Maxim MAX1692EUB Datasheet
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General Description
The MAX1692 is a low-noise, pulse-width-modulated
(PWM), DC-DC step-down converter. It powers logic
and transmitters in small wireless systems such as cellular phones, communicating PDAs, and handy-terminals.
The device features an internal synchronous rectifier for
high efficiency; it requires no external Schottky diode.
Excellent noise characteristics and fixed-frequency
operation provide easy post-filtering. The MAX1692 is
ideally suited for Li-Ion battery applications. It is also
useful for +3V or +5V fixed input applications.
The device operates in one of four modes. Forced PWM
mode operates at a fixed frequency regardless of the
load. Synchronizable PWM mode allows an external
switching frequency to control and minimize harmonics.
Idle Mode™ (PWM/PFM) extends battery life by switching to a PFM pulse-skipping mode during light loads.
Shutdown mode places the device in standby, reducing quiescent supply current to under 0.1µA.
The MAX1692 can deliver over 600mA. The output voltage can be adjusted from 1.25V to VINwith the input
range of +2.7V to +5.5V. Other features of the
MAX1692 include high efficiency, low dropout voltage,
and a 1.2%-accurate 1.25V reference. It is available in
a space-saving 10-pin µMAX package with a height of
only 1.11mm.
Applications
Cellular Phones CPU I/O Supplies
Cordless Phones Notebook Chipset Supplies
PDAs and Handy-Terminals Battery-Operated Devices
(1 Li-Ion or 3 NiMH/NiCd)
Features
♦ +2.7V to +5.5V Input Range
♦ Adjustable Output from 1.25V to V
IN
♦ 600mA Guaranteed Output Current
♦ 95% Efficiency
♦ No Schottky Diode Required
♦ 85µA Quiescent Current
♦ 100% Duty Cycle in Dropout
♦ 750kHz Fixed-Frequency PWM Operation
♦ Synchronizable Switching Frequency
♦ Accurate Reference: 1.25V (±1.2%)
♦ Small 10-Pin µMAX Package
MAX1692
Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
________________________________________________________________
Maxim Integrated Products
1
1
2
3
4
5
10
9
8
7
6
PGND
LX
SHDN
SYNC/PWMREF
GND
BP
IN
MAX1692
TOP VIEW
LIMFB
µMAX
19-1400; Rev 0; 11/98
PART
MAX1692EUB -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
10 µMAX
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
Idle Mode is a trademark of Maxim Integrated Products.
Pin Configuration
Ordering Information
Typical Operating Circuit
MAX1692
FB
SYNC/PWM
PGND
BP
LIM
LX
SHDN
IN
L
C2
R1
R2
C4
C3
C1
V
IN
= 2.7V TO 5.5V V
OUT
= 1.25V TO V
IN
AGND REF
MAX1692
Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN= +3.6V, SYNC/PWM = GND, V
LIM
= 3.6V, SHDN = IN, circuit of Figure 2; TA= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°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.
IN, BP, SHDN, SYNC/PWM, LIM to GND ................ -0.3V to +6V
BP to IN .................................................................-0.3V to +0.3V
PGND to GND ...................................................... -0.3V to +0.3V
LX to PGND................................................. -0.3V to (V
IN
+ 0.3V)
FB, REF to GND......................................... -0.3V to (V
BP
+ 0.3V)
Reference Current............................................................. ±1mA
LX Peak Current (internally limited)...................................... 1.6A
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C)............444mW
Operating Temperature Range .......................... -40°C to +85°C
Maximum Junction Temperature .................................... +150°C
