19-1357; Rev 1; 7/98
KIT
ATION
EVALU
BLE
AVAILA
High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
General Description
____________________________Features
o
96% Efficiency
o
Small, 16-Pin QSOP Package
(half the size of a 16-pin narrow SO)
o
Pin-Compatible with MAX797 (MAX1653/MAX1655)
o
Output Voltage Down to 1V (MAX1655)
o
4.5V to 30V Input Range
o
99% Duty Cycle for Lower Dropout
o
170µA Quiescent Supply Current
o
3µA Logic-Controlled Shutdown
o
Dual, N-Channel, Synchronous-Rectified Control
o
Fixed 150kHz/300kHz PWM Switching,
or Synchronized from 190kHz to 340kHz
o
Programmable Soft Start
o
Low-Cost Secondary Outputs (MAX1652/MAX1654)
MAX1652–MAX1655
The MAX1652–MAX1655 are high-efficiency, pulse-
width-modulated (PWM), step-down DC-DC controllers
in small QSOP packages. The MAX1653/MAX1655 also
come in 16-pin narrow SO packages that are pin-
compatible upgrades to the popular MAX797. Improve-
ments include higher duty-cycle operation for better
dropout, lower quiescent supply currents for better
light-load efficiency, and an output voltage down to 1V
(MAX1655).
The MAX1652–MAX1655 achieve up to 96% efficiency
and deliver up to 10A using a unique Idle Mode™ syn-
chronous-rectified PWM control scheme. These devices
automatically switch between PWM operation at heavy
loads and pulse-frequency-modulated (PFM) operation
at light loads to optimize efficiency over the entire out-
put current range. The MAX1653/MAX1655 also feature
logic-controlled, forced PWM operation for noise-sensi-
tive applications.
All devices operate with a selectable 150kHz/300kHz
switching frequency, which can also be synchronized
to an external clock signal. Both external power switch-
es are inexpensive N-channel MOSFETs, which provide
low resistance while saving space and reducing cost.
The MAX1652 and MAX1654 have an additional feed-
back pin that permits regulation of a low-cost second
output tapped from a transformer winding. The
MAX1652 provides an additional positive output. The
MAX1654 provides an additional negative output.
The MAX1652–MAX1655 have a 4.5V to 30V input volt-
age range. The MAX1652/MAX1653/MAX1654’s output
range is 2.5V to 5.5V while the MAX1655’s output range
extends down to 1V. An evaluation kit (MAX1653EVKIT)
is available to speed designs.
Ordering Information
PART
MAX1652EEE
MAX1653ESE
MAX1653EEE
MAX1654EEE
MAX1655ESE
MAX1655EEE
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 Narrow SO
16 QSOP
16 QSOP
16 Narrow SO
16 QSOP
Applications
Notebook Computers
PDAs
Cellular Phones
Hand-Held Computers
Handy-Terminals
Mobile Communicators
Distributed Power
MAX1654
2.5
MAX1653
2.5
MAX1652
2.5
PART
FEEDBACK
VOLTAGE (V)
Selection Guide
SPECIAL
FEATURE
COMPATIBILITY
Regulates positive Same pin order
secondary voltage as MAX796, but
(such as +12V)
smaller package
Logic-controlled, Pin-compatible
low-noise mode with MAX797
Regulates negative Same pin order
secondary voltage as MAX799, but
(such as -5V)
smaller package
Low output volt-
ages (1V to 5.5V);
logic-controlled,
low-noise mode
Pin compatible
with MAX797
(except for feed-
back voltage)
Pin Configurations appear at end of data sheet.
Idle Mode is a trademark of Maxim Integrated Products.
MAX1655
1
________________________________________________________________
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 408-737-7600 ext. 3468.
High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
MAX1652–MAX1655
ABSOLUTE MAXIMUM RATINGS
V+ to GND ..............................................................-0.3V to +36V
GND to PGND .......................................................-0.3V to +0.3V
VL to GND ................................................................-0.3V to +6V
BST to GND ............................................................-0.3V to +36V
DH to LX .....................................................-0.3V to (BST + 0.3V)
LX to BST..................................................................-6V to +0.3V
SHDN
to GND...............................................-0.3V to (V+ + 0.3V)
SYNC, SS, REF, SECFB,
SKIP,
FB to GND...-0.3V to (VL + 0.3V)
DL to PGND ..................................................-0.3V to (VL + 0.3V)
CSH, CSL to GND ....................................................-0.3V to +6V
VL Short Circuit to GND..............................................Momentary
REF Short Circuit to GND ...........................................Continuous
VL Output Current ...............................................+50mA to -1mA
REF Output Current...............................................+5mA to -1mA
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 8.70mW/°C above +70°C) .......................696mW
QSOP (derate 8.3mW/°C above +70°C) ....................667mW
Operating Temperature Range
MAX165_E_E ..................................................-40°C to +85°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+ = +15V, GND = PGND = 0V, SYNC = REF, I
VL
= I
REF
= 0A,
T
A
= 0°C to +85°C,
unless otherwise noted.)
