Maxim MAX1627ESA, MAX1627C-D, MAX1626ESA, MAX1626C-D Datasheet

19-1075; Rev 0; 6/96

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

5V/3.3V or Adjustable, 100% Duty-Cycle,

High-Efficiency, Step-Down DC-DC Controllers

_______________General Description

The MAX1626/MAX1627 step-down DC-DC switching
controllers provide high efficiency over loads ranging
from 1mA to more than 2A. A unique current-limited,
pulse-frequency-modulated (PFM) control scheme
operates with up to a 100% duty cycle, resulting in very
low dropout voltages. This control scheme eliminates
minimum load requirements and reduces the supply
current under light loads to 90µA (versus 2mA to 10mA
for common pulse-width modulation controllers).

These step-down controllers drive an external P-chan­nel MOSFET, allowing design flexibility for applications
to 12W or higher. Soft-start reduces current surges dur­ing start-up. A high switching frequency (up to 300kHz)
and operation in continuous-conduction mode allow the
use of tiny surface-mount inductors. Output capacitor
requirements are also reduced, minimizing PC board
area and system costs.

The output voltage is preset at 5V or 3.3V for the
MAX1626 and adjustable for the MAX1627. Input volt­ages can be up to 16.5V. The MAX1626/MAX1627 are
functional upgrades for the MAX1649/MAX1651.

________________________Applications

PCMCIA Power Supplies
Personal Digital Assistants
Hand-Held Computers
Portable Terminals
Low-Cost Notebook Computer Supplies
5V to 3.3V Green PC Applications
High-Efficiency Step-Down Regulation
Minimum-Component DC-DC Converters
Battery-Powered Applications

__________________Pin Configuration

TOP VIEW

OUT

3/5 (FB)

( ) ARE FOR MAX1627

SHDN

REF

1
2
3
4

MAX1626
MAX1627

SO

8

GND
EXT

7

CS

6
5

V+



____________________________Features

♦ Low Dropout Voltage
♦ 100% Maximum Duty Cycle
♦ Soft-Start Limits Start-Up Current
♦ Efficiency >90% (3mA to 2A Loads)
♦ Output Power >12.5W
♦ 90µA Max Quiescent Current
♦ 1µA Max Shutdown Current
♦ Up to 300kHz Switching Frequency
♦ 16.5V Max Input Voltage
♦ Output Voltage: 5V/3.3V (MAX1626)

Adjustable (MAX1627)

♦ Current-Limited Control Scheme

______________Ordering Information

PART

MAX1626C/D

MAX1626ESA
MAX1627C/D
MAX1627ESA -40°C to +85°C 8 SO

* Dice are tested at TA= +25°C.

TEMP. RANGE PIN-PACKAGE

0°C to +70°C

-40°C to +85°C
0°C to +70°C

Dice*
8 SO
Dice*

__________Typical Operating Circuit

INPUT

3.3V to 16.5V

V+

MAX1626

GND

EXT

OUT

CSSHDN

P

ON/OFF

3/5

REF

OUTPUT

3.3V

MAX1626/MAX1627

________________________________________________________________

Maxim Integrated Products

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

5V/3.3V or Adjustable, 100% Duty-Cycle,
High-Efficiency, Step-Down DC-DC Controllers

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, V+ to GND.......................................-0.3V, +17V

OUT, FB, 3/5, SHDN, REF, CS, EXT to GND...-0.3V, (V+ + 0.3V)
Maximum Current at REF (I
Maximum Current at EXT (I
Continuous Power Dissipation (T

SO (derate 5.88mW/°C above +70°C)..........................471mW

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.

)..........................................15mA

REF

) ..........................................50mA

EXT

= +70°C)

A

ELECTRICAL CHARACTERISTICS

(V+ = +3V to +16.5V, SHDN = 3/5 = 0V, TA= 0°C to +85°C, unless otherwise noted.)

