Microsemi Corporation LX1668CPW, LX1668CDW Datasheet

LIN DOC #:

1668

LX1668

PROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER

T HE I NFINITE P OWER OF I NNOVATION

DESCRIPTION KEY FEATURES

The LX1668 is a Monolithic Switching
Regulator Controller IC designed to pro-

vide 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. It provides a programmable
switching regulator output, together with one
internal linear low dropout regulator and one
adjustable linear regulator driver. The LX1668
offers a triple-output single-chip power sup­ply for Pentium

®

II and other processors.

Programmable Synchronous Rectifier

Driver for CPU Core. The main output is

adjustable from 1.3 to 3.5V using a TTL­compatible 5-bit digital code to meet Intel
specifications. The IC can read the signal
from a DIP-switch, hardwired to Pentium II
processor’s pins or from software. 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. The
device can drive dual MOSFET’s resulting in
typical efficiencies of 85 – 90%, even with
loads in excess of 10A.

NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.

Internal Low Dropout [LDO] Regulator

provides a fixed 2.5V output for powering the
clock circuit at up to 250mA.

External Linear Regulator Driver out­put can be connected to a MOSFET to provide
a high-current adjustable LDO function suit­able for supplying the GTL+ bus circuitry on
a Pentium II processor motherboard at 1.5V.

Short-circuit Current Limiting without
Expensive Current Sense Resistors. The

current sensing mechanism can use a PCB
trace resistance or the parasitic resistance of
the main inductor. For applications requiring
a high degree of accuracy, a conventional
sense resistor can be used.

Ultra-Fast Transient Response Re­duces System Cost. The fixed frequency

modulated off-time architecture results in the
fastest transient response for a given inductor.
Small Package Size. The LX1668 is available
in an economical 20-pin wide body SOIC or
a space-saving 20-pin TSSOP package.

P RODUCTION DAT A SHEET

■ 5-Bit Programmable Output For CPU Core

Supply

■ Internal Fixed 2.5V Low Dropout Regulator

■ Adjustable Linear Regulator Driver

■ Complete Single-Chip Power Solution For

Pentium II Processors

■ No Sense Resistor Required For Short-Circuit

Current Limiting

■ Soft-Start And Hiccup-Mode Current Limiting

Functions

■ Modulated Constant Off-Time Control

Mechanism For Fast Transient Response And
Simple System Design

■ Power Good Flag

■ Over-Voltage Pin & SCR

■ Digital-Compatible Inputs (Including VID Pins)

■ Output Disable Function Shuts Off PWM While

Keeping 2.5V LDO Active - Compatible With
"Green PC" And "Instant On" Requirements

■ Compatible to VRM8.2 - 8.4 Specifications

APPLICATIONS

■ Pentium II & Pentium III Processor Supplies

■ Voltage Regulator Modules

■ General Purpose And Microprocessor DC:DC

Supplies

PRODUCT HIGHLIGHT

5V

L2

1µH

PGND

BDRV
AGND
SS/EN

V

V

CORE

PWRGD

OVP
VID4
VID3

C2

L1

2.5µH

Q2

IRL3303

1500µFx3

2.5mΩ

R

SENSE

Q1

IRL3102

20

19

18

17

C

0.1µF

SS

16

FB

15

14

13

12

11

PWRGD

VID4
VID3
VID2
VID1

V

OUT2

2.5V

3.3V

V

OUT3

1.5V

C5

22µF

330µF

C8

1µF

C4

C6

330µF

C3

1µF

C9

1µF

R1, 0

R2, 50k

Q3

IRLZ44

12V

C7

1µF

1

TDRV

2

V

CC12

3

V

CC5

4

V

OUT2

5

V

CC3

L

DRV

L

FB

VID0
VID1
VID2

LX1668

6

7

8

9

10

VID0

PACKAGE ORDER INFORMATION

T

(°C)

A

Plastic SOWB

DW

20-pin

Plastic TSSOP

PW

20-pin

0 to 70 LX1668CDW LX1668CPW

Note: All surface-mount packages are available in Tape & Reel, append the letter "T" to part number. (i.e. LX1668CPWT)

2N6504

R3
10k

3.3V / 5V

Q4*

SCR

CPU Core

V

CORE

C1

1500µF x 6

*

Q4 optional

OVP crowbar

Copyright © 1999
Rev. 1.0 4/99

L INF INITY MICROELECTRONICS INC.