PARAMETER
3.3V AND 5V STEP-DOWN CONTROLLERS
Input Supply Range
5V Output Voltage (CSL)
3.3V Output Voltage (CSL)
Nominal Adjustable Output
Voltage Range
0 < (CSH - CSL) < 80mV, FB = VL, 6V < V+ < 30V,
includes line and load regulation
0 < (CSH - CSL) < 80mV, FB = 0V, 4.5V < V+ < 30V,
includes line and load regulation
MAX1655
External resistor divider
MAX1652/MAX1653/
MAX1654
MAX1655
Feedback Voltage
CSH - CSL = 0V, CSL = FB,
SKIP
= 0V, 4.5V < V+ < 30V
0 < (CSH - CSL) < 80mV
25mV < (CSH - CSL) < 80mV
6V < V+ < 30V
CSH - CSL, positive
CSH - CSL, negative
V
SS
= 0V
V
SS
= 4V
Falling edge, rising edge, hysteresis = 22mV (MAX1652)
Rising edge, falling edge, hysteresis = 22mV (MAX1654)
SHDN = 2V, 0 < I
VL
< 25mA, 5.5V < V+ < 30V
Rising edge, falling edge hysteresis = 50mV
Rising edge, falling edge hysteresis = 60mV
80
-50
2.5
2.0
2.45
-0.05
4.7
3.8
4.2
2.50
0
5.0
3.9
4.5
2.55
0.05
5.3
4.0
4.7
MAX1652/MAX1653/
MAX1654
4.5
4.85
3.20
1
2.5
0.97
2.43
1.00
2.50
2
1.2
0.03
100
-100
4.0
0.06
120
-160
6.5
5.06
3.34
30
5.25
3.46
5.5
5.5
1.03
2.57
V
V
V
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
Load Regulation
Line Regulation
Current-Limit Voltage
SS Source Current
SS Fault Sink Current
FLYBACK/PWM CONTROLLER
SECFB Regulation Setpoint
%
%/V
mV
µA
mA
V
INTERNAL REGULATOR AND REFERENCE
VL Output Voltage
VL Fault Lockout Voltage
VL/CSL Switchover Voltage
V
V
V
2
_______________________________________________________________________________________
High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
ELECTRICAL CHARACTERISTICS (continued)
(V+ = +15V, GND = PGND = 0V, SYNC = REF, I
VL
= I
REF
= 0A,
T
A
= 0°C to +85°C,
unless otherwise noted.)
PARAMETER
Reference Output Voltage
Reference Fault Lockout Voltage
Reference Load Regulation
CSL, CSH Shutdown Leakage
Current
V+ Shutdown Current
V+ Off-State Leakage Current
Dropout Power Consumption
Quiescent Power Consumption
Falling edge
0 < I
REF
< 100µA
SHDN
= 0V, CSL = 5.5V, CSH = 5.5V, V+ = 0 or 30V,
VL = 0V
SHDN
= 0V, V+ = 30V, CSL = 0 or 5.5V
FB = CSH = CSL = 5.5V, VL switched over to CSL
V+ = 4.5V, CSH = CSL = 4.0V (Note 2)
CSH = CSL = 5.5V
SYNC = REF
SYNC = 0 or 5V
270
125
200
200
Guaranteed by design, not tested
190
SYNC = REF
SYNC = 0 or 5V
SYNC
SHDN, SKIP
SYNC
SHDN, SKIP
SHDN, 0 or 30V
SECFB, 0 or 4V
Input Current
SYNC, SKIP
CSH, CSL, CSH = CSL
≤
4V
FB, FB = REF
DL Sink/Source Current
DH Sink/Source Current
DL On-Resistance
DH On-Resistance
DL forced to 2V
DH forced to 2V, BST - LX = 4.5V
High or low
High or low, BST - LX = 4.5V
1
1
1.5
1.5
5
5
97
98
VL - 0.5
2.0
0.8
0.5
3.0
0.1
1.0
70
±0.1
A
A
Ω
Ω
µA
98
99
200
340
CONDITIONS
No external load (Note 1)
MIN
2.46
2.0
5
0.1
3
5
1
1
300
150
TYP
2.50
MAX
2.54
2.4
15
1
7
15
8
2
330
175
UNITS
V
V
mV
µA
µA
µA
mW
mW
MAX1652–MAX1655
OSCILLATOR AND INPUTS/OUTPUTS
Oscillator Frequency
SYNC High Pulse Width
SYNC Low Pulse Width
SYNC Rise/Fall Time
Oscillator Sync Range
Dropout-Mode Maximum Duty
Cycle
Input High Voltage
Input Low Voltage
kHz
ns
ns
ns
kHz
%
V
V
Note 1:
Since the reference uses VL as its supply, V+ line-regulation error is insignificant.
