19-0438; Rev 0; 9/95
UAL
IT MAN
TION K
A
EET
EVALU
ATA SH
OWS D
FOLL
5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller
____________________________Features
o
1.8V to 16.5V Input Range
o
85% Efficiency for 30mA to 1.5A Load Currents
o
Up to 10W Output Power
o
110µA Max Supply Current
o
5µA Max Shutdown Current
o
Preset 5V or Adjustable Output (3V to 16.5V)
o
Current-Limited PFM Control Scheme
o
Up to 300kHz Switching Frequency
o
Evaluation Kit Available
_______________General Description
The MAX608 low-voltage step-up controller operates
from a 1.8V to 16.5V input voltage range. Pulse-fre-
quency-modulation (PFM) control provides high effi-
ciency at heavy loads, while using only 85µA (typical)
when operating with no load. In addition, a logic-con-
trolled shutdown mode reduces supply current to 2µA
typical. The output voltage is factory-set at 5V or can be
adjusted from 3V to 16.5V with an external resistor
divider.
The MAX608 is ideal for two- and three-cell battery-
powered systems. An operating frequency of up to
300kHz allows use with small surface-mount compo-
nents.
The MAX608 operates in “bootstrapped” mode only
(with the chip supply, OUT, connected to the DC-DC
output). For a 12V output without external resistors, or
for nonbootstrapped applications (chip supply connect-
ed to input voltage), refer to the pin-compatible
MAX1771. The MAX608 is available in 8-pin DIP and
SO packages.
MAX608
________________________Applications
High-Efficiency DC-DC Converters
Battery-Powered Applications
Positive LCD-Bias Generators
Portable Communicators
______________Ordering Information
PART
MAX608C/D
MAX608EPA
MAX608ESA
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
Dice*
8 Plastic DIP
8 SO
* Contact factory for dice specifications.
__________Typical Operating Circuit
INPUT
1.8V TO V
OUT
OUTPUT
5V
EXT
CS
N
__________________Pin Configuration
TOP VIEW
ON/OFF
MAX608
SHDN
REF
EXT
OUT
1
2
8
CS
GND
AGND
REF
MAX608
7
6
5
FB
3
SHDN
4
FB AGND GND OUT
DIP/SO
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller
MAX608
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
OUT to GND.............................................................-0.3V, 17V
EXT, CS, REF, SHDN, FB to GND ...............-0.3V, (V
OUT
+ 0.3V)
GND to AGND.............................................................0.1V, -0.1V
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
SO (derate 5.88mW/°C above +70°C) .........................471mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
OUT
= 5V, I
LOAD
= 0mA, T
A
= -40°C to +85°C where indicated. T
A
= -25°C to +85°C for all other limits. Typical values are at
T
A
= +25°C.)
PARAMETER
Input Voltage Range
(Note 2)
Minimum Start-Up Voltage
SYMBOL
CONDITIONS
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
No load
V
OUT
= 16.5V,
SHDN
≤
0.4V
V
OUT
= 10V,
SHDN
≥
1.6V
Output Voltage (Note 3)
Output Voltage Line
Regulation (Note 4)
Output Voltage Load
Regulation (Note 4)
Maximum Switch On-Time t
ON
(max)
Minimum Switch Off-Time
Efficiency
Reference Voltage
REF Load Regulation
REF Line Regulation
FB Trip Point Voltage
(Note 5)
FB Input Current
SHDN Input High Voltage
SHDN Input Low Voltage
SHDN Input Current
2
V
FB
I
FB
V
IH
V
IL
I
IN
V
REF
t
OFF
(min)
V
IN
= 4V, V
OUT
= 5V, I
LOAD
= 500mA,
circuit of Figure 2a
I
REF =
0µA
0µA
≤
I
REF
≤
100µA
3V
≤
V
OUT
≤
16.5V
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
V
OUT
= 1.8V to 16.5V
V
OUT
= 1.8V to 16.5V
V
OUT
= 16.5V, SHDN = 0V or 16.5V
1.6
0.4
±1
1.4625
1.4475
-4
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
1.4625
1.4475
-4
40
1.5
V
IN
= 2.0V to 5.0V,
over full load range,
circuit of Figure 2a
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
4.825
4.800
5.0
5.0
7
60
12
1.8
16
2.3
87
1.5
1.5375
1.5525
10
100
1.5375
1.5525
±20
±40
20
2.8
2
MIN
1.8
1.9
1.6
85
TYP
MAX
16.5
16.5
1.8
110
120
5
10
5.175
V
5.200
mV/V
mV/A
µs
µs
%
V
mV
µV/V
V
nA
UNITS
V
V
µA
µA
Supply Current
V
IN
= 2.7V to 4.0V, V
OUT
= 5V, I
LOAD
= 500mA,
circuit of Figure 2a
V
IN
= 2V, V
OUT
= 5V, I
LOAD
= 0mA to 500mA,
circuit of Figure 2a
V
V
µ
A
_______________________________________________________________________________________
5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller
ELECTRICAL CHARACTERISTICS (continued)
(V
OUT
= 5V, I
LOAD
= 0mA, T
A
= -40°C to +85°C where indicated. T
A
= -25°C to +85°C for all other limits. Typical values are at
T
A
= +25°C.)
