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LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
DESCRIPTION
KEY FEATURES
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The LX1741 is a compact high efficiency step-up boost controller. Featuring a pseudo-hysteretic pulse frequency modulation topology, the LX1741 was designed for maximum efficiency, reduced board size, and minimal cost. Utilizing an external N-Channel MOSFET, the LX1741 offers designers maximum flexibility with respect to efficiency and cost. The LX1741 provides several design enhancements that improve overall performance under very light load currents by implementing control circuitry that is optimized for portable systems - thus providing a quiescent supply current of only 80A (typ) and a shutdown current of less than 1A. The input voltage ranges from 1.6V to 6.0V, allowing for a wide selection of system battery voltages. Start-up
operation is guaranteed at 1.6V input The output voltage is programmed easily using two external resistors in conjunction with the feedback pin. Depending on the MOSFET selected, the LX1741 is capable of achieving output voltages much higher than 40V. The LX1741 has an additional feature for simple dynamic adjustment of the output voltage (i.e., up to 15% of the nominal output voltage). Voltage adjustment is achieved via an analog reference signal or a direct PWM input signal applied to the ADJ pin. Any PWM amplitude is easily accommodated with a single external resistor. The LX1741 is available in both the 8Pin MSOP, and the miniature 8-Pin MLP requiring minimal PCB area.
> 85% Maximum Efficiency 80A Typical Quiescent Supply Current Externally Programmable Peak Inductor Current Limit For Maximum Efficiency Logic Controlled Shutdown < 0.5 A Shutdown Current (typ) Dynamic Output Voltage Adjustment Via Analog Reference Or Direct PWM Input 8-Pin MSOP Package or 8-Pin MLP APPLICATIONS/BENEFITS Pagers Wireless Phones PDAs Handheld Computers General LCD Bias Applications LED Driver
IMPORTANT: For the most current data, consult MICROSEMI's website: http://www.microsemi.com
PRODUCT HIGHLIGHT
L1
VLCD = 18V 15%
C1 4.7F
VBAT = 1.6V to 6.0V
47H 1206 Case Size
NDRV IN SRC SHDN
ON OFF
LX1741
FB ADJ GND CS RCS 1k
LX1741 LX1741
TA (C) 0 to 70
PACKAGE ORDER INFO Plastic MLP Plastic MSOP LM 8-Pin DU 8-Pin LX1741CLM LX1741CDU
Note: Available in Tape & Reel. Append the letter "T" to the part number. (i.e. LX1741CDUT)
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC)..................................................................................... -0.3V to 7.0V Feedback Input Voltage (VFB).............................................................. -0.3V to VIN + 0.3V Shutdown Input Voltage (V SHDN )........................................................ -0.3V to VIN + 0.3V PWM Input Amplitude......................................................................... -0.3V to VIN + 0.3V Analog Adjust Input Voltage (VADJ) ................................................................ -0.3V to VIN Source Input Current (ISRC) ..................................................................................0.80 ARMS Operating Junction Temperature ................................................................................ 150C Storage Temperature Range ........................................................................ -65C to 150C Lead Temperature (Soldering 180 seconds)............................................................... 235C
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of specified terminal.
PACKAGE PIN OUT
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SRC GND CS ADJ
1 2 3 4
(Top View)
8 7 6 5
NDRV IN FB SHDN
DU PACKAGE
SRC GND
1 2 3 4
(Top View)
8 7 6 5
NDRV IN FB SHDN
THERMAL DATA
CS ADJ
DU
Plastic MSOP 8-Pin JC JA 206C/W 39C/W
LM PACKAGE
THERMAL RESISTANCE-JUNCTION TO AMBIENT, THERMAL RESISTANCE-JUNCTION TO CASE,
LM Plastic MLP 8-Pin
THERMAL RESISTANCE-JUNCTION TO AMBIENT, THERMAL RESISTANCE-JUNCTION TO CASE,
JC
JA
41C/W 5.2C/W
Junction Temperature Calculation: TJ = TA + (PD x JC). The JA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. FUNCTIONAL PIN DESCRIPTION NAME IN FB DESCRIPTION Unregulated IC Supply Voltage Input - Input range from +1.6V to 6.0V. Bypass with a 1F or greater capacitor for operation below 2.0V. Feedback Input - Connect to a resistive divider network between the output and GND to set the voltage at VFB (see Output Voltage Programming: Application Information). Active-Low Shutdown Input - A logic low shuts down the device and reduces the supply current to 0.1A. Connect SHDN to VCC for normal operation. MOSFET Gate Driver - Connects to an external N-Channel MOSFET.