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: [phone]

1

LX1668

PRODUCT DATABOOK 1996/1997

PROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER

RODUCTION DATA SHEET

P

ABSOLUTE MAXIMUM RATINGS (Note 1 & 2)

12V Supply Voltage (V
5V Supply Voltage (V
Supply Voltage (Internal LDO)/(V

Output Drive Peak Current Source (500ns)....................................................... 1.0A

) .................................................................................. 18V

CC12

) ....................................................................................... 7V

CC5

) ................................................................... 7V

CC3

Output Drive Peak Current Sink (500ns) ........................................................... 1.0A

Input Voltage (SS, VID[0:4]) ................................................................... -0.3V to 6V

Operating Junction Temperature .................................................................... 150°C

Storage Temperature Range ........................................................... -65°C to +150°C

Lead Temperature (Soldering, 10 Seconds) .................................................... 300°C

Note 1. Exceeding these ratings could cause damage to the device. All voltages are with

Note 2. V

respect to Ground. Currents are positive into, negative out of the specified
terminal.

supply is used as input to internal low dropout regulator. Voltages above

CC3

3.3V will cause increased thermal dissipation in the package. Power dissipation
should be limited to keep junction temperature below maximum rating.

THERMAL DATA

DW PACKAGE:

D

x θ

θθ

θ

θθ

JA

θθ

θ

θθ

JA

).

JA

85°C/W

110°C/W

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

PW PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

Junction Temperature Calculation: TJ = TA + (P
The θ

numbers are guidelines for the thermal performance of the device/pc-board

JA

system. All of the above assume no ambient airflow.

PACKAGE PIN OUTS

TDRV

V

V

VID0
VID1
VID2

DW PACKAGE — 20-Pin

TDRV

V

CC12

V

CC5

V

OUT2

V

CC3

L

DRV

L

FB

VID0
VID1
VID2

PW PACKAGE — 20-Pin

1 20
219

CC12

V

318

CC5

417

OUT2

V

516

CC3

L

615

DRV

L

714

FB

813
912
10 11

(Top View)

1 20
219
318
417
516
615
714
813
912
10 11

(Top View)

PGND
BDRV
AGND
SS/ENABLE
V

FB

V

CORE

PWRGD
OVP
VID4
VID3

PGND
BDRV
AGND
SS/ENABLE
V

FB

V

CORE

PWRGD
OVP
VID4
VID3

2

Copyright © 1999

Rev. 1.0 4/99

PRODUCT DATABOOK 1996/1997

PROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER

P RODUCTION DAT A SHEET

ELECTRICAL CHARACTERISTICS

(

Unless otherwise specified, 4.75V < V

T = 25°C.

)

Parameter

Reference & DAC

Initial Accuracy V

Cumulative Regulation Accuracy 1.3V ≤ V

Timing

Off Time OT V
Swicthing Frequency Freq V

Error Comparator / CS-

Input Bias Current I

E

Delay to Output Overdrive ≤ 5mV

C

Current Sense +

Input Resistance R
Pulse By Pulse Current Limit V

Current Sense Delay To Output Overdrive ≤ 5mV

Output Drivers

Drive Rise Time, Fall Time T
Drive High V

Drive Low V

UVLO and Soft-Start (SS)

V

Start-Up Threshold V

CC5

Hysteresis

SS Resistor R

SS Output Enable V
Hiccup Duty Cycle DC

Supply Current

V

Dynamic Supply Current I

CC12

Static Supply Current 12V I

5V I

3.3V I

Power Good / Over-Voltage Protection (OVP)

Threshold (V

Hysteresis
Power Good Voltage Low I

Over-Voltage Threshold (V
OVP Sourcing Current V

Fixed Linear Regulator (V

OUT2

Voltage Reference Tolerance V

Regulation -10mA ≤ I

Current Limit V

Linear Regulator Controller

Voltage Reference Tolerance V
Source Current I

Sink Current I

VID Pins

Low Input VILInternally pulled up to V

High Input V

< 5.25V and 10.8V < V

CC5

Symbol

CORE

FB

CORE

CLP

RF

DHISOURCE

DLISINK

ST

SS

EN

HICCSS

CD

VCC12VSS

VCC5VSS

VCC3VSS

)

LDRVILDRV

LDRV

IH

< 13.2V, 0°C ≤ TA ≤ 70°C. Test conditions: V

CC12

Test Conditions

(Less 40mV output adaptive positioning)

≤ 3.5V

CORE

= 2.0V

CORE

= 1.3V to 3.5V

CORE

1.0V < VSS = VFB < 3.5V

0V < VFB = V

CL = 3000pF

= 20mA

= 20mA

V

> 3.9V

CC12

= 0.1µF, V

Out Freq = 200kHz, CL = 3000pF, Synch., VSS > 0.5V

< 0.5V

< 0.5V

< 0.5V

/ V

CORE

(V

/ V

CORE

= 4mA

PWRGD

/ V

CORE

= 2.0V

OVP

= 2.5V, C

OUT2

≤ 2V

OUT2

= 1.5V, C

LFB

flows from V

) V

SET

) V

SET

), V

SET

OUT2

< 3.5V

CORE

= 2.00V, F

DAC

rising, V

CORE

falling, V

CORE

rising

CORE

= 220µF

OUT

≤ -150mA

= 330µF

OUT

CC12

= 100Hz

REQ

OUT2

OUT2

thru 30k

CC5

≥ 2.0V

≥ 2.0V

,

1.3V ≤ V

≤ 35V, T = 25°C

CORE

LX1668

= V

, V

CC3

Min. Typ. Max.

