MAX1965TEEP-T Maxim Integrated, MAX1965TEEP-T Datasheet

MAX1965TEEP-T

Manufacturer Part Number

MAX1965TEEP-T

Description

Current & Power Monitors & Regulators

Manufacturer

Maxim Integrated

Datasheet

1.MAX1965TEEP.pdf (30 pages)

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19-2084; Rev 0; 7/01

The MAX1964/MAX1965 power-supply controllers are

designed to address cost-sensitive applications

demanding voltage sequencing/tracking, such as

cable modem consumer premise equipment (CPE),

xDSL CPE, and set-top boxes. Operating off a low-cost,

unregulated DC supply (such as a wall adapter output),

the MAX1964 generates three positive outputs and the

MAX1965 generates four positive outputs and one neg-

ative output to provide an inexpensive system power

supply.

The MAX1964 includes a current-mode synchronous

step-down controller and two positive regulator gain

blocks. The MAX1965 has one additional positive gain

block and one negative regulator gain block. The main

synchronous step-down controller generates a high-

current output that is preset to 3.3V or adjustable from

1.236V to 0.75

The 200kHz operating frequency allows the use of low-

cost aluminum-electrolytic capacitors and low-cost

power magnetics. Additionally, the MAX1964/MAX1965

step-down controllers sense the voltage across the low-

side MOSFET’s on-resistance to efficiently provide the

current-limit signal, eliminating the need for costly cur-

rent-sense resistors.

The MAX1964/MAX1965 generate additional supply

rails at low cost. The positive regulator gain blocks use

an external PNP pass transistor to generate low voltage

rails directly from the main step-down converter (such

as 2.5V or 1.8V from the main 3.3V output) or higher

voltages using coupled windings from the step-down

converter (such as 5V, 12V, or 15V). The MAX1965’s

negative gain block uses an external NPN pass transis-

tor in conjunction with a coupled winding to generate

-5V, -12V, or -15V.

All output voltages are externally adjustable, providing

maximum flexibility. During startup, the MAX1964 fea-

tures voltage sequencing and the MAX1965 features

voltage tracking. Both controllers provide a power-

good output that monitors all of the output voltages.

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Typical Operating Circuit appears at end of data sheet.

xDSL, Cable, and ISDN Modems

Set-Top Boxes

Wireless Local Loop

________________________________________________________________ Maxim Integrated Products

with an external resistive-divider.

General Description

Tracking/Sequencing Triple/Quintuple

Applications

Power-Supply Controllers

o 4.5V to 28V Input Voltage Range

o Master DC-DC Step-Down Converter:

o Two (MAX1964)/Four (MAX1965) Analog Gain

o Power-Good Indicator

o Voltage Sequencing (MAX1964) or Tracking

MAX1964TEEE

MAX1965TEEP

TOP VIEW

COMP

Blocks:

(MAX1965)

POK

OUT

FB2

FB3

Preset 3.3V or Adjustable (1.236V to 0.75 x V

Output Voltage

Fixed Frequency (200kHz) PWM Controller

No Current-Sense Resistor

Adjustable Current Limit

95% Efficient

Soft-Start

Positive Analog Blocks Drive Low-Cost PNP

Pass Transistors to Build Positive Linear

Regulators

Negative Analog Block (MAX1965) Drives a

Low-Cost NPN Pass Transistor to Build a

Negative Linear Regulator

PA RT

16-Pin QSOP

MAX1964

-40°C to +85°C

RANGE

TEMP.

Ordering Information

BST

GND

ILIM

Pin Configurations

COMP

POK

OUT

FB2

FB3

FB4

PIN-

PACKAGE

16 QSOP

20 QSOP

20-Pin QSOP

MAX1965

Features

(kHz)

200

OSC

BST

GND

ILIM

FB5

)

Related parts for MAX1965TEEP-T

MAX1965TEEP-T Summary of contents

Page 1

... Negative Analog Block (MAX1965) Drives a Low-Cost NPN Pass Transistor to Build a Negative Linear Regulator o Power-Good Indicator o Voltage Sequencing (MAX1964) or Tracking (MAX1965) Ordering Information TEMP RANGE MAX1964TEEE -40°C to +85°C MAX1965TEEP -40°C to +85°C Pin Configurations TOP VIEW POK COMP ...

