MAXIM MAX1964, MAX1965 Technical data

General Description

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 neg­ative 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 high­current output that is preset to 3.3V or adjustable from

1.236V to 0.75 ✕VINwith an external resistive-divider.
The 200kHz operating frequency allows the use of low­cost aluminum-electrolytic capacitors and low-cost
power magnetics. Additionally, the MAX1964/MAX1965
step-down controllers sense the voltage across the low­side MOSFET’s on-resistance to efficiently provide the
current-limit signal, eliminating the need for costly cur­rent-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 transis­tor 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 fea­tures voltage sequencing and the MAX1965 features
voltage tracking. Both controllers provide a power­good output that monitors all of the output voltages.

Applications

xDSL, Cable, and ISDN Modems

Set-Top Boxes

Wireless Local Loop

Features

♦ 4.5V to 28V Input Voltage Range

♦ Master DC-DC Step-Down Converter:

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

IN

)
Output Voltage
Fixed Frequency (200kHz) PWM Controller
No Current-Sense Resistor
Adjustable Current Limit
95% Efficient
Soft-Start

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

Blocks:

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

♦ Power-Good Indicator

♦ Voltage Sequencing (MAX1964) or Tracking

(MAX1965)

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple

Power-Supply Controllers

________________________________________________________________ Maxim Integrated Products 1

Pin Configurations

19-2084; Rev 0; 7/01

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.

Typical Operating Circuit appears at end of data sheet.

Ordering Information

PA RT

MAX1964TEEE

MAX1965TEEP

TEMP.

RANGE

-40°C to +85°C

-40°C to +85°C

PIN­PACKAGE

16 QSOP 200

20 QSOP 200

TOP VIEW

1

POK IN

COMP

2

OUT

3

MAX1964

4

FB

B2

5

FB2

6

B3

7

FB3

8

16-Pin QSOP

16

15

VL

14

BST

13

DH

12

LX

DL

11

10

GND

9

ILIM

POK

COMP

OUT

FB2

FB3

1

2

3

4

FB

5

B2

6

7

B3

8

9

B4

10

MAX1965

20-Pin QSOP

f

OSC

(kHz)

20

19

18

17

16

15

14

13

12

11

IN

VL

BST

DH

LX

DL

GND

ILIM

FB5

B5FB4

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple
Power-Supply Controllers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

IN, B2, B3, B4 to GND............................................-0.3V to +30V

B5 to OUT...............................................................-20V to +0.3V

VL, POK, FB, FB2, FB3, FB4, FB5 to GND ...............-0.3V to +6V

LX to BST..................................................................-6V to +0.3V

BST to GND ............................................................-0.3V to +36V

DH to LX....................................................-0.3V to (V

BST

+ 0.3V)

DL, OUT, COMP, ILIM to GND......................-0.3V to (V

L

+ 0.3V)

VL Output Current ...............................................................50mA

VL Short Circuit to GND..................................................≤ 100ms

Continuous Power Dissipation (T

A

= +70°C)

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°C

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

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(VIN= 12V, ILIM = FB = GND, V

BST

- VLX= 5V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)

)

Dual Mode is a trademark of Maxim Integrated Products, Inc.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

GENERAL

Operating Input Voltage Range
(Note 1)

V

IN

4.5 28 V

VFB = 0, V

Quiescent Supply Current I

VL REGULATOR

Output Voltage VL 6V < VIN < 28V, 0.1mA < I

Line Regulation VIN = 6V to 28V 3.0 %

Undervoltage Lockout Trip Level V

Minimum Bypass Capacitance C

DC-DC CONTROLLER

Output Voltage (Preset Mode) V

Typical Output Voltage Range
(Adjustable Mode) (Note 2)

FB Set Voltage (Adjustable
Mode)

FB Dual-Mode™ Threshold 50 100 150 mV

FB Input Leakage Current I

FB to COMP Transconductance g

Current-Sense Amplifier Voltage
Gain

Current-Limit Threshold
(Internal Mode)

Current-Limit Threshold
(External Mode)

