Not Recommended For New Design LX1431 PROGRAMMABLE REFERENCE T H E I N F I N I T E P O W E R O F I P N N O V A T I O N R O D U C T I O N D H E E T KEY FEATURES Guaranteed 0.4% Initial Voltage Tolerance 0.1Ω Typical Dynamic Output Impedance Fast Turn-on Sink Current Capability, 1mA to 100mA Low Reference Pin Current APPLICATIONS bs ol et e DESCRIPTION In addition, the nominal internal current limit of The LX1431 is an adjustable shunt voltage regulator featuring 100mA sink capability, a 100mA may be decreased with the addition of a single external resistor. 0.4% initial reference voltage tolerance and a For applications requiring an adjustable 0.3% typical temperature stability. This product, which is ideal for use in Pentium® applications, reference, the Linfinity LX6431CLP, a simplified three-pin programmable reference, is equipped with on-chip divider resistors, may be used. Because the LX6431 is pin-forenabling it to be configured as a 5V shunt regulator. In this configuration, the LX1431 has pin compatible with Linfinity's earlier TL431, use of this product provides designers a simple an initial voltage tolerance of only 1% and migration path to the more robust LX6431. A requires no additional external components. The Linfinity LX1431EB evaluation board separate LX6431 data sheet is available which details the specifics of this product. and design kit is available to assist engineers in In addition, Pentium designers may use quickly configuring the most efficient, costeffective Pentium designs. Linfinity's LX8585/8585A 4.6A or LX8584/ The output voltage of the LX1431 may be set 8584A 7A Low Dropout Regulators to achieve the most optimum motherboard configuration. to any value between 2.5V and 36V through the addition of two external resistors, which is of particular importance in the design of both adjustable and switching power supplies. S A T A Linear Regulators Adjustable Power Supplies Switching Power Supplies LX1432EB Evaluation Board For Pentium Applications Available IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com PRODUCT HIGHLIGHT THE LX8584A & LX431 IN 75 & 166MHZ P54C PROCESSOR APPLICATIONS USING 3.3V CACHE 3 5V VO 7A PLACE IN (See Table Below) 2 VIN VOUT 3x 330 F, 6.3V Low ESR Oscon Type from Sanyo LX8584A 1kW ADJ 0.01 F 1kW 1 100 F x 6 10V AVX TYPE TPS 250pF 1 2 3 220 F 10V Low ESR from Sanyo O VO JP1 Short 3.38 Open V+ REF SGND 5 8 2.84k W 0.1% LX1431 0.1 F 50V 3.50 1k 0.1% COL FGND 1 F x 10 SMD JP1 TYPICAL APPLICATION 75/90/100/133MHz, STND, 3.3V Cache 0 to 70 -40 to 85 21k 1% P Load 6 120/166MHz, VRE, 3.3V Cache TA (°C) P SOCKET CAVITY M Thick traces represent high current traces which must be low resistance / low inductance traces in order to achieve good transient response. PACKAGE ORDER INFO Plastic DIP Plastic SOIC DM 8-Pin 8-Pin RoHS Compliant / Pb-free Transition DC: 0503 RoHS Compliant / Pb-free Transition DC: 0440 LX1431CM LX1431IM LX1431CDM LX1431IDM Note: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1431CDM-TR). Copyright © 1997 Rev. 1.2a,2005-03-08 LINFINITY MICROELECTRONICS INC. 11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: 714-893-2570 1 PRODUCT DATABOOK 1996/1997 LX1431 PROGRAMMABLE REFERENCE P R O D U C T I O N A B S O L U T E M A X I M U M R AT I N G S D A T A S H E E T PACKAGE PIN OUTS (Note 1) V+, VCOLLECTOR ................................................................................................................. 36V VCOMP, RTOP, RMID, V REF ...................................................................................................... 6V GND-F to GND-S ........................................................................................................ 0.7V Operating Junction Temperature Plastic (M, DM Packages) ..................................................................................... 