Operating, no load

V

I+Supply Current into V+

V+ = SHDN = 16.5V (shutdown)

Circuit of Figure 1, 3/5 = V+ (Note 1)

OUT

Circuit of Figure 1, 3/5 = 0V (Note 1)
MAX1626, 3/5 = V+, output forced to 5V

OUT

MAX1627, includes hysteresis
MAX1627

CS

SHDN = 0V or V+

3/5 = 0V or V+
V+ = 5V
Output forced to 0V
Output in regulation

6.0V < V+ < 12.0V, I
30mA < I

LOAD

I

= 0µA

LOAD

REF

REF

≤ 100µA

0µA ≤ I
V+ = 3V to 16.5V, I

MAX1626/MAX1627

Output Voltage
OUT Input Current

CS Threshold Voltage

3/5 Input Voltage High
3/5 Input Voltage Low
3/5 Leakage Current

Minimum EXT Off Time

Reference Voltage

Operating Temperature Range

MAX1626ESA/MAX1627ESA............................-40°C to +85°C

Storage Temperature Range.............................-65°C to +160°C

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

CONDITIONS

70 90

4.85 5.00 5.15

3.20 3.30 3.40

81012

1.5 2.0 2.5

= 1A

LOAD

< 2.0A, V+ = 8V

= 0µA µV/V10 100REF Line Regulation

LOAD

UNITSMIN TYP MAXSYMBOLPARAMETER

1

V3.0 16.5V+Input Voltage Range

µA

V2.7 2.8Undervoltage Lockout
V

µA24 37 50I

V1.27 1.30 1.33FB Threshold Voltage
nA035FB Leakage Current
µA010CS Input Current

mV85 100 115V

V1.6SHDN Input Voltage High

V0.4SHDN Input Voltage Low
µA±1SHDN Input Current

VV+ - 0.5

V0.5
µA±1

Ω10EXT Resistance
µs

%100EXT Duty-Cycle Limit
mV/V5Line Regulation
mV/A15Load Regulation

V1.27 1.30 1.33V

mV410REF Load Regulation

2 _______________________________________________________________________________________

5V/3.3V or Adjustable, 100% Duty-Cycle,

High-Efficiency, Step-Down DC-DC Controllers

ELECTRICAL CHARACTERISTICS

(V+ = +3V to +16.5V, SHDN = 3/5 = 0V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)

CONDITIONS

Operating, no load

Supply Current into V+

Output Voltage
OUT Input Current

I

V

OUT

V+ = SHDN = 16.5V (shutdown)

Circuit of Figure 1, 3/5 = V+

OUT

Circuit of Figure 1, 3/5 = 0V
MAX1626, 3/5 = V+, output forced to 5V

OUT

MAX1627, includes hysteresis
MAX1627

I

= 0µA

LOAD

Note 1: V+ must exceed V
Note 2: Specifications from 0°C to -40°C are guaranteed by design, not production tested.

to maintain regulation.

OUT

4.80 5.20

3.16 3.44

100

2

MAX1626/MAX1627

UNITSMIN TYP MAXSYMBOLPARAMETER

V3.0 16.5V+Input Voltage

µA

V2.9Undervoltage Lockout
V

µA24 50I

V1.25 1.35FB Threshold Voltage

nA050FB Leakage Current

mV80 120CS Threshold Voltage

V1.25 1.35Reference

__________________________________________Typical Operating Characteristics

(Circuit of Figure 1, TA= +25°C, unless otherwise noted.)

DROPOUT VOLTAGE

0.45

0.40

0.35

0.30

0.25

0.20

0.15

DROPOUT VOLTAGE (V)

0.10

0.05
0

vs. LOAD CURRENT

3.3V SETTING
= +3.17V

V

OUT

0 0.5 1.0 1.5 2.0 2.5

LOAD (A)

_______________________________________________________________________________________ 3

5V SETTING

= +4.8V

V

OUT

MAX1626-11

EFFICIENCY vs. LOAD CURRENT

(V

= +3.3V)

100

90

A

80
70
60
50
40

EFFICIENCY (%)

30
20
10

CIRCUIT OF FIGURE 1

0

0.1m 100m 11m 10m 10

C

B

LOAD CURRENT (A)

OUT

D E F

A: V+ = +4.3V
B: V+ = +5V
C: V+ = +8V
D: V+ = +10V
E: V+ = +12V
F: V+ = +15V


MAX1626-05

EFFICIENCY (%)

EFFICIENCY vs. LOAD CURRENT

(V

= +5V)

100

90

A
80
70

60
50
40
30
20
10

CIRCUIT OF FIGURE 1

0

0.1m 100m 11m 10m 10

OUT

C

B

LOAD CURRENT (A)

D

E

A: V+ = +6V
B: V+ = +8V
C: V+ = +10V
D: V+ = +12V
E: V+ = +15V


MAX1626-03

5V/3.3V or Adjustable, 100% Duty-Cycle,
High-Efficiency, Step-Down DC-DC Controllers

____________________________Typical Operating Characteristics (continued)

(Circuit of Figure 1, TA= +25°C, unless otherwise noted.)