Switching Frequency f

IN

UVLO

BYP(MIN

OUT

V

OUT

V

SET

FB

A

LIM

V

VALLEYVILIM

V

VALLEYVILIM

OSC

V

= V

FB2

= -0.1V

V

FB5

VL rising, 3% hysteresis (typ) 3.2 3.5 3.8 V
10mΩ < ESR < 500mΩ 1 µF

FB = GND 3.272 3.34 3.355 V

FB = COMP 1.221 1.236 1.252 V

VFB = 1.5V 0.01 100 nA

FB = COMP, I

m

VIN - VLX = 250mV 4.46 4.9 5.44 V/V

= 5.0V 190 250 310 mV

= 2.5V 440 530 620 mV

FB3

OUT

= 4V,

= V

= 1.5V,

FB4

= ±5µA 70 100 140 µS

COMP

MAX1964 1.25 2.5

MAX1965 1.5 3.0

<20mA 4.75 5.00 5.25 V

LOAD

V

SET

160 200 240 kHz

0.75 ✕ V

mA

IN

V

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple

Power-Supply Controllers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS

(VIN= 12V, ILIM = FB = GND, V

BST

- VLX= 5V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Maximum Duty Cycle D

Soft-Start Period t

Soft-Start Step Size V

FB Power-Up Sequence
Threshold

DH Output Low Voltage I

DH Output High Voltage I

DL Output Low Voltage I

DL Output High Voltage I
DH On-Resistance High (DH to BST) and low (DH to LX) 1.5 4 Ω

DL On-Resistance

Output Drive Current Sourcing or sinking, VDH or VDL = VL/2 0.5 A

LX, BST Leakage Current V

POSITIVE ANALOG GAIN BLOCKS

FB2, FB3, FB4 Regulation
Voltage

FB2 Power-Up Sequence
Threshold

FB2, FB3, FB4 to B_
Transconductance Error

Feedback Input Leakage
Current

Driver Sink Current IB_

NEGATIVE ANALOG GAIN BLOCK

FB5 Regulation Voltage

FB5 to B5 Tr anscond uctance E r r or ∆V

Feedback Input Leakage Current I

Driver Source Current I

POWER GOOD (POK)

OUT Trip Level (Preset Mode) FB = GND, falling edge, 3% hysteresis (typ) 2.88 3.0 3.12 V

FB Trip Level (Adjustable Mode) Falling edge, 3% hysteresis (typ) 1.070 1.114 1.159 V

FB2, FB3, FB4 Trip Level Falling edge, 3% hysteresis (typ) 1.070 1.114 1.159 V

FB5 Trip Level Rising edge, 35mV hysteresis (typ) 368 530 632 mV

POK Output Low Level I

POK Output High Leakage V

MAX

SOFT

77 82 90 %

1024 1/f

/64 V

REF

MAX1964, FB rising, B2 turns on 1.145 V

= 10mA, measured from DH to LX 40 mV

SINK

= 10m A, m easur ed fr om BS T to D H 40 mV

S OU RC E

= 10mA, measured from DL to GND 20 mV

SINK

= 10m A, m easur ed fr om D L to GN D VL - 0.1 V

S OU RC E

High (DL to VL) 4.3 10

Low (DL to GND) 0.7 2

= VLX = VIN = 28V, VFB = 1.5V 0.04 10 µA

BST

VB2 = VB3 = VB4 = 5V,

= IB3 = IB4 = 1mA (sink)

I

B2

1.226 1.24 1.257 V

MAX1964, FB2 rising, B3 turns on 1.145 V

= VB3 = VB4 = 5V, IB2 = IB3 = IB4 =

V

∆V

FB

I

_V

FB

FB5

FB5

B5

B2

_

0.5mA to 5mA (sink)

= V

FB2

V

= V

FB2

V

= 1.188V

FB4

V

= V

B5

(source)

FB3

FB3

OUT

= V

= 1.5V 0.01 100 nA

FB4

VB2 = VB3 = VB4 = 2.5V 10 21

=

V

= VB3 = VB4 = 4.0V 24

B2

- 2V, V

= 3.5V, IB5 = 1mA

OUT

-20 -5 +10 mV

13 22 mV

VB5 = 0, IB5 = 0.5mA to 5mA (source) -13 -20 mV

V

= -100mV 0.01 100 nA

FB5

V

= 200mV, VB5 = V

FB5

3.5V

= 1mA 0.4 V

SINK

= 5V 1 µA

POK

OUT

- 2.0V, V

OUT

=

10 25 mA

OSC

Ω

mA

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple
Power-Supply Controllers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS

(VIN= 12V, ILIM = FB = GND, V

BST

- VLX= 5V, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 12V, ILIM = FB = GND, V

BST

- VLX= 5V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

THERMAL PROTECTION (NOTE 3)

Thermal Shutdown Rising temperature 160 °C
Thermal Shutdown Hysteresis 15 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

GENERAL

Operating Input Voltage Range
(Note 1)