PARAMETER
Current-Limit Trip Level
CS Input Current
EXT Rise Time
EXT Fall Time
EXT On-Resistance
SYMBOL
V
CS
I
CS
V
OUT
= 5V, 1nF from EXT to GND
V
OUT
= 5V, 1nF from EXT to GND
EXT = high or low
CONDITIONS
V
OUT
= 3V to 16.5V
T
A
= -25°C to +85°C
T
A
= -40°C to +85°C (Note 1)
MIN
85
80
0.01
50
50
15
30
TYP
100
MAX
115
120
±1
UNITS
mV
µA
ns
Ω
MAX608
Note 1:
Limits over this temperature range are guaranteed by design.
Note 2:
The MAX608 must be operated in bootstrapped mode with OUT connected to the DC-DC circuit output. The minimum output
voltage set point is +3V.
Note 3:
Output voltage guaranteed using preset voltages. See Figures 4a–4d for output current capability versus input voltage.
Note 4:
Output voltage line and load regulation depend on external circuit components.
Note 5:
Operation in the external-feedback mode is guaranteed to be accurate to the V
FB
trip level, and does not include resistor tolerance.
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 5V)
MAX608-01
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 12V)
MAX608-02
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 3.3V)
MAX608-03
100
V
IN
= 4.0V
90
EFFICIENCY (%)
V
IN
= 3.5V
100
V
IN
= 9.0V
90
EFFICIENCY (%)
V
IN
= 6.0V
V
IN
= 5.0V
100
90
EFFICIENCY (%)
V
IN
= 3.0V
80
V
IN
= 3.0V
70
V
IN
= 2.0V
80
V
IN
= 3.0V
V
IN
= 2.0V
80
70
70
V
IN
= 2.0V
60
1
10
100
1000
LOAD CURRENT (mA)
60
1
10
100
1000
LOAD CURRENT (mA)
60
1
10
100
1000
LOAD CURRENT (mA)
LOAD CURRENT vs.
MINIMUM START-UP
INPUT VOLTAGE
MAX608-04
LOAD CURRENT vs.
MINIMUM START-UP
INPUT VOLTAGE
V
OUT
= 12V
CIRCUIT OF FIGURE 2b
EXTERNAL FET THRESHOLD LIMITS
FULL-LOAD START-UP BELOW 3.6V
MAX608-05
SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX608-06
700
600
LOAD CURRENT (mA)
500
400
300
200
100
0
1.8
2.2
2.6
3.0
3.4
3.8
V
OUT
= 5V
CIRCUIT OF FIGURE 2a
EXTERNAL FET THRESHOLD LIMITS
FULL-LOAD START-UP BELOW 3.7V
500
200
SUPPLY CURRENT (µA)
400
LOAD CURRENT (mA)
150
300
100
200
50
100
0
4.0
1.8
2.2
2.6
3.0
3.4
3.8
4.0
MINIMUM START-UP VOLTAGE (V)
MINIMUM START-UP VOLTAGE (V)
0
0
1
2
3
4
5
INPUT VOLTAGE (V)
_______________________________________________________________________________________
3
5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller
MAX608
____________________________Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
EXT RISE/FALL TIME vs. SUPPLY VOLTAGE
MAX608-07
REFERENCE OUTPUT RESISTANCE vs.