Page 2

... Mode) Current-Limit Threshold V VALLEY (External Mode) Switching Frequency Dual Mode is a trademark of Maxim Integrated Products, Inc. 2 _______________________________________________________________________________________ Continuous Power Dissipation (T 16-Pin QSOP (derate 8.3mW/°C above +70°C)...........666mW 20-Pin QSOP (derate 9.1mW/°C above +70°C)...........727mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150° ...

Page 3

Tracking/Sequencing Triple/Quintuple ELECTRICAL CHARACTERISTICS (V = 12V, ILIM = FB = GND BST LX PARAMETER SYMBOL Maximum Duty Cycle Soft-Start Period Soft-Start Step Size FB Power-Up Sequence Threshold DH Output Low Voltage DH Output High Voltage ...

Page 4

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers ELECTRICAL CHARACTERISTICS (continued 12V, ILIM = FB = GND BST LX PARAMETER SYMBOL THERMAL PROTECTION (NOTE 3) Thermal Shutdown Thermal Shutdown Hysteresis ELECTRICAL CHARACTERISTICS (V = 12V, ILIM = FB ...

Page 5

Tracking/Sequencing Triple/Quintuple ELECTRICAL CHARACTERISTICS (continued 12V, ILIM = FB = GND BST LX PARAMETER SYMBOL NEGATIVE ANALOG GAIN BLOCK FB5 Regulation Voltage FB5 anscond uctance POWER GOOD ...

Page 6

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers (Circuit of Figure 12V 3.3V OUT OUPUT VOLTAGE vs. LOAD CURRENT (ADJUSTABLE MODE) 5.05 5.03 5.01 4.99 4.97 4.95 0 0.5 1.0 1.5 2.0 LOAD CURRENT (A) SWITCHING WAVEFORMS ...

Page 7

Tracking/Sequencing Triple/Quintuple (Circuit of Figure 12V 3.3V OUT MAX1965 STARTUP WAVEFORM (VOLTAGE TRACKING) MAX1964/65 toc10 -2V - 400µs/div = 1.8V/div 5.0V, 2V/div D. V OUT4 ...

Page 8

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers (Circuit of Figure 12V 3.3V OUT POSITIVE LINEAR REGUALTOR OUTPUT VOLTAGE vs. LOAD CURRENT (Q = TIP30) LDO 2.50 2. 5.0V SUP(POS) 2. 3.3V SUP(POS) ...

Page 9

Tracking/Sequencing Triple/Quintuple (Circuit of Figure 12V 3.3V OUT PIN NAME MAX1964 MAX1965 1 1 POK 2 2 COMP 3 3 OUT FB2 _______________________________________________________________________________________ Power-Supply Controllers ...

Page 10

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers PIN NAME MAX1964 MAX1965 FB3 — — 10 FB4 — — 12 FB5 9 13 ILIM 10 14 GND ...

Page 11

Tracking/Sequencing Triple/Quintuple C1 1µF C2 1µF R POK 100kΩ TO LOGIC R COMP 5MΩ COMP1 COMP2 470pF 47pF C : 1000µF, 10V SANYO (CZ SERIES) OUT Figure 1. MAX1964 Standard Application Circuit Detailed Description The MAX1964/MAX1965 power-supply controllers ...

Page 12

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers negative gain block can be used in conjunction with a coupled winding to generate -5V, -12V, or -15V. DC-DC Controller The MAX1964/MAX1965 step-down converters use a pulse-width-modulated (PWM) current-mode control scheme (Figure 2). An internal transconductance ...

Page 13

Tracking/Sequencing Triple/Quintuple COMP OUT FB 100mV 0.9V REF FB2 B2 0.9V REF FB3 B3 0.9V Figure 2a. MAX1964 Functional Diagram ______________________________________________________________________________________ Power-Supply Controllers MAX1964 ENABLE ∑ SOFT- START REF 1.24V CLK ENABLE REF BIAS OK ...

Page 14

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers COMP OUT FB 100mV 0.9V REF FB_ B_ 0.9V REF B5 FB5 Figure 2b. MAX1965 Functional Diagram 14 ______________________________________________________________________________________ MAX1965 ENABLE ∑ SOFT- START REF 1.24V CLK OUT ENABLE 500mV BIAS ...