Quiescent Supply Current I

VL REGULATOR

Output Voltage VL 6V < VIN < 28V, 0.1mA < I

Line Regulation VIN = 6V to 28V 3.0 %

Undervoltage Lockout Trip Level V

DC-DC CONTROLLER

Output Voltage (Preset Mode) V

Feedback Set Voltage
(Adjustable Mode)

Current-Sense Amplifier Voltage
Gain

Current-Limit Threshold
(Internal Mode)

Current-Limit Threshold
(External Mode)

Switching Frequency f

Maximum Duty Cycle D

POSITIVE ANALOG GAIN BLOCKS

FB2, FB3, FB4 Regulation
Voltage

FB2, FB3, FB4 to B_
Transconductance Error

V

IN

VFB = 0, V

IN

UVLO

OUT

V

SET

A

LIM

V

VALLEYVILIM

V

VALLEYVILIM

OSC

MAX

∆V

FB

V
V

VL rising, 3% hysteresis (typ) 3.0 4.0 V

FB = GND 3.247 3.38 V

FB = COMP 1.211 1.261 V

VIN - VLX = 250mV 4.12 5.68 V/V

VB2 = VB3 = VB4 = 5V,
I

V

_

0.5mA to 5mA (sink)

= 4V,

OUT

= V

= V

FB2

FB3

= -0.1V

FB5

= 5.0V 150 350 mV

= 2.5V 400 660 mV

= IB3 = IB4 = 1mA (sink)

B2

= VB3 = VB4 = 5V, IB2 = IB3 = IB4 =

B2

FB4

= 1.5V,

MAX1964 2.5

MAX1965 3.0

<20mA 4.75 5.25 V

LOAD

4.5 28 V

160 240 kHz

74 90 %

1.215 1.265 V

mA

28 mV

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple

Power-Supply Controllers

_______________________________________________________________________________________ 5

Note 1: Connect VL to IN for operation with VIN< 5V.
Note 2: See Output Voltage Selection section.
Note 3: The internal 5V linear regulator (VL) powers the thermal shutdown block. Shorting VL to GND disables thermal shutdown.
Note 4: Specifications to -40°C are guaranteed by design, not production tested.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 12V, ILIM = FB = GND, V

BST

- VLX= 5V, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)

Typical Operating Characteristics

(Circuit of Figure 1, VIN= 12V, V

OUT

= 3.3V, TA= +25°C, unless otherwise noted.)

50

0.01 1010.1

EFFICIENCY vs. LOAD CURRENT

(PRESET MODE)

100

70

60

90

80

MAX1964/65 toc01

LOAD CURRENT (A)

EFFICIENCY (%)

VIN = 6.5V

VIN = 8V

VIN = 12V

VIN = 18V

VIN = 24V

V

OUT

= 3.3V

3.27

3.29

3.28

3.31

3.30

3.32

3.33

0 1.0 1.50.5 2.0 2.5 3.0

OUTPUT VOLTAGE vs. LOAD CURRENT

(PRESET MODE)

MAX1964/65 toc02

LOAD CURRENT (A)

OUTPUT VOLTAGE (V)

50

0.01 1010.1

EFFICIENCY vs. LOAD CURRENT

(ADJUSTABLE MODE)

100

70

60

90

80

MAX1964/65 toc03

LOAD CURRENT (A)

EFFICIENCY (%)

VIN = 6.5V

VIN = 8V

VIN = 12V

VIN = 18V

VIN = 24V

V

OUT

= +5.0V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

NEGATIVE ANALOG GAIN BLOCK

FB5 Regulation Voltage

FB5 to B5 Tr anscond uctance E r r or ∆V

POWER GOOD (POK)

OUT Trip Level (Preset Mode) FB = GND, falling edge, 3% hysteresis (typ) 2.85 3.15 V

FB Trip Level (Adjustable Mode) Falling edge, 3% hysteresis (typ) 1.058 1.17 V

FB2, FB3, FB4 Trip Level Falling edge, 3% hysteresis (typ) 1.058 1.17 V

FB5 Trip Level Rising edge, 35mV hysteresis (typ) 325 675 mV

V

= V

B5

= 1mA (source)

I

B5

VB5 = 0, IB5 = 0.5mA to 5mA (source) -30 mV

FB5

OUT

- 2V, V

OUT

= 3.5V,

-25 +10 mV

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple
Power-Supply Controllers

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, V

OUT

= 3.3V, TA= +25°C, unless otherwise noted.)