MAX1626 SHUTDOWN CURRENT

0.8

0.7

0.6

0.5

0.4

0.3

0.2

SHUTDOWN CURRENT (µA)

0.1
0

-60

MAX1626/MAX1627

vs. TEMPERATURE

APPLICATION CIRCUIT
SHUTDOWN CURRENT:
A: V+ = +15V
B: V+ = +10V
C: V+ = +4V

MAX1626 SHUTDOWN
CURRENT:
D: V+ = +16V
E: V+ = +4V


-20 0 204060 80 100120

-40
TEMPERATURE (°C)

A

MAX1626-04

B

C

D

EXT OFF TIME (µs)

E

140

MAX1626 EXT OFF TIME

vs. OUTPUT VOLTAGE

12

10

8

6

4

2

0

012345

3/5 = V+

3/5 = GND

OUTPUT VOLTAGE (V)

V+ = +5V

MAX1626-02

12

10

8

6

4

EXT OFF TIME (µs)

2

MAX1627 EXT OFF TIME

vs. FB PIN VOLTAGE

0

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

FB PIN VOLTAGE (V)

V+ = +5V

MAX1626-03

EXT RISE AND FALL TIMES

50
45
40
35

(ns)

30

FALL

25

AND t

20

RISE

t

15
10

5
0

-60 -40 -20 40 60 140

vs. TEMPERATURE

t

, V+ = +5V

FALL

t

RISE

C

= 1nF

EXT

3/5 = 0V
OUT = 50kHz, 0.3Vp-p

0

20 80

TEMPERATURE (°C)

t

RISE

, t

FALL

3.3V

,

, V+ = +5V

, V+ = +15V

DC

100 120

MAX1626-09

400
350
300

(ns)

250

FALL

200

AND t

150

RISE

t

100

50

EXT RISE AND FALL TIMES

vs. CAPACITANCE

t

, V+ = +15V

RISE

, V+ = +5V

t

FALL

t

, V+ = +5V

RISE

, V+ = +15V

t

0

0 2000 4000

CAPACITANCE (pF)

FALL

MAX1626

V+ QUIESCENT CURRENT

72

70

68

66

(µA)

Q

I

64

62

60

-60

vs. TEMPERATURE

V+ = +16V

V+ = +10V

V+ = +4V

3/5 = 0V
OUT FORCED TO 3.4V

-20 0 204060 80 100120

-40
TEMPERATURE (°C)

MAX1626-01

140

CS TRIP LEVEL vs. TEMPERATURE

115

OUT = 0V

110

105

100

95

CS TRIP LEVEL (mV)

90

85

-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)

4 _______________________________________________________________________________________

MAX1626-10

MAX1626-12

5V/3.3V or Adjustable, 100% Duty-Cycle,

High-Efficiency, Step-Down DC-DC Controllers

____________________________Typical Operating Characteristics (continued)

(Circuit of Figure 1, TA= +25°C, unless otherwise noted.)

MAX1626/MAX1627

REFERENCE OUTPUT VOLTAGE

vs. TEMPERATURE

1.310

1.305

1.300

1.295

1.290

1.285

REFERENCE OUTPUT VOLTAGE (V)

1.280

I

= 0µA

REF

= 50µA

I

REF

-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)

MAX1626 LOAD-TRANSIENT RESPONSE

A

I

REF

= 10µA

I

REF

= 100µA

MAX1626-15

MAX1626-13

MAX1626 LINE-TRANSIENT RESPONSE

A

MAX1626 SHUTDOWN RESPONSE TIME

AND SUPPLY CURRENT

A

B

C

V+ = 8V, V
A: OUT, 2V/div
B: SUPPLY CURRENT, 1A/div
C: SHDN, 5V/div

500µs/div

= 5V, LOAD = 1A

OUT

LINE-TRANSIENT RESPONSE

FROM 100% DUTY CYCLE

MAX1626-16

A

MAX1626-14

MAX1626-17

B

V+ = 8V, V
A: OUT, 50mV/div, 3.3V DC OFFSET
B: LOAD CURRENT, 1A/div


100µs/div

= 3.3V, LOAD = 30mA to 2A

OUT

_______________________________________________________________________________________

B

V

= 5V, LOAD = 1A, CIN = 33µF

OUT

A: OUT, 100mV/div, 5V DC OFFSET
B: V+ 6V to 12V, 2V/div

5ms/div

B

V

= 3.3V, LOAD = 1A, CIN = 47µF

OUT

A: OUT, 100mV/div, 3.3V DC OFFSET
B: V+ 3.3V to 15V, 5V/div

5ms/div

5