19-0225; Rev 3; 9/97
KIT
ATION
EVALU
BLE
AVAILA
5V/3.3V/3V or Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Controllers
_______________General Description
The MAX649/MAX651/MAX652 BiCMOS, step-down DC-
DC switching controllers provide high efficiency over
three decades of load current. A unique, current-limited
pulse-frequency-modulated (PFM) control scheme gives
these devices the benefits of pulse-width-modulation
(PWM) converters (high efficiency at heavy loads), while
using only 100µA of supply current (vs. 2mA to 10mA for
PWM converters). The result is high efficiency over loads
ranging from 10mA to more than 2.5A.
These devices use miniature external components.
Their high switching frequency (up to 300kHz) allows
for less than 9mm diameter surface-mount inductors.
The MAX649/MAX651/MAX652 have dropout voltages
less than 1V and accept input voltages up to 16.5V.
Output voltages are preset at 5V (MAX649), 3.3V
(MAX651), and 3V (MAX652). These controllers can
also be adjusted to any voltage from 1.5V to the input
voltage by using two resistors.
These step-down controllers drive external P-channel
MOSFETs at loads greater than 10W. If less power is
required, use the MAX639/MAX640/MAX653 step-down
converters with on-chip FETs, which allow up to a
225mA load current.
____________________________Features
o
More than 90% Efficiency (10mA to 1.5A Loads)
o
More than 12.5W Output Power
o
100µA Max Quiescent Supply Current
o
5µA Max Shutdown Supply Current
o
Less than 1.0V Dropout Voltage
o
16.5V Max Input Voltage
o
5V (MAX649), 3.3V (MAX651), 3V (MAX652),
or Adjustable Output Voltage
o
Current-Limited Control Scheme
o
Up to 300kHz Switching Frequency
MAX649/MAX651/MAX652
______________Ordering Information
PART
MAX649CPA
MAX649CSA
MAX649C/D
MAX649EPA
MAX649ESA
MAX649MJA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
________________________Applications
5V-to-3.3V Green PC Applications
High-Efficiency Step-Down Regulation
Minimum-Component DC-DC Converters
Battery-Powered Applications
Ordering Information continued at end of data sheet.
* Dice are tested at T
A
= +25°C.
**Contact factory for availability and processing to MIL-STD-883.
__________Typical Operating Circuit
INPUT
4V TO 16.5V
__________________Pin Configuration
TOP VIEW
V+
OUT
1
2
8
7
GND
EXT
CS
V+
MAX651
ON/OFF
SHDN
CS
EXT
P
OUTPUT
3.3V
FB
SHDN
3
REF
4
MAX649
MAX651
MAX652
6
5
REF
FB
GND
OUT
DIP/SO
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
5V/3.3V/3V or Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Controllers
MAX649/MAX651/MAX652
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V+ to GND.......................................-0.3V, +17V
REF, SHDN, FB, CS, EXT, OUT .......................-0.3V, (V+ + 0.3V)
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
CERDIP (derate 8.00mW/°C above +70°C) ..................640mW
Operating Temperature Ranges
MAX649C_A, MAX65_C_A ..................................0°C to +70°C
MAX649E_A, MAX65_E_A ................................-40°C to +85°C