SHDN
NDRV CS GND ADJ SRC
PACKAGE DATA PACKAGE DATA
Current-Sense Amplifier Input - Connecting a resistor between CS and GND sets the peak inductor current limit. Common terminal for ground reference. An applied PWM Signal Input becomes the internal reference, via an internal filter and gain resistor, thus allowing for a dynamic output voltage adjustment of 15% (i.e., corresponding to the duty cycle variance). Connecting this pin to ground causes the device to revert to the internal voltage reference (note: refer to figure 8). MOSFET Current Sense Input - Connects to the External N-Channel MOSFET Source.
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0C TA 70C except where otherwise noted and the following test conditions: VIN = 3V, VOUT = 18.5V, VADJ = 0V, RLOAD = 9.25k, SHDN = VIN LX1741 Parameter Symbol Test Conditions Units Min Typ Max Operating Voltage VIN 1.6 6.0 V Minimum Start-up Voltage VSU 1.6 V TA = +25C
Start-up Voltage Temperature Coefficient Quiescent Current FB Threshold Voltage FB Input Bias Current ADJ Input Voltage Range
1
ELECTRICAL CHARACTERISTICS
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kVST
-2 VFB = 1.5V V SHDN < 0.4V VADJ = GND VFB = 1.4V VADJ = VFB = 1.29V 80 0.2 1.290 100 0.5 1.316 200
VIN - 100mV
mV/C A A V nA V A ARMS nA V V A mA ns mA mA ns
IQ VFB IFB VADJ IADJ ISRC I SHDN V SHDN V SHDN ICS IMIN tD ISNK ISRC tOFF
1.264 -200 0 0.3 -50 1.6 3.0
ADJ Input Bias Current SRC Input Current Shutdown Input Bias Current Shutdown High Input Voltage Shutdown Low Input Voltage Current Sense Bias Current Minimum Peak Current Comparator A Delay NDRV Sink Current NDRV Source Current Minimum Off-Time
SHDN = GND VIN = 2V VIN = 2V
GBNT 2 GBNT VIN = 5V VIN = 5V VFB = 1V
2
1.0 0.8 50 0.4 7.0
5.0 145 620
50 100 100
500
Notes: 1. When using a DC source to adjust VOUT, the recommended VADJ (range) is from 0.9V to 1.50V: see figure 3 and 8. o 2. Guaranteed typical value (not tested) @ TA = 25 C (see section "Inductor Selection and Current Limit Programming")
SIMPLIFIED BLOCK DIAGRAM
FB A NDRV Reference Logic 50pF 2.5M 1.29V Reference B 4 A CS SRC Logic Controller Driver GND
ADJ
ELECTRICALS ELECTRICALS
IN
Shutdown Logic
SHDN
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
APPLICATION CIRCUITS
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Typical LCD Bias Applications
L1 VBAT = (1.6V to 6.0V) 47H
NDRV SRC
C2* 1nF R1
R VOUT = VREF 1 + 1 R2
C1 4.7F
IN SHDN
LX1741
ADJ FB CS GND
RCS 1k
R2
* Optional Component used to reduce output voltage ripple.
Figure 1 - Fixed Output Voltage Operation
L1 VBAT = (1.6V to 6.0V) 47H
NDRV SRC
C2* 1nF R1
R VOUT = VADJ 1 + 1 R 2
C1 4.7F
IN SHDN
RPWM 100kHz VPWM = 3.0V
625k
LX1741
ADJ FB CS GND
RCS 1k
R2
* Optional Component used to reduce output voltage ripple.
APPLICATIONS APPLICATIONS
Figure 2 - Dynamic Output Voltage Operation Via PWM Input Note: An in-series RPWM will attenuate the PWM amplitude to the proper signal level at the ADJ pin. With the RPWM value shown, a PWM signal having a duty of 30% to 50% will generate 0.9V to 1.5V at the ADJ pin.
