LX1662A MICROSEMI [Microsemi Corporation], LX1662A Datasheet

LX1662A

Manufacturer Part Number

LX1662A

Description

SINGLE-CHIP PROGRAMMABLE PWM CONTROLLERS WITH 5-BIT DAC

Manufacturer

MICROSEMI [Microsemi Corporation]

Datasheet

1.LX1662A.pdf (15 pages)

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H E

The LX1662/62A and LX1663/63A are

Monolithic Switching Regulator Con-

troller IC’s designed to provide a low cost,

high performance adjustable power supply

for advanced microprocessors and other

applications requiring a very fast transient

response and a high degree of accuracy.

out Expensive Current Sense Resistors.

Current-sensing mechanism can use PCB

trace resistance or the parasitic resistance of

the main inductor.

LX1663A have reduced current sense com-

parator threshold for optimum perfor-

mance using a PCB trace. For applications

requiring a high degree of accuracy, a

conventional sense resistor can be used to

sense current.

fier Driver for CPU Core.

output is adjustable from 1.3V to 3.5V using

a 5-bit code. The IC can read a VID signal

set by a DIP switch on the motherboard, or

hardwired into the processor’s package (as

in the case of Pentium

processors). The 5-bit code adjusts the

output voltage between 1.30 and 2.05V in

50mV increments and between 2.0 and 3.5V

in 100mV increments, conforming to the

IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.

Short-Circuit Current Limiting with-

Programmable Synchronous Recti-

N F I N I T E

Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. LX1662CDT)

11861 W

The LX1662A and

O W E R

Pro and Pentium II

VID0

VID1

VID2

VID3

VID4

ESTERN

Plastic DIP

14-pin

The main

O F

0.1µF

I N

VENUE

N N O V A T I O N

I N I T Y

, G

Intel Corporation specification. The device

can drive dual MOSFET’s resulting in typical

efficiencies of 85 - 90% even with loads in

excess of 10 amperes. For cost sensitive

applications, the bottom MOSFET can be

replaced with a Schottky diode (non-syn-

chronous operation).

available in a narrow body 14-pin surface

mount IC package for space sensitive appli-

cations. The LX1663 provides the additional

functions of Over Voltage Protection (OVP)

and Power Good (PWRGD) output drives

for applications requiring output voltage

monitoring and protection functions.

duces System Cost. The modulated off-

time architecture results in the fastest tran-

sient response for a given inductor, reduc-

ing output capacitor requirements, and re-

ducing the total regulator system cost.

Good Flag. The OVP output in the LX1663

& LX1663A can be used to drive an SCR

crowbar circuit to protect the load in the

event of a short-circuit of the main MOSFET.

The LX1663 & LX1663A also have a logic-

level Power Good Flag to signal when the

output voltage is out of specified limits.

ARDEN

14-pin, Narrow Body SOIC

Smallest Package Size. The LX1662 is

Ultra-Fast Transient Response Re-

Over-Voltage Protection and Power

INV

VID0

VID1

VID2

VID3

CC_CORE

LX1662

Plastic DIP

16-pin

ROVE

I C R O E L E C T R O N I C S

, CA. 92841, 714-898-8121, F

BDRV

TDRV

GND

VID4

12V

LX1662/62A, LX1663/63A

1µF

680pF

Plastic SOIC

14-pin

IRL3102

1µH

IRL3303

6.3V

1500µF x3

, 2.5µH

N C

** Three capacitors for Pentium

Four capacitors for Pentium II

I 5-bit Programmable Output For CPU Core

I No Sense Resistor Required For Short-

I Designed To Drive Either Synchronous Or

I Lowest System Cost Possible For Price-

I Soft-Start Capability

I Modulated, Constant Off-Time Architecture

I Available Over-Voltage Protection (OVP)

I Small, Surface-Mount Packages

I Socket 7 Microprocessor Supplies

I Pentium II and Deschutes Processor & L2-

I Voltage Regulator Modules

I General Purpose DC:DC Converter

6.3V, 1500µF x 3**

: 714-893-2570

Supply

Circuit Current Limiting

Non-Synchronous Output Stages

Sensitive Pentium And Pentium II Class

Applications

For Fast Transient Response And Simple

System Design

Crowbar Driver And Power Good Flag

(LX1663 only)

(including Intel Pentium Processor, AMD-

Processors)

Cache Supplies

Applications

And Cyrix

Plastic SOIC

16-pin

2.5m9

6x86

L I N D

Supply Voltage

for CPU Core

, Gx86

O C

and M2

# :

OUT

Related parts for LX1662A

LX1662A Summary of contents

Page 1

... Expensive Current Sense Resistors. Current-sensing mechanism can use PCB trace resistance or the parasitic resistance of the main inductor. The LX1662A and LX1663A have reduced current sense com- parator threshold for optimum perfor- mance using a PCB trace. For applications requiring a high degree of accuracy, a conventional sense resistor can be used to sense current ...

