MAX1865TEEP+ Maxim Integrated Products, MAX1865TEEP+ Datasheet

IC PWR SUPPLY CONTROLLER 20QSOP

MAX1865TEEP+

Manufacturer Part Number
MAX1865TEEP+
Description
IC PWR SUPPLY CONTROLLER 20QSOP
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1865TEEP+

Applications
Power Supply Controller
Voltage - Input
4.5 ~ 28 V
Current - Supply
1.4mA
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
20-QSOP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Supply
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
The MAX1864/MAX1865 power-supply controllers are
designed to address cost-conscious applications 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 MAX1864 generates three positive outputs, and the
MAX1865 generates four positive outputs and one neg-
ative output to provide a cost-effective system power
supply.
The MAX1864 includes a current-mode synchronous
step-down controller and two positive regulator gain
blocks. The MAX1865 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 0.8
divider. The 100kHz/200kHz operating frequency
allows the use of low-cost aluminum-electrolytic capaci-
tors and low-cost power magnetics. Additionally, the
MAX1864/MAX1865 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 current-sense resistors.
The MAX1864/MAX1865 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 MAX1865’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. Additionally, the MAX1864/
MAX1865 feature soft-start for the step-down converter
and all the positive linear regulators, and have a power-
good output that monitors all of the output voltages.
19-2030; Rev 0; 4/01
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.
xDSL, Cable, and ISDN Modems
Set-Top Boxes
Wireless Local Loop
xDSL/Cable Modem Triple/Quintuple Output
________________________________________________________________ Maxim Integrated Products
V
General Description
IN
with an external resistive-
Applications
♦ 4.5V to 28V Input Voltage Range
♦ Master DC-DC Step-Down Converter
♦ Two (MAX1864)/Four (MAX1865) Analog
♦ Power-Good Indicator
♦ Soft-Start Ramp for All Positive Regulators
MAX1864TEEE
MAX1864UEEE
MAX1865TEEP
MAX1865UEEP
Gain Blocks
Pin Configurations continued at end of data sheet.
Preset 3.3V or Adjustable (1.236V to 0.8 ✕ V
Output Voltage
Fixed-Frequency (100kHz/200kHz) PWM
Controller
No Current-Sense Resistor
Adjustable Current Limit
95% Efficient
Positive Analog Blocks Drive Low-Cost PNP
Pass Transistors to Build Positive Linear
Regulators
Negative Analog Block (MAX1865) Drives a
Low-Cost NPN Pass Transistor to Build a
Negative Linear Regulator
TOP VIEW
PART
COMP
POK
OUT
FB2
FB3
FB
B2
B3
Power Supplies
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
1
2
6
3
4
5
7
8
RANGE
Ordering Information
TEMP.
16 QSOP
MAX1864
Pin Configurations
PIN-
PACKAGE
16 QSOP
16 QSOP
20 QSOP
20 QSOP
16
15
14
13
12
11
10
9
IN
VL
BST
DH
LX
DL
GND
ILIM
Features
(kHz)
f
200
100
200
100
OSC
IN
)
1

Related parts for MAX1865TEEP+

MAX1865TEEP+ Summary of contents

Page 1

... Cable, and ISDN Modems Set-Top Boxes Wireless Local Loop ________________________________________________________________ Maxim Integrated Products 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. ♦ 4.5V to 28V Input Voltage Range ♦ ...

Page 2

... VALLEY (Internal Mode) Current-Limit Threshold V VALLEY (External Mode) 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

Modem Triple/Quintuple Output ELECTRICAL CHARACTERISTICS (continued 12V, ILIM = FB = GND BST PARAMETER SYMBOL Switching Frequency Maximum Duty Cycle Soft-Start Period Soft-Start Steps DH Output Low Voltage DH Output High Voltage DL ...

Page 4

Modem Triple/Quintuple Output Power Supplies ELECTRICAL CHARACTERISTICS (V = 12V, ILIM = FB = GND BST LX PARAMETER SYMBOL GENERAL Operating Input Voltage Range V (Note 1) Quiescent Supply Current I VL REGULATOR Output Voltage ...

Page 5

Modem Triple/Quintuple Output ELECTRICAL CHARACTERISTICS (continued 12V, ILIM = FB = GND BST PARAMETER SYMBOL POWER GOOD (POK) OUT Trip Level (Preset Mode) FB Trip Level (Adjustable Mode) FB2, FB3, FB4 Trip Level ...

Page 6

Modem Triple/Quintuple Output Power Supplies (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 2.5 3.0 LOAD ...

Page 7

Modem Triple/Quintuple Output (Circuit of Figure 12V 3.3V OUT POSITIVE LINEAR REGULATOR OUTPUT VOLTAGE vs. LOAD CURRENT (Q = 2N3905) LDO 2.50 2. 5.0V SUP(POS) 2. 3.3V SUP(POS) ...