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
APPLICATION CIRCUITS (CONTINUED)
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Typical LCD Bias Applications (Cont)
L1 VBAT = (1.6V to 6.0V) 47H
NDRV SRC
C2* 1nF R1
R VOUT = VADJ 1 + 1 R2
C1 4.7F
IN SHDN
LX1741
ADJ VADJ = 0.9V to 1.5V + FB CS GND
RCS 1k
R2
* Optional Component used to reduce output voltage ripple.
Figure 3 - Dynamic Output Voltage Operation Via Analog Voltage Input
LED Driver Application
L1
VBAT = 1.6V to 6.0V
47H 1206 Case Size
C1 4.7F
NDRV IN
ON OFF
SRC SHDN
LX1741
FB ADJ CS GND RCS 1k
R1 1
VF = 3.6V typ. ILED = 20mA to 0.25mA
I LED = 1 VADJ - 4VF R 2 ( R 3 R1 + R 2 )
R2 59k
A A PPLICATIONS APPLICATIONS
R3 63.4
Figure 4 - LED Driver with Full-Range Dimming Via PWM Input Note The component values shown are only examples for a working system. Actual values will vary greatly depending on desired parameters, efficiency, and layout constraints.
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
APPLICATION CIRCUITS (CONTINUED)
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L1 47H
D1 B150/B 50V
Vbat = 3.2V
C1 4.7uF 50V C2 1nF 50V
Vout = 40V
R1 1M Q1 3 x BSS138
7 5 2 4
8 1 6 3 Rcs 20K
LX1741
R2 30.9K
Figure 5 - Application of Fixed Output, 40V @ 20mA
C3 1uF 25V
D3 UPS5819 D2 UPS5819 C5 1uF 25V
-VOUT
L1 47H
C1 1uF 25V
D1 UPS5819
VBAT
C4 4.7uF 25V Q1 FDV303N D4 UPS5819 C6 1uF 25V C1 1000pF 50V
+VOUT
R1 787K
7 5 2 4
8 1 6 3 R8 4.02K R2 49.9K
A APPLICATIONS
LX1741
Figure 6 - Application of Dual Output, 20V @ 2mA
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 6
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
APPLICATION INFORMATION
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FUNCTIONAL DESCRIPTION The LX1741 is a Pulse Frequency Modulated (PFM) boost converter that is optimized for large step up voltage applications like LCD biasing. It operates in a pseudohysteretic mode with a fixed switch "off time" of 300ns. Converter switching is enabled when the feedback voltage, VFB, falls below the 1.29V reference or VADJ (see Block Diagram). When this occurs, comparator A activates the off-time controller. The off-time controller and the current limiter circuit activate comparator B which toggles the NDRV output circuit. The NDRV output is switched "on" (and remains "on") until the inductor current ramps up to the peak current level. This current level is set via the external RCS resistor and monitored through the CS and SRC inputs. The load is powered from energy stored in the output capacitor during the inductor charging cycle. Once the peak inductor current value is achieved, the NDRV output is turned off (off-time is typically 300ns) allowing a portion of the energy stored in the inductor to be delivered to the load. This causes the output voltage to continue to rise at the input to the feedback circuit (i.e., comparator A). If the voltage at the FB input is still less than 1.29V at the end of the off-time period, the NDRV output switches the external FET "on" and the inductor charging cycle repeats until VFB is greater than the internal reference. This switching behavior is shown in Figure 9 and 11. The application of an external voltage source at the ADJ pin allows for output voltage adjustment over a typical range of approximately 15%. The designer can select one of two possible methods. One option is to vary the reference voltage directly at the ADJ pin by applying a DC voltage from 0.9 to 1.5V. The second option is to connect a PWM logic signal to the ADJ pin (e.g., see Figure 2). The LX1741 includes an internal 50pF capacitor to ground that works with an external resistor to create a low-pass filter (i.e., filter out the AC component of a pulse width modulated input of fPWM 100KHz). The adjustment voltage level is selectable (with limited accuracy) by implementing the voltage divider created between the external series resistor and the internal 2.5M resistor. If the DC voltage at the ADJ pin drops below 0.6V, the device will revert to the internal reference voltage level of 1.29V. A typical adjustment curve is shown in Figure 8 (see section titled: Characteristic Curves). Disabling the LX1741 is achieved by driving the SHDN pin with a low-level logic signal thus reducing the device power consumption to less than 1A.