Page 15

Tracking/Sequencing Triple/Quintuple Figure 3. “Valley” Current-Limit Threshold Point The DL low-side drive waveform is always the comple- ment of the DH high-side drive waveform (with con- trolled dead time to prevent cross-conduction or “shoot-through”). A dead-time circuit monitors the DL ...

Page 16

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers during startup. The soft-start period is 1024 clock cycles (1024/f ), and the internal soft-start DAC OSC ramps up the voltage in 64 steps. The output reaches regulation when soft-start is completed, regardless of output capacitance ...

Page 17

Tracking/Sequencing Triple/Quintuple C COMP1 * FOR OUTPUT VOLTAGES > 5V, SEE "OUTPUT VOLTAGE SELECTION." Figure 4. Adjustable Output Voltage Find a low-loss inductor having the lowest possible DC resistance that fits in the allotted dimensions. Ferrite cores are often the ...

Page 18

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers current-sense range. For a good compromise between efficiency and cost, choose a high-side MOSFET (N that has conduction losses equal to the switching loss the optimum input voltage. Check to ensure that the conduction ...

Page 19

Tracking/Sequencing Triple/Quintuple ( V V OUT RMS LOAD has a maximum value when the input voltage RMS equals twice the output voltage ( /2. For most applications, nontanta- RMS(MAX) LOAD ...

Page 20

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers OUT REF VEA = I PEAK V R OUT NOMINAL where V = 1.24V the current-sense amplifi- REF VCS er’s gain (4.9 typ the DC ...

Page 21

Tracking/Sequencing Triple/Quintuple • With the output pole’s frequency and series com- pensation capacitor values, the required series resistance can be determined. Based on the above equation, select R = 5.1MΩ. COMP • Now we must determine if the selected output ...

Page 22

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers C1 1µF C2 1µF R POK 100kΩ TO LOGIC R COMP 412kΩ COMP1 COMP2 1500pF 68pF S(NEG) D3 NIHON EC10QS10 C10 47µF C11 1µ BE5 BE5 2200pF 220Ω ...

Page 23

Tracking/Sequencing Triple/Quintuple current and load resistance, the total DC loop gain ( approximately: V(LDO)     BIAS FE ≈  +    V LDO ( )   ...

Page 24

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers Figure 7. Base-Drive Noise Reduction  LOAD ≤ C  BE ƒ  2π POLE CBE ( ) where C is the transistor’s input capacitance, and ...

Page 25

Tracking/Sequencing Triple/Quintuple shown in Figure 8, a series RC snubber circuit at the diode increases the damping factor, allowing the ring- ing to settle quickly. Applications with multiple trans- former windings require only one snubber circuit on the highest output ...

Page 26

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers IN C1 1µ 1µF ILIM R POK 100kΩ TO LOGIC POK R COMP 200kΩ COMP C COMP 8.2nF Figure 8. MAX1964 High-Voltage Application Requires Snubber Circuit Output Filtering for Analog Circuits Some applications need ...

Page 27

Tracking/Sequencing Triple/Quintuple a) POSITIVE OUTPUT VOLTAGE WITH CASCODED BASE DRIVE b) NEGATIVE OUTPUT VOLTAGE (MAX1965 ONLY) WITH CASCODED BASE DRIVE Figure 9. High-Voltage Linear Regulation where the R is the inductor’s DC resistance and DCR R is the output filter ...

Page 28

Tracking/Sequencing Triple/Quintuple Power-Supply Controllers POK TO LOGIC R COMP C C COMP1 COMP2 Figure 10. Filtered Output for Analog Circuits Table 1. Component Suppliers SUPPLIER INDUCTORS & TRANSFORMERS Coilcraft Coiltronics ICE Components Sumida USA Toko CAPACITORS AVX ...

Page 29

Tracking/Sequencing Triple/Quintuple IN VL ILIM MAX1964 MAX1965 POK COMP ______________________________________________________________________________________ Power-Supply Controllers Typical Operating Circuit INPUT BST DH MAIN OUTPUT LX DL OUT GND FB B2 OUT #2 FB2 29 ...

Page 30

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 30 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products ...

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