with optimal current/light matching. Backlight up to
75mA, Flash up to 125mA
Wide input range from 2.6V to 12V
Adaptive output voltage up to 28V with OVP protec-
tion against open circuit conditions
Low shutdown current (<1 A )
Internal Flash/Torch mode with flash timeout to pro-
tect LEDs
1MHz Fixed Frequency Current-Mode Control
Internal 2A current limit for driving large numbers of
LEDs
Supports PWM Dimming from 50Hz to 50kHz
Internal undervoltage lockout
Small, low profile, thermally enhanced 16-MLPQ pack-
age is fully WEEE and RoHS compliant
White LED power supplies
Flat screen LCD bias supplies
TFT bias supplies
Dual panel Handset/Liquid Crystal Display Monitor
Portable media players
Digital video cameras
Digital still cameras
High Efficiency Boost Converter
(Optional)
12n
C5
for Backlight/Flash LED Driver
87
85
83
81
79
77
Boost Converter Efficiency vs Input Voltage
2.5
(2 String of 3 LEDs @30mA)
3
Input Voltage (V)
3.5
4
www.semtech.com
SC4505
4.5
5

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SC4505MLTRT Summary of contents

Page 1

... Digital video cameras Digital still cameras LED: SML-LX0603UWD 10BQ015 2. IO2 7 IO1 12n C6 3.0 1k 12n (Optional) (Optional) 12n Power Analog Ground Ground All Capacitors are Ceramic. 1 SC4505 Boost Converter Efficiency vs Input Voltage (2 String of 3 LEDs @30mA 2.5 3 3.5 4 4.5 Input Voltage (V) www.semtech.com 5 ...

Page 2

... Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device reliability Electrical Characteristics Unless specified 3.6V, -40°C < < 85° 2007 Semtech Corp =6.98K R =1.54K O1SET O2SET ° SC4505 ° ° C ° C ° µ µ www.semtech.com ...

Page 3

... POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified 3.6V, -40°C < < 85° Note 1: Guaranteed by Design 2007 Semtech Corp. =6.98K R =1.54K O1SET O2SET ° ° ° SC4505 µ µ ° ° µ µ www.semtech.com ...

Page 4

... POWER MANAGEMENT Pin Configurations TOP VIEW (16 Pin - MLPQ) Block Diagram Thermal UVLO Shutdown Reference& Internal Regulator EN_BL BL Setpoint IO1SET RO1SET AGND 2007 Semtech Corp. Ordering Information Notes: (1) Only available in tape and reel packaging. A reel contains 3000 devices. (2) Lead free product. This product is fully WEEE and RoHS compliant ...

Page 5

... POWER MANAGEMENT Pin Descriptions Block Diagram Table 1 Note: When EN_FL = 0 FL_TRB = 0 EN_BL = 0 The boost is turned OFF and disabled. 2007 Semtech Corp Table 2 SC4505 www.semtech.com ...

Page 6

... LED are protected from burnout by a user-settable time-out feature. 2007 Semtech Corp. The states of the two LED current regulators are chosen by a three-bit digital input. Either or both of the current regulators can any given time. The converter automatically shuts down to zero-current shutdown mode if all pins are low ...

Page 7

... Table 3. SC4505 Operation States 2007 Semtech Corp. An important note is that continuous operation of mismatched LED strands deteriorates the efficiency of the overall lighting subsystem because the extra voltage must be dropped across that output of the current regulator. Fortunately, for the cases of high mismatch such as the backlight/flashlight example previously mentioned, the time duration in which both heavily mismatched LEDs strands are “ ...

Page 8

... LED current at a fixed value. Overall, this allows usage of small output caps while ensuring precision LED current regulation. 2007 Semtech Corp. Although the mechanics of regulation and frequency dependence may be complex, actual selection of output capacitor can be simplified to two boundary conditions, ...

Page 9

... Figure 2 and Figure 3 below. The relationships between the programming resistor value and the output current setpoint can be described as follows: R 140 V) ( O1SET R ( 154 V) O2SET Where R and R are in Ohms. I O1SET O2SET Amperes. 2007 Semtech Corp. WEBSITE www.kemet.com www.murada.com www.t-yuden.com 160 140 120 100 ...

Page 10

... The FTO pin can simply be grounded to disable this feature, as would be necessary when using I for sub display. O2 2007 Semtech Corp. The relationship between the EN_FL, FL_TRB, FTO pin voltage and the current flowing through the IO2 pin is illustrated in Figure 4 below. EN_FL 0 ...

Page 11

... We can get V OVP 28V The tolerance of the R and R should also be considered determining the OVP triggering point. Usually there is about 5%~8% difference between the calculated value and the measure OVP triggering threshold. 2007 Semtech Corp. VOUT C OUT and will slow down the ...

Page 12

... VIN C4 VIN PGND VIN 2007 Semtech Corp. As shown in Figure 6a, C1 serves as decoupling capacitor for the SC4505. It should be placed close to the VIN and PGND of SC4505 to achieve the best performance the input power filtering capacitor for the boost converter power train the boost converter input inductor ...

Page 13

... The pad at the bottom of the SC4505 should be tied to the analog ground of the SC4505. The analog ground should be kelvin connected to the power ground near the input filtering capacitors for better noise immunity as shown in Figure 6a. 2007 Semtech Corp. and SC4505 ...

Page 14

... Typical Application Circuits Vin=2.6~4. 2 0.33uF C4 R1 100 R3 6.98k R6 R5 1.54k 10k 10k Figure 7a Backlight and Flashlight LED driver for Figure 7b Efficiency Curve for Backlight LEDs Driver Application 2007 Semtech Corp IHLP-252 5CZ-01- 1R5 -M- SC4505 PGND FTO PGND FL_TRB EN_FL ...

Page 15

... POWER MANAGEMENT Outline Drawing - MLPQ - 16 PIN 1 INDICATOR (LASER MARK) aaa C NOTES: Land Pattern - MLPQ - 16 (C) NOTES: Contact Information 2007 Semtech Corp DIM aaa A bbb SEATING PLANE e/2 LxN E bxN D/2 bbb CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. ...

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