Copyright 2000 Rev. 1.1, 2002-11-21
OUTPUT VOLTAGE PROGRAMMING Selecting the appropriate values for R1 and R2 in the voltage divider connected to the feedback pin programs the output voltage. Using a value of 49.9K for R2 works well in most applications. R1 can be determined by the following equation (where VREF = 1.29V nominal):
R1 = R2 x
(VOUT - VREF )
VREF
DESIGN EXAMPLE: Let R2 equals 49.9K and the required VOUT equal to 18V. (18V - 1.29V ) = 646.4K R1 = 49.9K x 1.29V INDUCTOR SELECTION AND CURRENT LIMIT PROGRAMMING Setting the level of peak inductor current to, at least, 1.5x the expected maximum DC input current will minimize the inductor size, the input ripple current, and the output ripple voltage. The designer is encouraged to use inductors that will not saturate at the peak inductor current level. An inductor value of 47H is recommended. Choosing a lower value emphasizes peak current overshoot while choosing a higher value emphasizes output ripple voltage. The peak switch current is defined using a resistor placed between the CS terminal and ground and the IPEAK equation is:
I PEAK = I MIN + V IN

L

t D + I SCALE R CS

The maximum IPEAK value is limited by the ISRC value (max. = 0.8ARMS). The minimum IPEAK value is defined when RCS is zero. A typical value for the minimum peak current (IMIN) at 25oC is 145mA. The parameter tD is related to internal operation of comparator A. A typical value at 25oC is 620ns. A typical value of ISCALE at 25oC is 31mA per K. All of these parameters have an effect on the final IPEAK value. DESIGN EXAMPLE: Determine IPEAK where VIN equals 3.0V and RCS equals 4.02K using nominal values for all other parameters.
IPEAK =145mA+ 3.0V
APPLICATIONS APPLICATIONS
47H
x 620ns+ 31mA x 4.02K k
The result of this example yields a nominal IPEAK equal to 145mA + 39.6mA + 124.6ma = 309.2mA.
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
APPLICATION INFORMATION (CONTINUED)
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OUTPUT RIPPLE CAPACITOR SELECTION Output voltage ripple is a function of the inductor value (L), the output capacitor value (COUT), the peak switch current setting (IPEAK), the load current (IOUT), the input voltage (VIN) and the output voltage (VOUT) for a this boost converter regulation scheme. When the switch is first turned on, the peak-to-peak voltage ripple is a function of the output droop (as the inductor current charges to IPEAK), the feedback transition error (i.e., typically 10mV), and the output overshoot (when the stored energy in the inductor is delivered to the load at the end of the charging cycle). Therefore the total ripple voltage is VRIPPLE = VDROOP + VOVERSHOOT + 10mV The initial droop can be estimated as follows where the 0.5v value in the denominator is an estimate of the voltage drop across the inductor and the FET's RDS_ON:
Therefore, for COUT equals 4.7F: VRIPPLE = 28mV + 9.4mV + 10mV = 47.4mV Increasing the output capacitor value results in the reduction of the output voltage ripple voltage. Low ESR capacitors are recommended to reduce ripple caused by the switching current. Multi-layer ceramic capacitors with X5R or X7R dielectric are a superior choice featuring small size, very low ESR, and a temperature stable dielectric. Low ESR electrolytic capacitors such as solid tantalum or OS-CON types are also acceptable. Moreover, adding a capacitor from the output to the feedback pin (C2) allows the internal feedback circuitry to respond faster which further minimizes output voltage ripple and reduces noise coupling into the high impedance feedback input. DIODE SELECTION A Schottky diode is recommended for most applications (e.g. Microsemi UPS5819). The low forward voltage drop and fast recovery time associated with this device supports the switching demands associated with this circuit topology. The designer is encouraged to consider the diode's average and peak current ratings with respect to the application's output and peak inductor current requirements. Further, the diode's reverse breakdown voltage characteristic must be capable of withstanding a negative voltage transition that is greater than VOUT. TRANSISTOR SELECTION The LX1741 can drive up to 100mA of gate drive current. An N-channel MOSFET with a relatively low threshold voltage, low gate charge and low RDS(ON) is required to optimize overall circuit performance. The LXE1741 Evaluation Board uses a Fairchild FDV303. This NMOS device was chosen because it demonstrates an RDS_ON of 0.33 and a total gate charge Qg of 1.64nC (typ.). PCB LAYOUT The LX1741 produces high slew-rate voltage and current waveforms hence; the designer should take this into consideration when laying out the circuit. Minimizing trace lengths from the IC to the inductor, transistor, diode, input and output capacitors, and feedback connection (i.e., pin 6) are typical considerations. Moreover, the designer should maximize the DC input and output trace widths to accommodate peak current levels associated with this circuit.
