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LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
DESCRIPTION
KEY FEATURES
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The LX1742 is a compact high efficiency step-up boost controller. Featuring a pseudo-hysteretic pulse frequency modulation topology, the LX1742 was designed for maximum efficiency, reduced board size, and minimal cost. Utilizing an internal N-Channel MOSFET, the LX1742 offers designers maximum flexibility with respect to efficiency and cost. The LX1742 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 LX1742 is capable of achieving output voltages as high as 25V and the output voltage is easily programmed using two external resistors in conjunction with the feedback pin. The LX1742 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.
80% Typical Efficiency 80A Typical Quiescent Supply Current Externally Programmable Peak Inductor Current Limit For Maximum Efficiency Logic Controlled Shutdown < 1.0 A Shutdown Current (typ) Dynamic Output Voltage Adjustment Via Analog Reference Or Direct PWM Input 8-Pin MSOP Package 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
VBAT = (1.6V to 6.0V)
L1 47H UPS530
SW IN SHDN OUT C2 * 1nF R1 1M
(For Contrast Adjustment)
VOUT = 18V 15%
LX1742
ADJ FB CS GND
C1 4.7F
RCS 1k
R2 72k
RPWM 625k
100kHz VPWM = 3.0V
PACKAGE ORDER INFO Plastic MSOP DU 8-Pin TA (C) 0 to 70 LX1742CDU
LX1742 LX1742
RoHS Compliant / Pb-free Transition DC: 0432
Note: Available in Tape & Reel. Append the letters "TR" to the part number. (i.e. LX1742CDU-TR)
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
ABSOLUTE MAXIMUM RATINGS Supply Voltage (VIN) ..................................................................................... -0.3V to 7.0V Output Voltage (OUT) ................................................................................................25.0V 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)................................................................................. 500mARMS Operating Junction Temperature................................................................................ 150C Storage Temperature Range.........................................................................-65C to 150C Peak Package Solder Reflow Temp. (40 second max. exposure).................. 260C (+0, -5)
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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SW IN FB SHDN
1 2 3 4 DU PACKAGE
(Top View)
8 7 6 5
OUT GND CS ADJ
RoHS / Pb-free 100% Matte Tin Lead Finish
THERMAL DATA
DU
Plastic MSOP 8-Pin 206C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, JA
THERMAL RESISTANCE-JUNCTION TO CASE, JC 39C/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. Feedback Input - Connect to a resistive divider network between the output and GND to set the output voltage between VCC (IN) and 25V. The feedback threshold is 1.20V. Active-Low Shutdown Input - A logic low shuts down the device and reduces the supply current to 0.1A. When shutdown, the LX1742 isolates the output from the input by turning off the internal MOSFET between LX and OUT. Connect SHDN to VCC for normal operation. Inductor Switching Connection - Internally connected to the drain of a 28V N-channel MOSFET. LX is high impedance in shutdown. Current-Sense Amplifier Input - Connecting a resistor between CS and GND sets the peak inductor current limit. Common terminal for ground reference.
SHDN
SW CS GND ADJ OUT
PACKAGE DATA PACKAGE DATA
PWM Signal Input - Connects to the internal reference, via an internal filter and gain resistor, allowing a dynamic output voltage adjustment 15% in corresponding to a varying duty cycle. 50% duty cycle yields a nominal output set via the FB pin (See Note) or ADJ input voltage range from 0.9V to 1.5V DC Output voltage is adjustable up to 25V (maximum).
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
ELECTRICAL CHARACTERISTICS
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 = 3.0V, VADJ = 0V, SHDN = VIN, VFB = 1.0V, Pin 8 = (not connected), Pin 1 = (+5V through 39.2).
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Parameter
Operating Voltage Minimum Start-up Voltage Start-up Voltage Temperature Coefficient Quiescent Current FB Threshold Voltage FB Input Bias Current ADJ Input Voltage Range
1
Symbol VIN VSU
kVST
Test Conditions
Min 1.6
LX1742 Typ
Max 6.0 1.6
Units V V mV/C A A V nA V nA nA V V A A ns V A
TA = +25C
Guaranteed: not tested Not Switching
-2 80 0.5 1.200 100 1.0 1.225 200
VIN - 100mV
IQ VFB IFB VADJ IADJ I SHDN V SHDN V SHDN ICS RDS(ON) ILEAK tOFF VF IR
V SHDN < 0.4V VADJ = GND
Switching mode
1.175 0 0 0 -50 1.6 2.0
ADJ Input Bias Current Shutdown Input Bias Current Shutdown High Input Voltage Shutdown Low Input Voltage Current Sense Bias Current Internal NFET On-resistance Switch Pin Leakage Current Switch Off-Time Diode Forward Voltage Diode Reverse Current Notes: 1. 2.