1.00.50 1.5 2.0

OUPUT VOLTAGE vs. LOAD CURRENT

(ADJUSTABLE MODE)

MAX1964/65 toc04

LOAD CURRENT (A)

OUTPUT VOLTAGE (V)

4.97

4.99

5.01

4.95

5.03

5.05

4.95

4.97

4.99

5.01

5.03

5.05

0105 15202530

INTERNAL 5V LINEAR REGULATOR

vs. LOAD CURRENT

MAX1964/65 toc05

LOAD CURRENT (mA)

VL (V)

LOAD TRANSIENT

(STEP-DOWN CONVERTER)

MAX1964/65 toc06

5.0V

0

1A

A. V

OUT

= 5V, 100mV/div

B. I

OUT

= 10mA TO 1A, 500mA/div

V

IN

= 12V

B

A

40µs/div

SWITCHING WAVEFORMS

(STEP-DOWN CONVERTER)

MAX1964/65 toc07

5.00V

A. V

OUT

= 5.0V, 50mV/div

B. V

LX

,10V/div

C. INDUCTOR CURRENT, 500mA/div
V

IN

= 12V, R

OUT1

= 5V

B

A

40µs/div

C

4.95V

12V

0

1A

0.5A

SOFT-START

(STEP-DOWN CONVERTER)

MAX1964/65 toc08

5V

A. V

L

= 5V, 5V/div

B. V

OUT1

=

5V (ADJ),2V/div
C. INDUCTOR CURRENT, 1A/div
V

IN

= STEPPED FROM 0 TO 12V, R

OUT1

= 10Ω

B

A

1ms/div

C

0

5V

0

1A

0

MAX1964 STARTUP WAVEFORM

(VOLTAGE SEQUENCING)

MAX1964/65 toc09

5V

A. V

OUT1

= 5V (ADJ), 2V/div

B. V

OUT2

=

1.8V, 1V/div

C. V

OUT3

=

3.3V, 2V/div

D. V

POK

, 5V/div

V

IN

= STEPPED FROM 0 TO 12V, R

OUT1

= 5Ω

B

A

200µs/div

C

1.8V

3.3V

D

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple

Power-Supply Controllers

_______________________________________________________________________________________ 7

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, V

OUT

= 3.3V, TA= +25°C, unless otherwise noted.)

MAX1965 STARTUP WAVEFORM

(VOLTAGE TRACKING)

MAX1964/65 toc10

4V

A. V

OUT4

= 5.0V, 2V/div D. V

OUT3

=

1.8V/div

B. V

OUT1

=

3.3V, 2V/div E. V

OUT5

=

-5.0V, 2V/div

C. V

OUT2

=

2.5V, 2V/div F. V

POK

, 5V/div

V

IN

= STEPPED FROM 0 TO 12V,

R

OUT1

= 6.6Ω

CIRCUIT OF FIGURE 6

B

A

400µs/div

C

2V

0

D

E

F

-2V

-4V

5V

0

0

5

10

15

20

25

30

35

40

0246810

POSITIVE LINEAR REGULATOR BASE-

DRIVE CURRENT vs. BASE-DRIVE VOLTAGE

MAX1964/65 toc11

BASE VOLTAGE (V)

BASE-DRIVE SINK CURRENT (mA)

V

FB_

= 1.0V

V

FB_

= 0.96V

REF

B2, B3 AND B4

(MAX1965) ONLY

2.50

0.01 10.1 100

POSITIVE LINEAR REGULATOR

OUTPUT VOLTAGE vs. LOAD CURRENT

(Q

LDO

= 2N3905)

2.42

2.44

2.46

2.48

MAX1964/65 toc12

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

10 1000

V

SUP(POS)

= 5.0V

V

SUP(POS)

= 3.3V

POSITIVE LINEAR REGULATOR

OUTPUT VOLTAGE vs. SUPPLY VOLTAGE

(Q

2.50

2.48

2.46

OUTPUT VOLTAGE (V)

2.44

LDO

I

OUT2

2.42
243 5678

SUPPLY VOLTAGE (V)

POSITIVE LINEAR REGULATOR

POWER-SUPPLY REJECTION RATIO

= 2N3905)

80

70

MAX1964/65 toc13

I

= 1mA

OUT2

= 100mA

60

50

40

PSRR (dB)

30

20

I

= 50mA

OUT2

10

0

0.1 10 10011000

= 2N3905)

(Q

LDO

FREQUENCY (kHz)

100mA

MAX1964/65 toc14

2.467V

2.457V

POSITIVE LINEAR REGULATOR

LOAD TRANSIENT

= 2N3905)

(Q

LDO

0

10µs/div

A. I

= 1mA TO 100mA, 50mA/div

OUTZ

= 2.5V, 5mV/div

B. V

OUTZ

= 10µF CERAMIC, V

C

LDO(POS)

CIRCUIT OF FIGURE 1

SUP(POS)

MAX1964/65 toc15

= 3.3V

A

B

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple
Power-Supply Controllers

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, V

OUT

= 3.3V, TA= +25°C, unless otherwise noted.)