VDROOP
L x (I PK x I OUT ) C OUT =
(VIN - 0.5)
The output overshoot can be estimated as follows where the 0.5 value in the denominator is an estimate of the voltage drop across the diode:
1 2x
VOVERSHOOT =
L x (I PK - IOUT )2 COUT (VOUT + 0.5 - VIN )
DESIGN EXAMPLE: Determine the VRIPPLE where IPK equals 200mA, IOUT equals 35mA, L equals 47H, COUT equals 4.7F, VIN equals 3.0V, and VOUT equals 18.0V:
x (200mA x 35mA ) 47H 4.7F = 28mV = (3.0 - 0.5)
1 2x
VDROOP
A APPLICATIONS
VOVERSHOOT =
47H 2 x (200mA - 35mA ) 4.7F = 9.4mV (18.0 + 0.5 - 3.0)
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 8
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD
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OVERVIEW The LXE1741 evaluation board is available from Microsemi for assessing overall circuit performance. The evaluation board, shown in Figure 5, is 3 by 3 inches (i.e., 7.6 X 7.6cm) square and factory calibrated to provide a nominal 18V output from a 1.6V to 6.0V input. Circuit designers can easily modify output voltage and current to suit their particular application by replacing the R1 and RCS values respectively. Moreover, inductor, FET, and diodes are easily swapped out to promote design verification of a circuit that maximizes efficiency and minimizes cost for any particular application. The input and output connections are described in Table 1. ELECTRICAL CONNECTIONS Apply the DC input voltage to VBAT (not VCC) however, the LX1741 IC may be driven from a separate DC source via the VCC input (if desired). Connect the test load to VOUT. Primary output voltage adjustment is accomplished by selecting the appropriate value for R1. Optional fine adjustment of the output voltage is achieved by applying either a DC voltage or a PWM-type signal to the VADJ input. Both low frequency (f < 100KHz) and high frequency (f > 100KHz) PWM signals are accommodated by choosing the appropriate jumper connection. Further, the VADJ circuit can be bypassed by selecting the appropriate jumper position (see Table 2). The LX1741 exhibits a low quiescent current (IQ < 1A: typ) during shutdown mode. The SHDN pin can be used to examine shutdown performance on the evaluation board. This pin is pulled-up to VCC via a 10K resistor. Grounding the SHDN pin shuts down the IC however, the load is still capable of drawing current through the inductor & diode circuit path. Hence, VOUT during shutdown will be approximately VBAT minus the inductor and diode forward voltage drop.
The LX1741 can achieve output voltages in excess of 25V. In certain applications, it is necessary to protect the load from excessive voltage excursions. The evaluation board provides a VLIM jumper position for this purpose. Engaging this jumper position ensures that the output voltage does not exceed 25V. The LXE1741 evaluation board provides an easy and cost effective solution for evaluation on the LX1741. The factory installed component list for the evaluation board is provided in Table 3 and the schematic is shown in Figure 6.
Figure 7 - LX1741 Circuit Evaluation Board
Table 1: Input and Output Pin Assignments
Pin Name
VBAT VCC SHDN VOUT VADJ IN
Allowable Range
0 to 6V 1.6V to 6V 0 to VCC VCC to 25V 0 to VCC
Description
Main power supply for output. (Set external current limit to 0.5A) LX1741 power. May be strapped to VBAT or use a separate supply if VCC jumper is in the SEP position. Do not power output from VCC pin on board.. Pulled up to VCC on board (10K), Ground to inhibit the LX1741. Programmed for 18V output, adjustable up to 25V. Apply a DC input or PWM input to adjust the output voltage.
E B EVAL BOARD
Note: All pins are referenced to ground.