Page 8

Modem Triple/Quintuple Output Power Supplies (Circuit of Figure 12V 3.3V OUT POSITIVE LINEAR REGULATOR POWER-SUPPLY REJECTION RATIO (Q = TIP30) LDO 150mA 10 ...

Page 9

Modem Triple/Quintuple Output PIN NAME MAX1864 MAX1865 1 1 POK 2 2 COMP 3 3 OUT FB2 FB3 — — 10 FB4 — 11 ...

Page 10

Modem Triple/Quintuple Output Power Supplies PIN NAME MAX1864 MAX1865 9 13 ILIM 10 14 GND BST Detailed Description The MAX1864/MAX1865 power-supply controllers ...

Page 11

Modem Triple/Quintuple Output IN C1 1μ 1μF ILIM R POK 100kΩ POK FB R COMP 47kΩ COMP C COMP 8.2nF Figure 1. Standard MAX1864 Application Circuit the voltage across the load. Under overload conditions, when the inductor ...

Page 12

Modem Triple/Quintuple Output Power Supplies MAX1864 MAX1865 COMP OUT FB 100mV FB_ B_ 0.9V REF FB1 0.9V REF OUT B5* FB5* *MAX1865 ONLY Figure 2. Functional Diagram 12 ______________________________________________________________________________________ ENABLE FB1 ∑ SOFT- START ...

Page 13

Modem Triple/Quintuple Output Current-Limit Circuit The current-limit circuit employs a unique “valley” cur- rent-limiting algorithm that uses the low-side MOSFET’s on-resistance as a sensing element (Figure 3). If the voltage across the low-side MOSFET (R ) exceeds the current-limit ...

Page 14

Modem Triple/Quintuple Output Power Supplies Undervoltage Lockout If VL drops below 3.5V, the MAX1864/MAX1865 assume that the supply voltage is too low to make valid decisions, so the undervoltage lockout (UVLO) circuitry inhibits switching, forces POK low, and forces ...

Page 15

Modem Triple/Quintuple Output FOR OUTPUT VOLTAGES > 5V, SEE "OUTPUT VOLTAGE SELECTION." Figure 4. Adjustable Output Voltage where f is 200kHz for MAX186_T and 100kHz for SW MAX186_U. The exact inductor value is not critical and ...

Page 16

Modem Triple/Quintuple Output Power Supplies The MAX1864/MAX1865s’ step-down controller drives two external logic-level N-channel MOSFETs as the cir- cuit switch elements. The key selection parameters are: • On-resistance (R ) DS(ON) • Maximum drain-to-source voltage (V • Minimum threshold ...

Page 17

Modem Triple/Quintuple Output MAX1864 BST MAX1865 R GATE (OPTIONAL BST GATE (OPTIONAL) DH GND Figure 5. Reducing the Switching EMI The key selection parameters for the output capacitor are the actual capacitance value, ...

Page 18

Modem Triple/Quintuple Output Power Supplies OUT REF VEA = I PEAK V R OUT NOMINAL where A is the current-sense amplifier’s gain (4.9 VCS typ the DC gain of the ...

Page 19

Modem Triple/Quintuple Output C1 1μF C2 1μF R POK 100kΩ TO LOGIC R COMP 47kΩ C COMP 8.2nF C15 10nF R10 470Ω BE5 BE5 2200pF 220Ω Q4 TIP29 C12 10μF V OUT5 -12V AT 50mA C11 D4 ...

Page 20

Modem Triple/Quintuple Output Power Supplies Transistor Selection The pass transistors must meet specifications for cur- rent gain (h ), input capacitance, collector-emitter sat- FE uration voltage, and power dissipation. The transistor’s current gain limits the guaranteed maximum output cur- ...

Page 21

Modem Triple/Quintuple Output ƒ ≈ POLE 2π C OUT ESR Do not use output capacitors with more than 200mΩ of ESR. Typically, more output capacitance provides the best solution, since this also reduces the output voltage ...

Page 22

Modem Triple/Quintuple Output Power Supplies only), connect the transformer as shown in Figure 6, where the minimum turns ratio is determined by: ⎛ LDO NEG ( ) SAT ≥ ⎜ ⎜ N NEG V ...

Page 23

Modem Triple/Quintuple Output 5) Ensure all feedback connections are short and direct. Place the feedback resistors as close to the MAX1864/MAX1865 as possible. 6) When trade-offs in trace lengths must be made, it’s preferable to allow the inductor charging ...

Page 24

Modem Triple/Quintuple Output Power Supplies MAX1864 MAX1865 a) POSITIVE OUTPUT VOLTAGE WITH CASCODED BASE DRIVE MAX1865 b) NEGATIVE OUTPUT VOLTAGE (MAX1865 ONLY) WITH CASCODED BASE DRIVE Figure 8. High-Voltage Linear Regulation Table 1. Component Suppliers SUPPLIER INDUCTORS AND TRANSFORMERS ...

Page 25

... 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 25 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products ...

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