MAX649MJA, MAX65_MJA ............................-55°C to +125°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+ = 5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
V+ Input Voltage Range
Supply Current
SYMBOL
V+
V+ = 16.5V, SHDN
≤
0.4V (operating, switch off)
I
Q
V+ = 16.5V, SHDN
≥
1.6V (shutdown)
V+ = 10V, SHDN
≥
1.6V (shutdown)
MAX649C, MAX65_C
FB Trip Point
MAX649E, MAX65_E
MAX649M, MAX65_M
MAX649C, MAX65_C
FB Input Current
I
FB
MAX649E, MAX65_E
MAX649M, MAX65_M
MAX649, V+ = 6V to 16.5V
Output Voltage
V
OUT
Circuit of
Figure 1
MAX651, V+ = 4V to 16.5V
MAX652, V+ = 4V to 16.5V
MAX649C, MAX65_C, I
REF
= 0
Reference Voltage
V
REF
MAX649E, MAX65_E, I
REF
= 0
MAX649M, MAX65_M, I
REF
= 0
REF Load Regulation
REF Line Regulation
0
≤
I
REF
≤
100µA,
sourcing only
4V
≤
V+
≤
16.5V
MAX649, 6V
≤
V+
≤
16V,
I
LOAD
= 1A
Output Voltage
Line Regulation
Circuit of
Figure 1
MAX651, 4.5V
≤
V+
≤
16V,
I
LOAD
= 1A
MAX652, 4V
≤
V+
≤
16V,
I
LOAD
= 1A
MAX649C/E, MAX65_C/E
MAX649M, MAX65_M
4.80
3.17
2.88
1.470
1.4625
1.455
5.0
3.3
3.0
1.5
1.5
1.5
4
4
40
2.6
1.7
1.9
mV/V
1.470
1.4625
1.455
CONDITIONS
MIN
4.0
80
4
2
1.5
1.5
1.5
5
1.530
1.5375
1.545
±50
±70
±90
5.20
3.43
3.12
1.530
1.5375
1.545
10
15
100
mV
µV/V
V
V
nA
V
TYP
MAX
16.5
100
µA
UNITS
V
2
_______________________________________________________________________________________
5V/3.3V/3V or Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Controllers
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MAX649, 0
≤
I
LOAD
≤
1.5A,
V
IN
= 10V
Output Voltage
Load Regulation
Circuit of
Figure 1
MAX651, 0
≤
I
LOAD
≤
1.5A,
V
IN
= 5V
MAX652, 0
≤
I
LOAD
≤
1.5A,
V
IN
= 5V
MAX649, V+ = 10V,
I
LOAD
= 1A
Efficiency
Circuit of
Figure 1
MAX651, V+ = 5V,
I
LOAD
= 1A
MAX652, V+ = 5V,
I
LOAD
= 1A
SHDN Input Current
SHDN Input Voltage High
SHDN Input Voltage Low
Current-Limit Trip
Level (V+ to CS)
CS Input Current
Switch Maximum
On-Time
Switch Minimum
Off-Time
EXT Rise Time
EXT Fall Time
t
ON
(max)
t
OFF
(min)
V
IH
V
IL
V
CS
V+ = 16.5V, SHDN = 0V or V+
4V
≤
V+
≤
16.5V
4V
≤
V+
≤
16.5V
4V
≤
V+
≤
16.5V
4V
≤
V+
≤
16.5V
V+ = 12V
V+ = 12V
C
EXT
= 0.001µF, V+ = 12V
C
EXT
= 0.001µF, V+ = 12V
12
1.8
16
2.3
50
50
MAX649C/E, MAX65_C/E
MAX649M, MAX65_M
180
160
210
210
1.6
0.4
240
260
±1
20
2.8
MIN
TYP
-47
-45
MAX
UNITS
MAX649/MAX651/MAX652
mV/A
-45
92
89
%
88
1
µA
V
V
mV
µA
µs
µs
ns
ns
_______________________________________________________________________________________
3
5V/3.3V/3V or Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Controllers
MAX649/MAX651/MAX652
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX649-A01
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX649-A02
MAX649 MAXIMUM LOAD CURRENT
vs. SUPPLY VOLTAGE
MAXIMUM LOAD CURRENT (mA)
MAX649-A03
80
78
76
I+ (mA)
V+ = 10V
V+ = 16.5V
4.0
3.5
3.0
V+ = 16.5V
2.5
I+ (mA)
2.0
1.5
V+ = 8V
2500
2000
74
72
70
1500
1000
V
OUT
= 5V
CIRCUIT OF FIGURE 1
V+ = 4V
68
66
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
1.0
0.5
V+ = 4V
0
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
500
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 1415