VADJ = VFB = 1.20V SHDN = GND VIN = 2V VIN = 2V TA = +25C; ISW = 10mA; VFB = 1V VSW = 25V VFB = 1V TA = +25C; IF = 150mA TA = +25C; VR = 25V
200 50 0.4 6.0
4.0 1.1 0.23 300 1.0 1.5
When using a DC source to adjust VOUT, the recommended VADJ (range) is 0.9V to 1.50V: see figure 9. Guaranteed typical value (not tested) @ TA=25C (see section "Inductor Selection & Current Limit Programming").
SIMPLIFIED BLOCK DIAGRAM
FB A
O ff-time Controller
SW OUT B Driver GND
ADJ
Reference Logic
E ELECTRICALS
1.2V Reference
Current Limiter
4 A CS
IN
Shutdown Logic
SHDN
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
LX1742
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
SW OUT CR1 UPS5819
R VOUT = VREF 1 + 1 R 2
C 2* 1nF
IN SHDN
LX1742 LX1742
ADJ FB CS GND
R1
C1 10F
RCS 4k
R2
* Optional Component used to reduce output voltage ripple.
Figure 1 - Circuit Showing Fixed Output Voltage Operation Using an External Schottky Diode Switch (CR1).
L1 VBAT = (1.6V to 6.0V) 47H
SW IN SHDN OUT
CR1 UPS5819
R VOUT = VADJ 1 + 1 R 2
R1 C 2* 1nF C1 10F RCS 4k R2
* Optional Component used to reduce output voltage ripple.
LX1742 LX1742 RPWM 100kHz VPWM = 3.0V
ADJ 625k GND
FB
CS
Figure 2 - Circuit Showing Dynamic Output Voltage Operation Via PWM Input Using an External Schottky Diode Switch (CR1).
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.
APPLICATIONS APPLICATIONS
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1742
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
SW IN SHDN OUT
LX1742 LX1742
ADJ VADJ = 0.9V to 1.5V + GND
R1
C2* 1nF
R VOUT = VADJ 1+ 1 R 2
FB
CS
C1 10F RCS 4k R2
* Optional Component used to reduce output voltage ripple.
Figure 3 - Circuit Showing Dynamic Output Voltage Operation Via Analog Voltage Input and Using the Internal Diode Switch (Optional).
APPLICATIONS APPLICATIONS
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
APPLICATION INFORMATION
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FUNCTIONAL DESCRIPTION The LX1742 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 1.20V reference or VADJ (see Block Diagram). When this occurs, comparator A activates the off-time controller. The off-time controller and the current limiting circuits activate comparator B and toggles the output driver circuit. The 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 driver 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 1.20V at the end of the off-time period, the output switches the internal FET "on" and the inductor charging cycle repeats until VFB is greater than the internal reference. Typical converter switching behavior is shown in Figure 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 LX1742 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 1.20V. A typical adjustment curve is shown in Figure 9 (see section titled: Characteristic Curves). Disabling the LX1742 is achieved by driving the SHDN pin with a low-level logic signal thus reducing the device power consumption to less than 1A.
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 between 40K and 75K 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 72K and the required VOUT equal to 18V.
R1 = 72K x
(18V - 1.20V ) = 1.M
1.20V
INDUCTOR SELECTION AND CURRENT LIMIT PROGRAMMING Setting the level of peak inductor current to approximately 2X 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 104mA. The parameter tD is related to internal operation of the device. A typical value at 25oC is 800ns. A typical value of ISCALE at 25oC is 22mA 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.
APPLICATIONS APPLICATIONS
IPEAK =104mA+ 3.0V

47H

x800ns+ 22mA x4.02K k
The result of this example yields a nominal IPEAK equal to 243.5mA.
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1742
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 1.2 value in the denominator is an estimate of the typical voltage drop across the inductor and the internal FET's RDS_ON:
VDROOP L x (IPK x IOUT ) C = OUT (VIN - 1.2)
Therefore, for COUT equals 4.7F: VRIPPLE = 38mV + 9.4mV + 10mV = 57.4mV 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 type of 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. The LX1742 has a built in diode that may be used instead of an external device. Using this internal diode reduces system cost however, overall efficiency decreases. The electrical connections corresponding to use of the internal diode are shown in Figure 3. In this configuration, the inductor is connected between the input source and the SW pin (1). The output is taken directly from OUT pin (8).