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD (CONTINUED)
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Table 2: Jumper Pin Position Assignments
Jumper / Position
VCC/ VBAT VCC/ SEP REF/ EXT REF/ INT ADJ/ HF ADJ/ LF VLIM/ IN VLIM/ OUT
Function
Use this position when powering VBAT and VCC from the same supply. Do not connect power to the VCC input when using this jumper position. Use this position when using a separate VCC supply (different from VBAT). Use this position when using an external source to adjust the output voltage. Use this position when using the fixed output voltage mode. In this mode the output voltage can be varied by changing the value of R1 as described in the data sheet. Use this position when adjusting the output with an external PWM that has a repetition rate in excess of 100KHz. Use this position when adjusting the output with an external PWM that has a repetition rate less than 100KHz. Or when using a DC adjustment voltage. Use this position when adjusting the output voltage to prevent the output voltage from accidentally exceeding 25V. This position disables the output voltage adjustment clamp. This position may be desired if maximizing efficiency when operating near 25V output level.
Note: Always put jumpers in one of the two possible positions
Table 3: Factory Installed Component List for the LX1741Evaluation Board
Ref
C1 C2 C3 C4,5 CR1 L1 JP1-7 SB1-4 Q1 Q2 R1 R2 R3 R4 R5,R6 R7 R8 U1 VR1
Description
CAPACITOR, COG, 1000pF, 0402, 50V CAPACITOR, X7R, 0.1uF, 0805, 50V CAPACITOR, Y5V, 2.2uF, 0805, 16V CAPACITOR, X5R, 4.7uF, 1210, 25V RECTIFIER, SCHOTTKY, 1A, 40V, POWERMITE INDUCTOR, 47UH, 480mA, SMT 3 TERM HEADER, 0.1 IN CTR JUMPER MOSFET, N-CHAN, 25V, SOT-23 TRANSISTOR, NPN, 40V, SOT-23 RESISTOR, 698K, 1/16W, 0603 RESISTOR, 49.9K, 1/16W, 0603 RESISTOR, 619K, 1/16W, 0603 RESISTOR, 100K, 1/16W, 0603 RESISTOR, 1.00K, 1/16W, 0603 RESISTOR, 10.0K, 1/16W, 0603 RESISTOR, 4.02K, 1/16W, 0603 IC, BOOST CONTROLLER ZENER, 24V,225mW, SOT-23
Supplier
MURATA MURATA AVX TAIYO YUDEN MICROSEMI TOKO 3M 3M FAIRCHILD ON PANASONIC PANASONIC PANASONIC PANASONIC PANASONIC PANASONIC PANASONIC MICROSEMI ON
Part Number
GRM36X7R102M050 GRM40X7R104M050 0805YG225ZAT CETMK325BJ475MN UPS5819 A920CY-470M 929647-09-36-I 929955-06 FDV303N MMBT3904LT1 ERJ3EKF6983 ERJ3EKF4992 ERJ3EKF6193 ERJ3EKF1003
EVAL BOARD EVAL BOARD
ERJ3EKF1001 ERJ3EKF1002 ERJ3EKF4021 LX1741 BZX84C24LT1
Note: The minimum part set for a working power supply consists of: C1, C2, C5, CR1, L1, Q1, R1, R2, R8, U1
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD (CONTINUED)
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L1 47H
CR1 UPS5819
VBAT GND
JB1 VCC X
C4 4.7F 25V Q1 FDV303N C5 4.7F 25V C1 1000pF 50V
VOUT
R1 698K
VCC
R7 10K C2 0.1F 50V LX1741 R2 49.9K
GND
SHDN
JB2 REF
R3 619K
R8 4.02K
JB4 VLIM X
VR1 24V 225mW BZX84C24LT1
VADJ
R4 100K C3 2.2F 16V
ADJ
Q2 MMBT3904LT1
R5 1K
R6 1K
Figure 8 - LX1741 Boost Evaluation Board Schematic
CHARACTERISTIC CURVES
30
25
Channel 1
20 Output Voltage
Channel 2
15
10
5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7
Adj ustment Voltage
Figure 9 - VOUT and Inductor Current Waveforms
Channel 1: VOUT (AC coupled; 100mV/div) Channel 2: Inductor Current (100mA/div.) Configuration: VIN = 1.6V, VOUT = 5.0V, IOUT = 20.0mA
* * *
Figure 10 - Typical VOUT versus VADJ
CHARTS CHARTS
0 ~ 0.6V : LX1741 uses internal 1.29V reference. 0.7V ~ 0.8V : transition from internal to external reference. 0.9 to 1.6V : LX1741 defaults to external voltage reference.