Page 2

LX1662/62A, LX1663/63A Supply Voltage (V ) .................................................................................................... 25V C1 Supply Voltage (V ) .................................................................................................... 15V CC Output Drive Peak Current Source (500ns) ............................................................... 1.5A Output Drive Peak Current Sink (500ns) ................................................................... 1.5A Input Voltage (SS, INV CC_CORE ...

Page 3

... Input Offset Voltage Delay to Output C Current Sense Section Input Bias Current (V Pin) I CC_CORE B Pulse By Pulse C LX1662/1663 V L CLP LX1662A/1663A C Delay to Output S Output Drivers Section Drive Rise Time T R Drive Fall Time T F Drive High V DH Drive Low V DL Output Pull Down ...

Page 4

LX1662/62A, LX1663/63A * Nominal = DAC setpoint voltage with no adaptive output voltage positioning. Note: Adaptive Transient Voltage Output In order to improve transient response a 40mV offset is built into the Current Sense comparator. At high currents, the peak ...

Page 5

Output Set Point EFFICIENCY AT 3.1V EFFICIENCY AT 2.8V 75 EFFICIENCY AT 1. (A) OUT FIGURE 2 — Efficiency Test Results: Non-Synchronous Operation, V ...

Page 6

... FIGURE 5 — Block Diagram PWM Latch DOM R Q Break Before Make 0.7V SYNC EN Comp OV Comp UV Comp LX1663/1663A ONLY Note: Pin numbers are correct for LX1663/1663A, 16-pin package. * Not connected on the LX1662/1662A. ** 60mV in LX1662A & LX1663A TDRV 15 GND 14 BDRV OV* 10 PWRGD* 9 ...

Page 7

Pin LX1662 LX1663 Name Pin # Pin # Description Soft-Start pin, internally connected to the non-inverting input of the error comparator. Inverting input of the error comparator. Output voltage. Connected to non-inverting input of the current-sense comparator. Voltage Identification pin ...

Page 8

LX1662/62A, LX1663/63A IC OPERATION Referring to the block diagram and typical application circuit, the output turns ON the top MOSFET, allowing the inductor current to increase. At the error comparator threshold, the PWM latch is reset, the top MOSFET turns ...

Page 9

C 3 0.1µF U1 LX1662 INV 3 V CC_CORE 4 VID0 VID0 5 VID1 VID1 6 VID2 VID2 7 VID3 VID3 VID4 14-pin, Narrow Body SOIC FIGURE 6 — LX1662 In A Pentium / Pentium II Processor ...

Page 10

LX1662/62A, LX1663/63A C 3 0.1µ VID0 5 VID1 6 VID2 7 VID3 8 VID4 FIGURE 8 — Pentium II Processor Application With OVP, Power Good And Loss-Less Current Sensing (Synchronous 0.1µF LX1663 1 SS ...

Page 11

Ref Description Ω The LX1662/63 devices are very easy to design with, requiring only a few simple calculations to implement a given design. The following procedures and considerations should provide effec- tive operation for virtually all applications. Refer to the ...

Page 12

... The LX166x family offers two different comparator thresholds. The LX1662 & 1663 have a threshold of 100mV, while the LX1662A and LX1663A have a threshold of 60mV. The 60mV threshold is better suited to higher current loads, such as a Pentium II or Deschutes processor ...

Page 13

CURRENT LIMIT (continued) PCB Sense Resistor A PCB sense resistor should be constructed as shown in Figure 10. By attaching directly to the large pads for the capacitor and inductor, heat is dissipated efficiently by the larger copper masses. Connect ...

Page 14

LX1662/62A, LX1663/63A CURRENT LIMIT (continued) In cases where large that the trip point current would L be lower than the desired short-circuit current limit, a resistor (R can be put in parallel with shown ...

Page 15

LAYOUT GUIDELINES - THERMAL DESIGN A great deal of time and effort were spent optimizing the thermal design of the demo boards. Any user who intends to implement an embedded motherboard would be well advised to carefully read and follow ...

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