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:
47 H x (200mA x 35mA ) 4.7 F = 38mV = (3.0 - 1.2)
1 2x
VDROOP
VOVERSHOOT =
47H 2 x (200 mA - 35mA ) 4.7F = 9.4mV (18.0 + 0.5 - 3.0)
PCB LAYOUT The LX1742 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, diode, input and output capacitors, and feedback connection (i.e., pin 3) are typical considerations. Moreover, the designer should maximize the DC input and output trace widths to accommodate peak current levels associated with this circuit.
APPLICATIONS APPLICATIONS
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 7
LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD
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OVERVIEW The LXE1742 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 the output voltage and peak current to suit their particular application by adjusting the R2, R3, and R4 values accordingly. Further, other components are easily swapped out to promote design verification of any particular circuit application. Table 1 describes the evaluation board's electrical interface. ELECTRICAL CONNECTIONS The system level DC input voltage is applied to VIN. Connect the test load to VOUT. The Vin & GND terminal at J4 provides easy test point access. A similar connection is available for monitoring the output voltage via J5. The output voltage is adjusted by selecting appropriate values for R3 and R24. Further adjustment of the output voltage is achieved by applying either a DC voltage or a PWM-type signal to the ADJ input (J4). Application Range
0 to 6V 0 to 6V 0 to VIN 0 to VIN100mV 0V 0V 0 to VIN 0V VIN to 25V N/A 0 to VIN
The evaluation board accommodates both low frequency (f < 100KHz) and high frequency (f > 100KHz) PWM signals by connecting either JU1 or JU4 jumper position respectively. The ADJ pin is easily grounded for fixed voltage applications by inserting a jumper into the JU5 position. Table 2 provides a complete list of all jumper positions. Removing the jumper from the /SHDN position disables the LX1742 by disconnecting pin 4 from VIN. The load is still capable of drawing current through the inductor & diode circuit path when the IC is in shutdown mode. Hence, VOUT during shutdown will be approximately VIN minus the inductor and diode forward voltage drop. The LX1742 can achieve output voltages up to 25V. In certain applications, it is necessary to protect the load from excessive voltage excursions. The evaluation board provides a zener clamp diode (D1) for this purpose. The LXE1742 evaluation board offers a cost effective solution for evaluation of the LX1742. Table 3 provides the factory installed component list for the evaluation board and the board schematic is shown in Figure 4.
Table 1: Input and Output Pin Assignments Name
VIN Vin (J4)
SHDN (J4)
Description
Main power supply input for evaluation board Connected to VIN (Alternate position or test point) Pulled up to VCC on board (10K), Ground to inhibit the LX1742. Apply a DC input or PWM input to adjust the output voltage (note: see figure 9). Circuit ground Additional circuit ground connection point. Apply a DC input or PWM input to adjust the output voltage. Additional circuit ground connection point. Output voltage test point. Programmed for 18V output, adjustable up to 25V.
ADJ (J4) GND (J4) GND FDBK GND2 VOUT SWITCH /SHDN
EVALUATION BOARD EVALUATION BOARD
Test point for LX1742 pin 1. A DC voltage above (below) 1.6V (0.4V) enables (disables) the LX172
Note: All pins are referenced to ground.
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1742
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 VIN VOUT SWITCH FDBK GND / GND2 /SHDN JU3 JU1 JU4 JU5 n/a n/a n/a n/a n/a 1/0 1 1/0/0 0/1/0 0/0/1
Function
Attach the primary input power form to this contact. Input power may also be applied to the pin marked Vin on J4. Use this contact to measure the circuit's output voltage at pin 8. Use this contact to observe the switching waveform at the Schottky anode (i.e., LX1742 pin 1). Use this contact to measure the circuit's feedback voltage at pin 3. Use these contact to connect to circuit ground. Inserting a jumper (1) enables the LX1742 by connecting pin 4 directly to VIN. Removing this jumper (0) disables the LX1742 Remove the factory installed jumper and insert a 4 ~6cm wire loop (optional) to observe the inductor current waveform using a current probe. 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 with an external PWM that has a repetition rate in excess of 100KHz. Use this position to ground the ADJ (pin 5) when using the LX1742 in a fixed output voltage mode
Note: (1) = jumper installed; (0) = jumper not installed.