TEMPERATURE
REFERENCE OUTPUT RESISTANCE (Ω)
MAX608-08
REFERENCE vs. TEMPERATURE
MAX608-09
250
200
250
1.506
1.504
1.502
REFERENCE (V)
1.500
1.498
1.496
1.494
EXT RISE/FALL TIME (ns)
C
EXT
= 2200pF
C
EXT
= 1000pF
C
EXT
= 470pF
C
EXT
= 100pF
200
10µA
150
150
100
100
50µA
100µA
50
50
0
2
4
6
8
10
12
SUPPLY VOLTAGE (V)
0
-60 -40 -20
0 20 40 60 80 100 120 140
TEMPERATURE (°C)
1.492
-60 -40 -20
0 20 40 60 80 100 120 140
TEMPERATURE (°C)
MAXIMUM SWITCH ON-TIME vs.
TEMPERATURE
MAX608-10
SHUTDOWN CURRENT vs. TEMPERATURE
3.5
SHUTDOWN CURRENT (µA)
3.0
2.5
2.0
1.5
V+ = 8V
1.0
0.5
V+ = 4V
2.20
-60 -40 -20
0 20 40 60 80 100 120 140
TEMPERATURE (°C)
V+ = 15V
tOFF(min) (µs)
MAX608-11
MINIMUM SWITCH OFF-TIME vs.
TEMPERATURE
MAX608-12
16.5
4.0
2.30
tON(max) (µs)
16.0
2.25
15.5
-60 -30
0
30
60
90
120 150
TEMPERATURE (°C)
0
-60 -30
0
30
60
90
120 150
TEMPERATURE (°C)
HEAVY-LOAD SWITCHING WAVEFORMS
(V
OUT
= 5V)
A
B
V
OUT
A
0V
I
LIM
B
0A
C
C
MEDIUM-LOAD SWITCHING WAVEFORMS
(V
OUT
= 5V)
V
OUT
0V
I
LIM
0A
2µs/div
V
IN
= 3V, I
OUT
= 930mA, V
OUT
= 5V
A = EXT VOLTAGE, 5V/div
B = INDUCTOR CURRENT, 1A/div
C = V
OUT
RIPPLE, 50mV/div, AC-COUPLED
20µs/div
V
IN
= 3V, I
OUT
= 490mA, V
OUT
= 5V
A = EXT VOLTAGE, 5V/div
B = INDUCTOR CURRENT, 1A/div
C = V
OUT
RIPPLE, 50mV/div, AC-COUPLED
4
_______________________________________________________________________________________
5V or Adjustable, Low-Voltage,
Step-Up DC-DC Controller
____________________________Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
HEAVY-LOAD SWITCHING WAVEFORMS
(V
OUT
= 12V)
V
OUT
A
0V
I
LIM
B
0A
C
C
B
0A
A
MAX608
MEDIUM-LOAD SWITCHING WAVEFORMS
(V
OUT
= 12V)
V
OUT
0V
I
LIM
2µs/div
V
IN
= 4V, I
OUT
= 490mA, V
OUT
= 12V
A = EXT VOLTAGE, 10V/div
B = INDUCTOR CURRENT, 1A/div
C = V
OUT
RIPPLE, 50mV/div, AC-COUPLED
10µs/div
V
IN
= 4V, I
OUT
= 300mA, V
OUT
= 12V
A = EXT VOLTAGE, 10V/div
B = INDUCTOR CURRENT, 1A/div
C = V
OUT
RIPPLE, 50mV/div, AC-COUPLED
LINE-TRANSIENT RESPONSE
(V
OUT
= 5V)
LOAD-TRANSIENT RESPONSE
(V
OUT
= 5V)
A
4.0V
2.7V
500mA
A
0A
B
B
5ms/div
I
OUT
= 500mA, V
OUT
= 5V
A = V
IN
, 2.7V TO 4.0V, 1V/div
B = V
OUT
RIPPLE, 100mV/div, AC-COUPLED
2ms/div
V
IN
= 2V, V
OUT
= 5V
A = LOAD CURRENT, 0mA TO 500mA, 500mA/div
B = V
OUT
RIPPLE, 50mV/div, AC-COUPLED
EXITING SHUTDOWN
A
0V
5V
B
0V
200µs/div
I
OUT
= 500mA, V
IN
= 3.5V
A = SHDN, 2V/div
B = V
OUT
, 2V/div
_______________________________________________________________________________________
5
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