INPUT VOLTAGE (V)
MAX649
EFFICIENCY vs. LOAD CURRENT
MAX649-A04
MAX651
EFFICIENCY vs. LOAD CURRENT
MAX649-A05
MAX652
EFFICIENCY vs. LOAD CURRENT
90
80
TOP TO BOTTOM:
V
IN
= 4.3V
V
IN
= 5V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V
MAX649-A06
100
90
80
EFFICIENCY (%)
TOP TO BOTTOM:
V
IN
= 6V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V
100
90
80
EFFICIENCY (%)
TOP TO BOTTOM:
V
IN
= 4.3V
V
IN
= 5V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V
100
60
50
40
30
20
10
0
100µ
1m
10m
V
OUT
= 5V
EFFICIENCY (%)
70
70
60
50
40
30
20
10
V
OUT
= 3.3V
100µ
1m
10m
70
60
50
40
30
20
10
0
V
OUT
= 3V
100µ
1m
10m
100m
1
0
100m
1
LOAD CURRENT (A)
100m
1
LOAD CURRENT (A)
LOAD CURRENT (A)
SWITCH ON-TIME
vs. TEMPERATURE
MAX649-A07
SWITCH OFF-TIME
vs. TEMPERATURE
MAX649-A08
SWITCH ON-TIME/OFF-TIME RATIO
vs. TEMPERATURE
V+ = 5V
7.8
7.6
7.4
t
ON
/t
OFF
RATIO
MAX649-A9
17
V+ = 5V
2.5
V+ = 5V
8.0
16
t
OFF
(ms)
t
ON
(ms)
7.2
7.0
6.8
6.6
6.4
6.2
2.0
15
-60 -40 -20
0
20
40
60
80 100 120
TEMPERATURE (°C)
1.5
-60 -40 -20 0 20 40 60
TEMPERATURE (°C)
80 100 120
6.0
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
4
_______________________________________________________________________________________
5V/3.3V/3V or Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Controllers
____________________________Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
EXT RISE AND FALL TIMES
vs. TEMPERATURE (1nF)
MAX649-A10
MAX649/MAX651/MAX652
EXT RISE AND FALL TIMES
vs. TEMPERATURE (5nF)
MAX649-A11
DROPOUT VOLTAGE
vs. LOAD CURRENT
900
DROPOUT VOLTAGE (mV)
800
700
600
500
400
300
200
MAX651, V
OUT
= 3.3V
MAX649, V
OUT
= 5V
MAX652, V
OUT
= 3V
MAX649-A12
130
120
110
100
t
RISE
& t
FALL
(ns)
90
80
70
60
50
40
30
20
-60 -40 -20 0
V+ = 12V, t
FALL
V+ = 12V, t
RISE
V+ = 5V, t
FALL
C
EXT
= 1nF
V+ = 5V, t
RISE
500
450
400
t
RISE
& t
FALL
(ns)
350
300
250
200
150
100
50
-60 -40 -20 0
V+ = 12V, t
FALL
V+ = 5V, t
FALL
V+ = 12V, t
RISE
C
EXT
= 5nF
V+ = 5V, t
RISE
1000
100
0
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 1.6
20 40 60 80 100 120 140
20 40 60 80 100 120 140
TEMPERATURE (°C)
TEMPERATURE (°C)
LOAD CURRENT (A)
DROPOUT VOLTAGE
vs. TEMPERATURE
MAX649-A13
CS TRIP LEVEL
vs. TEMPERATURE
230
225
REFRENCE OUTPUT (V)
CS TRIP LEVEL (mV)
220
215
210
205
200
195
1.502
1.500
1.498
1.496
1.494
1.492
-60 -40 -20 0
20 40 60 80 100 120 140
MAX649-A14
REFERENCE OUTPUT VOLTAGE
vs. TEMPERATURE
MAX649-A15
1100
MAX649
235
1.506
1.504
DROPOUT VOLTAGE (mV)
1000
900
MAX652
MAX651
800
700
I
LOAD
= 1A
CIRCUIT OF FIGURE 1
600
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
190
185
TEMPERATURE (°C)
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
REFERENCE OUTPUT RESISTANCE
vs. TEMPERATURE
REFRENCE OUTPUT RESISTANCE (Ω)
MAX649-A16
250
200
I
REF
= 10µA
150
I
REF
= 50µA
100
50
I
REF
= 100µA
0
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
_______________________________________________________________________________________
5
PCB Design
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