Table 3: Factory Installed Component List for the LX1742 Evaluation Board
Ref
C1 C2 C3 C4 C5 & C6 CR1 L1 Q1 D1 R1 R2, R5, R6 R3 R4 R7 U1 Notes 1. 2.
Part Description
CAPACITOR, 4.7F, 1210, 35V CAPACITOR, 4.7F, 1210, 35V CAPACITOR, 1000pF, 0805, 35V CAPACITOR, 2.2F, 0603, 35V CAPACITOR, (SPARE); see note 1. Microsemi UPS5819, SCHOTTKY, 1A, 40V, POWERMITE INDUCTOR, 47H, 480mA, SMT MMBT3904 TRANSISTOR, NPN, 40V, SOT-23 BZX84C24, ZENER DIODE, TBD RESISTOR, 625K, 1/16W, 0805 RESISTOR, 1.0K, 1/16W, 0805 RESISTOR, 1.0M, 1/16W, 0805
EVALUATION BOARD EVALUATION BOARD
RESISTOR, 72K, 1/16W, 0805 RESISTOR, 100K, 1/16W, 0805 Microsemi LX1742CDU BOOST CONTROLLER; see note 2. Use these locations to insert additional input (C6) and/or output (C5) capacitance. The minimum part set for a working power supply consists of: C1, C2, CR1, L1, R2, R3, R4, U1.
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD (CONTINUED)
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TP1 Testpoint
J5
CR1 UPS5819 1 2 J4 3 4 Vin /SHDN 2 1 C1 4.7F 35V J2 Jumper + L1 47.0H 1 2 J3 Jumper U1 SW IN /SHDN ADJ 1 2 ADJ J1 R1 Jumper 625K 1 2 J4 Jumper J5 Jumper 2 1 OUT FB CS GND R2 1K D4 BZX84C24/SOT R5 1K R6 1K R4 72K C3 1000pF R3 1M + C2 4.7F 35V
TP2
Testpoint TP3
Testpoint
LX1742CDU Q1 MMBT3904/SOT
R6 100K C4 2.2F 35V GND
TP4
Testpoint
Figure 4 - LXE1742 Boost Evaluation Board Schematic
Note: Factory installed jumper positions shown
EVALUATION BOARD EVALUATION BOARD
Figure 5 - LXE1742 - LX1742 Circuit Evaluation Board
Figure 6 - LXE1742 - Evaluation Board Trace Layout
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD (CONTINUED)
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X4
X3
VIN
L1
Vin /SHDN ADJ
SWITCH
VOUT
CR1 GND U1 JU1 JU4 R1 GND R7 JU5
R2
FDBK
Q1
GND2
Microsemi LX1742
X1
EVALUATION BOARD SGE#3503 REV X2
X2
Figure 7 - LXE1742 - Bottom Trace Layer
Figure 8 - LXE1742 - Board Layout
EVALUATION BOARD EVALUATION BOARD
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
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LX1742
INTEGRATED PRODUCTS
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
CHARACTERISTIC CURVES
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30
100%
25
90%
Output Voltage
20 15 10
Efficiency (%)
80%
70%
5
60%
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
50% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Output Current
0 ~ 0.4V : LX1742 uses internal 1.2V reference. 0.5V ~ 0.7V : transition from internal to external reference. 0.8 to 1.5V : LX1742 defaults to external voltage reference.
Figure 9 - Typical VOUT versus VADJ
Figure 10 - Efficiency vs. Output Current (mA)
Top: VIN = 3.6V, VOUT = 5.2V, L1 = 47.0H Bottom: VIN = 5.5V, VOUT = 18.0V, L1 = 47.0H
1.40
RDS_on (Ohms)
1.30
1.20
1.10
1.00 0 25 50 o 75
Temperature
C
Figure 11 - Typical switching waveforms:
Ch1 - Switch voltage; Ch2 - Output voltage; Ch4 - Inductor current. (VIN = 3.6V, VOUT = 18V, RLOAD = 2K)
Figure 12 - Typical RDS(on) vs. Temperature
Condition: VIN = 3.0V; ISW = 10mA
CHARTS CHARTS
Copyright (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 12
LX1742
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
NOTES
MECHANICALS MECHANICALS
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 (c) 2000 Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 13

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