150°C Storage Temperature Range ...................................................................... -65°C to 150°C Lead Temperature ..................................................................................................... 300°C COLLECTOR COMP V+ RTOP 1 8 2 7 3 6 4 5 M PACKAGE (Top View) Pb-free / RoHS Peak Package Solder Reflow Temp. (40 second max. exposure)............... 260°C (+0, -5) bs ol et e Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. COLLECTOR COMP V+ RTOP T H E R MAL DATA M PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, θ JA REF RMID GND-F GND-S 1 8 2 7 3 6 4 5 REF RMID GND-F GND-S 95°C/W DM PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, θ JA 165°C/W DM PACKAGE (Top View) RoHS / Pb-free 100% Matte Tin Lead Finish Junction Temperature Calculation: TJ = TA + (PD x θJA). The θ JA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. B LO C K DIAG R A M RTOP V+ 4 3 COMP 2 COLLECTOR 1 5K REF 8 7 O RMID gm= 60µA/V 5K 2.5V 5 GND-SENSE 2 6 GND-FORCE Copyright © 1997 Rev. 1.2a 8/04 PRODUCT DATABOOK 1996/1997 LX1431 PROGRAMMABLE R EFERENCE P R O D U C T I O N D A T A S H E E T ELECTRICAL CHARACTERISTICS (Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX1431C with 0°C ≤ TA ≤ 70°C, LX1431I with -40°C ≤ TA ≤ 85°C.) Parameter Reference Voltage Test Conditions LX1431I LX1431C Units Min. Typ. Max. Min. Typ. Max. VKA = 5V, IK = 2mA, TA = 25°C 2490 2500 VKA = 5V, IK = 2mA 2465 ∆VREF/∆T VKA = 5V, IK = 2mA 50 0.2 ∆V REF IK = 2mA, VKA = 3V to 36V ∆VKA 0.2 VKA = 5V, TA = 25°C [IREF] VKA = 5V 0.6 VKA = VREF to 36V, TA = 25°C IMIN VKA = 36V, VREF = 0V, TA = 25°C [IOFF] VKA = 36V, VREF = 0V VCOLL = 36V, V+ = 5V, VREF = 2.4V, TA = 25°C [ILEAK] V + COLL = 36V, V = 5V, VREF = 2.4V VKA = VREF, IK = 1mA to 100mA, f ≤ 1kHz, TA = 25°C [ZKA ] 80 VKA = VREF + 50mV ILIM 4950 5000 Internal Divider Used, IK = 2mA, TA = +25°C VREF 2510 2490 2500 2510 mV 2535 2480 2520 mV 30 ppm/°C 1.0 0.2 1.0 mV/V bs ol et e Reference Drift Voltage Ratio, Reference to Cathode (Open Loop Gain) Reference Input Current Symbol Minimum Operating Current Off-State Cathode Current Off-State Collector Leakage Current µA µA mA µA µA µA µA Ω mA mV O Dynamic Impedance Collector Current Limit 5V Reference Output 1 0.2 1 1.5 1.2 1 0.6 1 1 1 15 2 1 1 5 2 0.1 0.1 360 100 360 5050 4950 5000 5050 Copyright © 1997 Rev. 1.2a 8/04 3 PRODUCT DATABOOK 1996/1997 LX1431 PROGRAMMABLE REFERENCE P R O D U C T I O N D A T A S H E E T A P P L I C AT I O N I N F O R M AT I O N PIN FUNCTIONS Pin 1 COLL: Open collector of the output transistor. The maximum pin voltage is 36V. The saturation voltage at 100mA is approximately 1V. bs ol et e Pin 2 COMP: Base of the driver for the output transistor. This pin allows additional compensation for complex feedback systems and shutdown of the regulator. It must be left open if unused. COMP, RTOP, RMID, and REF have static discharge protection circuits that must not be activated on a continuous basis. Therefore, the absolute maximum DC voltage on these pins is 6V, well beyond the normal operating conditions. As with all bipolar ICs, the LX1431 contains parasitic diodes which must not be forward biased or else anomalous behavior will result. Pin conditions to be avoided are RTOP below RMID in voltage and any pin below GND-F in voltage (except for GND-S). Pin 3 V+: Bias voltage for the entire shunt regulator. The maximum input voltage is 36V and the minimum to operate is equal to VREF (2.5V). The quiescent current is typically 0.6mA. Pin 4 RTOP: Top of the on-chip 5k-5k resistive divider that guarantees 1% accuracy of operation as a 5V shunt regulator with no external trim. The pin is tied to COLL for selfcontained 5V operation. It may be left open if unused. Pin 5 GND-S: Ground reference for the on-chip resistive divider and shunt regulator circuitry except for the output