-1 +1 %

-1.5 1.5 %

45 60 mV

10 11 V

3.9 4.2 4.6 V

0.4 0.5 V

108 110 111 %

90 91 92 %

110 117 125 %

35 60 mA

-2.3 +2.0 %

-1 +1 %

250 mA

-2.3 +1.5 %
30 mA

2.0 V

= 5V, V

CC5

CC5

CC12

LX1668

2.4 µs

250 kHz

-0.3 -1 µ A

100 ns

12 kΩ

100 ns

100 ns

0.1 V

0.10 V

18 kΩ

10 %

24 mA

69mA

13 18 mA

0.4 2 mA

2%

0.5 0.7 V

0.2 mA

0.8 V

= 12V,

Units

Copyright © 1999
Rev. 1.0 4/99

3

LX1668

PRODUCT DATABOOK 1996/1997

PROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER

RODUCTION DATA SHEET

P

ELECTRICAL CHARACTERISTICS

Table 1 - Adaptive Transient Voltage Output (Output Voltage Setpoint — Typical)

Processor Pins

0 = Low, 1 = High

VID4 VID3 VID2 VID1 VID0

011111.34V 1.30V

011101.39V 1.35V

011011.44V 1.40V

011001.49V 1.45V

010111.54V 1.50V

010101.59V 1.55V

010011.64V 1.60V

010001.69V 1.65V

001111.74V 1.70V

001101.79V 1.75V

001011.84V 1.80V

001001.89V 1.85V

000111.94V 1.90V

000101.99V 1.95V

000012.04V 2.00V

000002.09V 2.05V

111112.04V 2.00V

111102.14V 2.10V

111012.24V 2.20V

111002.34V 2.30V

110112.44V 2.40V

110102.54V 2.50V

110012.64V 2.60V

110002.74V 2.70V

101112.84V 2.80V

101102.94V 2.90V

101013.04V 3.00V

101003.14V 3.10V

100113.24V 3.20V

100103.34V 3.30V

100013.44V 3.40V

100003.54V 3.50V

* Nominal = DAC setpoint voltage with no adaptive output voltage positioning.

Output Voltage (V

0.0A

Nominal Output* (V

SET

)

)

SET

Note:

Adaptive Transient Voltage Output

In order to improve transient response a 40mV offset is built into the voltage comparator. At high currents, the
peak output voltage will be lower than the nominal set point , as shown in Figure 4. The actual output voltage
will be a function of the sense resistor, output current and output ripple.

4

Copyright © 1999

Rev. 1.0 4/99

PRODUCT DATABOOK 1996/1997

PROGRAMMABLE MULTIPLE OUTPUT DC:DC CONTROLLER

P RODUCTION DAT A SHEET

CHARACTERISTICS CURVES

LX1668

100

95

90

85

EFFICIENCY (%)__

80

EFFICIENCY A T 3. 1V
EFFICIENCY A T 2. 8V

75

70

123456 7891011121314

EFFICIENCY A T 1. 8V

I

OUT

(A)

FIGURE 1 — Efficiency Test Results:

V

CORE

60mV

40mV

= 5V

IN

V

FB

16

CS Comp

Error Comp

Hiccup

2.5V

V

Non-Synchronous Operation, V

15

+5V

5

V

CC3

4

V

OUT2

6

L

DRV

PWRGD

OVP

VID[0:4]

7

L

FB

14

Power Good

& OVP

13

V

REF

8

9
10
11
12

OUT3

DAC

2.5V

1.5V

R

SS

20k

V

SET

100

95

90

85

EFFICIENCY (%)__

80

75

70

1234567891011121314

BLOCK DIAGRAM

R

SQ

Set

PWM

Q

Off-Time

Control

I

RESET

V

RESET

Hiccup

EFFICIENCY AT 3.1V
EFFICIENCY A T 2.8V
EFFICIENCY A T 1.8V

I

(A)

OUT

FIGURE 2 — Efficiency Test Results:

Synchronous Operation, VIN = 5V

+12V

VIN (5V)

2

V

CC12

1

TDRV

19

BDRV

20

PGND

18

AGND

+5V

UVLO

UVLO

3

V

CC5

C

IN

R

SENSE

L

V

CORE

ESR

C

OUT

Copyright © 1999
Rev. 1.0 4/99

SS/ENABLE

17

C

SS

FIGURE 3 — Block Diagram

5