2.50

0.01 0.1 1000100

POSITIVE LINEAR REGUALTOR

OUTPUT VOLTAGE vs. LOAD CURRENT

(Q

LDO

= TIP30)

2.42

2.44

2.46

2.48

MAX1964/65 toc16

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

110

V

SUP(POS)

= 5.0V

V

SUP(POS)

= 3.3V

2.42

2.44

2.46

2.48

2.50

2 4 6 8 10 12

POSITIVE LINEAR REGULATOR

OUTPUT VOLTAGE vs. SUPPLY VOLTAGE

(Q

LDO

= TIP30)

MAX1964/65 toc17

SUPPLY VOLTAGE (V)

OUTPUT VOLTAGE (V)

I

OUT2

= 1mA

I

OUT2

= 100mA

80

70

60

50

40

30

20

10

0

0.1 10 1001 1000

POSITIVE LINEAR REGULATOR

POWER-SUPPLY REJECTION RATIO

(Q

LDO

= TIP30)

MAX1964/65 toc18

FREQUENCY (kHz)

PSRR (dB)

I

OUT2

= 150mA

POSITIVE LINEAR REGULATOR

LOAD TRANSIENT

(Q

LDO

= TIP30)

MAX1964/65 toc19

250mA

2.453V

2.473V

A. I

OUT2

= 10mA TO 250mA, 200mA/div

B. V

OUT2

= 2.5V, 10mV/div

C

LDO(POS)

= 10µF CERAMIC, V

SUP(POS)

= 3.3V

CIRCUIT OF FIGURE 1

0

B

A

10µs

0

10

5

25

20

15

40

35

30

45

0426810

NEGATIVE LINEAR REGULATOR BASE-

DRIVE CURRENT vs. BASE-DRIVE VOLTAGE

MAX1964/65 toc20

V

OUT

- VB5 (V)

BASE-DRIVE SOURCE CURRENT (mA)

V

FB5

= 250mV

V

FB5

= 50mV

V

OUT

= 5.0V

V

OUT

= 3.3V

B5 (MAX1965) ONLY

-12.00

-12.06

-12.12

-12.18

-12.24

0.01 1

10

1000.1 1000

NEGATIVE LINEAR REGULATOR

OUTPUT VOLTAGE vs. LOAD CURRENT

(Q

LDO

= TIP29)

MAX1964/65 toc21

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

V

SUP(NEG)

= -15V

V

OUT3

= 5V

MAX1964/MAX1965

Tracking/Sequencing Triple/Quintuple

Power-Supply Controllers

_______________________________________________________________________________________ 9

Pin Description

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, V

OUT

- 3.3V, TA= +25°C, unless otherwise noted.)

PIN

MAX1964 MAX1965

1 1 POK

2 2 COMP

3 3 OUT

NEGATIVE LINEAR REGULATOR

OUTPUT VOLTAGE vs. SUPPLY VOLTAGE

-12.00

-12.06

-12.12

OUTPUT VOLTAGE (V)

-12.18

-12.24

-20 -18 -16 -14 -12 -10

NAME FUNCTION

Open-Drain Power-Good Output. POK is low when any output voltage is more than
10% below its regulation point. POK is high impedance when all the outputs are in
regulation. Connect a resistor between POK and VL for logic-level voltages.

Compensation Pin. Connect the compensation network to GND to compensate the
control loop.

Regulated Output Voltage High-Impedance Sense Input. Internally connected to a
resistive-divider and negative gain block (MAX1965).

= TIP29)

(Q

LDO

I

= 100mA

LDO(NEG)

I

= 1mA

LDO(NEG)

SUPPLY VOLTAGE (V)

MAX1964/65 toc22

Dual-Mode Switching-Regulator Feedback Input. Connect to GND for the preset 3.3V

44FB

55B2

6 6 FB2

output. Connect to a resistive-divider from the output to FB to GND to adjust the output
voltage between 1.236V and 0.75

Open-Drain Output PNP Transistor Driver (Regulator 2). Internally connected to the
drain of a DMOS. B2 connects to the base of an external PNP pass transistor to form a
positive linear regulator.

Analog Gain Block Feedback Input (Regulator 2). Connect to a resistive-divider
between the positive linear regulator’s output and GND to adjust the output voltage.
The feedback set point is 1.24V.

✕ V

. The feedback set point is 1.236V.

IN