transistor. This pin allows external current limit of the output transistor with one resistor between GND-F (force) and GND-S (sense). Pin 6 GND-F: Emitter of the output transistor and substrate connection for the die. FREQUENCY COMPENSATION Excess capacitance on the REF pin can introduce enough phase shift to induce oscillation when configured as a reference >2.5V. This can be compensated with capacitance between COLL and REF (phase lead). More complicated feedback loops may require shaping of the frequency response of the LX1431 with dominant pole or pole-zero compensation. This can be accomplished with a capacitor or series resistor and capacitor between COLL and COMP. The compensation schemes mentioned above use voltage feedback to stabilize the circuits. There must be voltage gain at the COLL pin for them to be effective, so the COLL pin must see a reasonable AC impedance. Capacitive loading of the COLL pin reduces the AC impedance, voltage gain, and frequency response, thereby decreasing the effectiveness of the compensation schemes, but also decreasing their necessity. Pin 7 RMID: Middle of the on-chip resistive divider string between RTOP and GND-S. The pin is tied to REF for selfcontained 5V operation. It may be left open if unused. O Pin 8 REF: Control pin of the shunt regulator with a 2.5V threshold. 4 Copyright © 1997 Rev. 1.2a 8/04 PRODUCT DATABOOK 1996/1997 LX1431 PROGRAMMABLE R EFERENCE P R O D U C T I O N D A T A S H E E T GRAPH / CURVE INDEX Characteristic Curves FIGURE # COLLECTOR VSAT vs. TEMPERATURE vs. CURRENT 2. COMPENSATION PIN VOLTAGE vs. TEMPERATURE vs. ICOLL 3. ILIMIT vs. TEMPERATURE WITH EXTERNAL RESISTOR 4. REFERENCE VOLTAGE and REFERENCE CURRENT vs. V+ 5. REFERENCE VOLTAGE and REFERENCE CURRENT vs. V+ 6. 2.5V REFERENCE IK vs. VKA 7. REFERENCE VOLTAGE and REFERENCE CURRENT vs. TEMPERATURE O bs ol et e 1. Copyright © 1997 Rev. 1.2a 8/04 5 PRODUCT DATABOOK 1996/1997 LX1431 PROGRAMMABLE REFERENCE P R O D U C T I O N D S A T A H E E T CHARACTERISTIC CURVES FIGURE 1. — COLLECTOR VSAT vs. TEMPERATURE vs. CURRENT FIGURE 2. — COMPENSATION PIN VOLTAGE vs. TEMPERATURE vs. ICOLL 0.5 (VCOMP) Compensation Pin Voltage - (V) 3 ICOLL = 100mA 2.5 bs ol et e (VSAT) Saturation Voltage - (V) 0.6 0.4 0.3 ICOLL = 50mA 0.2 ICOLL = 20mA 0.1 0 -50 2 ICOLL = 100mA 1.5 ICOLL = 10mA 1 0.5 ICOLL = 10mA -25 0 25 50 75 100 0 -50 125 (TA) Ambient Temperature - (°C) -25 25 0 50 75 100 125 (TA) Ambient Temperature - (°C) FIGURE 3. — ILIMIT vs. TEMPERATURE WITH EXTERNAL RESISTOR FIGURE 4. — REFERENCE VOLTAGE and 2.505 200 1.4 2.504 190 (VREF) Reference Voltage - (V) 1.5 1.2 O ILIMIT (Normalized) 1.3 1.1 1 0.9 0.8 0.7 0.6 0.5 -50 170 IREF 2.502 160 2.501 150 140 2.50 VREF 2.499 130 120 2.498 110 2.497 100 2.496 -25 0 25 50 75 100 (TA) Ambient Temperature - (°C) 6 180 2.503 125 2.495 2.5 (IREF) Reference Current - (nA) REFERENCE CURRENT vs. V+ 90 80 2.7 2.9 3.1 3.3 3.5 V+ (V) Copyright © 1997 Rev. 1.2a 8/04 PRODUCT DATABOOK 1996/1997 LX1431 PROGRAMMABLE R EFERENCE P D R O D U C T I O N A T A S H E E T CHARACTERISTIC CURVES FIGURE 5. — REFERENCE VOLTAGE and FIGURE 6. — 2.5V REFERENCE IK vs. VKA REFERENCE CURRENT vs. V+ 2.502 200 2.50 2.498 2.497 2.496 2.495 2.494 2.493 2.492 2.491 2.490 1000 180 900 170 160 150 140 VREF 130 120 110 100 0 15 10 5 20 25 30 35 800 700 IK - (µA) 2.499 190 (IREF) Reference Current - (nA) IREF bs ol et e (VREF) Reference Voltage - (V) 2.501 600 500 400 300 200 90 100 80 0 0 40 0.5 1.0 1.5 2.0 2.5 3.0 VKA - (V) V+ (V) FIGURE 6. — REFERENCE VOLTAGE and REFERENCE CURRENT vs. TEMPERATURE 2.51 1 0.6 0.4 0.2 IREF 2.495 0 -0.2 2.49 -0.4 -0.6 2.485 (IREF) Reference Current - (nA) 2.5 VREF O (VREF) Reference Voltage - (V) 0.8 2.505 -0.8 2.48 -50 -25 0 25 50 75 100 -1 125 (TA) Temperature - (°C) Pentium is a registered trademark of Intel Corporation. Copyright © 1997 Rev. 1.2a 8/04 7