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 11
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
CHARACTERISTIC CURVES
WWW .Microsemi .C OM
Channel 1
100%
90%
Efficiency (%)
Channel 2
80%
70%
60%
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Output Current
Figure 11 - VOUT and Inductor Current Waveforms (mA)
Channel 1: VOUT (AC coupled; 100mV/div) Channel 2: Inductor Current (100mA/div.) Configuration: VIN = 3.0V, VOUT = 17.9V, IOUT = 11.0mA
Figure 12 - Efficiency vs. Output Current (mA)
Configuration: VIN = 3.0V, VOUT = 17.9V, L1 = 47.0H
100%
100%
90%
90%
Efficiency (%)
80%
Efficiency (%)
80%
70%
70%
60%
60%
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Output Current
Output Current
CHARTS CHARTS
Figure 13 - Efficiency vs. Output Current (mA)
Configuration: VIN = 5.2V, VOUT = 17.9V, L1 = 94.0H
Figure 14 - Efficiency vs. Output Current (mA)
Configuration: VIN = 3.0V, VOUT = 10.0V, L1 = 47.0H
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 12
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
CHARACTERISTIC CURVES
WWW .Microsemi .C OM
100%
100%
90%
90%
Efficiency (%)
Efficiency (%)
80%
80%
70%
70%
60%
60%
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Output Current
Output Current
Figure 15 - Efficiency vs. Output Current (mA)
Configuration: VIN = 1.6V, VOUT = 5.0V, L1 = 47.0H
Figure 16 - Efficiency vs. Output Current (mA)
Configuration: VIN = 3.0V, VOUT = 5.0V, L1 = 47.0H
100%
6
90%
5
Gate Drive Voltage (V)
Efficiency (%)
4
80%
3
70%
2
60%
1
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
0 0 20 40 60 80 100 120
Output Current
Drive Current (mA)
Figure 17 - Efficiency vs. Output Current (mA)
Configuration: VIN = 3.0V, VOUT = 5.0V, L1 = 47.0H
Figure 18 - Gate Drive Voltage vs. Drive Current (mA)
CHARTS CHARTS
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 13
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
PACKAGE DIMENSIONS
WWW .Microsemi .C OM
DU
8-Pin Miniature Shrink Outline Package (MSOP)
A
Dim A B C D G H J K L M N P
B
H
G P C N L K M
D
MILLIMETERS MIN MAX 2.85 3.05 2.90 3.10 - 1.10 0.25 0.40 0.65 BSC 0.38 0.64 0.13 0.18 0.95 BSC 0.40 0.70 3 0.05 0.15 4.75 5.05
INCHES MIN MAX .112 .120 .114 .122 - 0.043 0.009 0.160 0.025 BSC 0.015 0.025 0.005 0.007 0.037 BSC 0.016 0.027 3 0.002 0.006 0.187 0.198
LM
8-Pin Plastic MLP-Micro Exposed Pad
Dim
D L2 K E D2 E2 L2
L
e
b
A2 A3
A A1
Internally Connected together, but isolated from all other terminals
A A1 A2 A3 b D E e D2 E2 K L L2
Note:
MILLIMETERS MIN MAX 0.80 1.00 0.00 0.05 0.65 0.75 0.15 0.25 0.28 0.38 2.90 3.10 2.90 3.10 0.65 BSC 1.52 2.08 1.02 1.31 0.20 * 0.20 0.60 0 0.13 0 12
INCHES MIN MAX 0.031 0.039 0.000 0.002 0.025 0.029 0.005 0.009 0.011 0.015 0.114 0.122 0.114 0.122 0.025 BSC 0.060 0.082 0.040 0.052 0.008 * 0.008 0.023 0 0.005 0 12
MECHANICALS MECHANICALS
1. Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006") on any side. Lead dimension shall not include solder coverage. Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 14
LX1741
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
NOTES
WWW .Microsemi .C OM
NOTES NOTES
PRODUCTION DATA - Information contained in this document is proprietary to Microsemi and is current as of publication date. This document may not be modified in any way without the express written consent of Microsemi. Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time.
Copyright 2000 Rev. 1.1, 2002-11-21
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 15

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