Note 2:
At very low input voltages, quiescent supply current may increase due to excessive PNP base current in the VL linear
regulator. This occurs if V+ falls below the preset VL regulation point (5V nominal).
_______________________________________________________________________________________
3
High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
MAX1652–MAX1655
ELECTRICAL CHARACTERISTICS (continued)
(V+ = +15V, GND = PGND = 0V, SYNC = REF, IVL = IREF = 0A,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 3)
PARAMETER
3.3V and 5V STEP-DOWN CONTROLLERS
Input Supply Range
5V Output Voltage (CSL)
3.3V Output Voltage (CSL)
0 < (CSH - CSL) < 70mV, FB = VL, 6V < V+ < 30V,
includes line and load regulation
0 < (CSH - CSL) < 70mV, FB = VL, 4.5V < V+ < 30V,
includes line and load regulation
MAX1655
Feedback Voltage
Line Regulation
Current-Limit Voltage
FLYBACK/PWM CONTROLLER
SECFB Regulation Setpoint
Falling edge, hysteresis = 22mV (MAX1652)
Falling edge, hysteresis = 22mV (MAX1654)
SHDN
= 2V, 0 < I
VL
< 25mA, 5.5V < V+ < 30V
Rising edge, hysteresis = 50mV
Rising edge, hysteresis = 60mV
No external load (Note 1)
0 < I
REF
< 100µA
SHDN
= 0V, V+ = 30V, CSL = 0 or 5.5V
FB = CSH = CSL = 5.5V, VL switched over to CSL
2.40
-0.08
4.7
3.75
4.2
2.43
2.60
0.08
5.3
4.05
4.7
2.57
15
10
15
2
SYNC = REF
SYNC = 0 or 5V
250
120
250
250
210
SYNC = REF
SYNC = 0 or 5V
High or low
High or low, BST - LX = 4.5V
97
98
5
5
320
350
180
V
CSH - CSL = 0V, 5V < V+ < 30V,
CSL = FB,
SKIP
= 0V
6V < V+ < 30V
CSH - CSL, positive
CSH - CSL, negative
70
-40
MAX1652/MAX1653/
MAX1654
4.5
4.80
3.16
0.96
2.40
30
5.30
3.50
1.04
2.60
0.06
130
-160
V
V
%/V
mV
V
V
V
CONDITIONS
MIN
TYP
MAX
UNITS
INTERNAL REGULATOR AND REFERENCE
VL Output Voltage
VL Fault Lockout Voltage
VL/CSL Switchover Voltage
Reference Output Voltage
Reference Load Regulation
V+ Shutdown Current
V+ Off-State Leakage Current
Quiescent Power Consumption
OSCILLATOR AND INPUTS/OUTPUTS
Oscillator Frequency
SYNC High Pulse Width
SYNC Low Pulse Width
Oscillator Sync Range
Maximum Duty Cycle
DL On-Resistance
DH On-Resistance
kHz
ns
ns
kHz
%
Ω
Ω
V
V
V
V
mV
µA
µA
mW
Note 3:
Specifications from 0°C to -40°C are guaranteed by design, not production tested.
4
_______________________________________________________________________________________
High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
Typical Operating Circuits
INPUT
4.5V TO 30V
MAX1652–MAX1655
V+
SHDN
VL
MAX1653
MAX1655
DH
+3.3V
OUTPUT
BST
SS
REF
LX
DL
PGND
SYNC
GND
SKIP
FB
CSH
CSL
INPUT
6V TO 30V
V+
SHDN
SECFB
FB
VL
+12V
OUTPUT
MAX1652
DH
+5V
OUTPUT
BST
LX
DL
SS
REF
GND
SYNC
PGND
CSH
CSL
_______________________________________________________________________________________
5
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