Storage Temperature Range............................ -65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
(Note 1)
FB = OUT, VIN= V
LIM
= 2.7V to 5.5V,
I
OUT
= 0
SHDN = LX = GND, includes LX leakage
current
SYNC/PWM = GND, VFB= 1.4V,
LX unconnected
ILX= 180mA
SYNC/PWM = IN, FB = REF
VFB= 1.4V
VIN= 3.6V
FB = OUT, VIN= V
LIM
= 5.5V, I
OUT
= 0
(duty cycle = 23%) (Note 2)
Duty cycle = 100% to 23%
I
OUT
= 0 to 600mA, LIM = IN or
I
OUT
= 0 to 250mA, LIM = GND
LIM = IN
VFB= 1.4V
LIM = GND
CONDITIONS
µA0.1 10Shutdown Supply Current
µA85 140Quiescent Current
mA80 120 160
Pulse-Skipping Current-Limit
Threshold
0 50 100
mA
-450 -850 -1600
N-Channel Current-Limit
Threshold
0.75 1.2 1.55
A
0.35 0.6 0.85
P-Channel Current-Limit
Threshold
VV
REF
V
IN
Output Adjustment Range
1.223 1.249 1.275
V2.7 5.5V
IN
Input Voltage Range
0.5
Ω
0.4 0.8
N
RDS(ON)
N-Channel On-Resistance
0.4
Ω
0.3 0.65
P
RDS(ON)
P-Channel On-Resistance
V1.223 1.249 1.275V
FB
Feedback Voltage
%+1Line Regulation
%-1.3Load Regulation
nA-50 0.01 50I
FB
FB Input Current
UNITSMIN TYP MAXSYMBOLPARAMETER
VIN= 5.5V, VLX= 0 or 5.5V µA-20 0.1 20LX Leakage Current
kHz650 750 830f
OSC
Oscillator Frequency
kHz500 1000SYNC Capture Range
%100duty
MAX
Maximum Duty Cycle
%22duty
MIN
Minimum Duty Cycle
I
REF
= 0 V1.235 1.250 1.265V
REF
Reference Output Voltage
FB = OUT, VIN= 2.7V to 5.5V,
I
OUT
= 0 to 600mA, LIM = IN or
I
OUT
= 0 to 250mA, LIM = GND
V
1.190 1.232 1.275
V
OUT
Output Voltage
ILX= 180mA
VIN= 2.7V
VIN= 3.6V
VIN= 2.7V
MAX1692
Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
_______________________________________________________________________________________ 3
Note 1: Guaranteed by minimum and maximum duty-factor tests.
Note 2: The following equation can be used to calculate FB accuracy for output voltages other than 1.232V:
(see Feedback Voltage vs. Load Current)
V
FB
= V
FB (NOMINAL)
- (Line Reg) (V
OUT
/ VIN- 0.23) / 0.77 - (Load Reg)(I
OUT
+ 0.5 · I
RIPPLE
) / I
MAX
where: Line Reg = the line regulation
Load Reg = the load regulation
I
RIPPLE
= (1- V
OUT
/ VIN) · V
OUT
/ (f
OSC
· L) where L is the inductor value
I
MAX
= 250mA (LIM = GND) or 600mA (LIM = IN)
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(VIN= +3.6V, SYNC/PWM = GND, V
LIM
= 3.6V, SHDN = IN, circuit of Figure 2; TA= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)
High or low
0 ≤ I
REF
≤ 50µA
SHDN, SYNC/PWM, LIM
CONDITIONS
ns500
SYNC/PWM Minimum Pulse Width
mV3 15Reference Load Regulation
µA-1 0.1 1Logic Input Current
UNITSMIN TYP MAXSYMBOLPARAMETER
(Note 1)
FB = OUT, VIN= V
LIM
= 2.7V to 5.5V,
I
OUT
= 0
SYNC/PWM = GND, LX = unconnected,
VFB= 1.4V
FB = OUT, VIN= V
LIM
= 5.5V, I
OUT
= 0
(duty cycle = 23%) (Note 2)
VFB=1.4V
LIM = IN
CONDITIONS
VREF V
IN
Output Adjustment Range
1.213 1.285
V2.7 5.5V
IN
Input Voltage Range
µA140Quiescent Current
V1.213 1.285V
FB
Feedback Voltage
nA-50 50I
FB
FB Input Current
A
0.7 1.6
P-Channel Current-Limit
Threshold
mA
N-Channel Current-Limit
Threshold
UNITSMIN MAXSYMBOLPARAMETER
ELECTRICAL CHARACTERISTICS
(VIN= +3.6V, SYNC/PWM = GND, V
LIM
= 3.6V, SHDN = IN, circuit of Figure 2, TA= -40°C to +85°C, unless otherwise noted.) (Note 3)
LIM = GND
SYNC/PWM = IN, FB = REF -15 110
SHDN = LX = GND, includes LX leakage current
µA10Shutdown Supply Current
kHz630 840f
OSC
Oscillator Frequency
I
REF
= 0 V1.230 1.268V
REF
Reference Output Voltage
VINrising, typical hysteresis is 85mV V2.3 2.5UVLO
Undervoltage Lockout
Threshold
SHDN, SYNC/PWM, LIM
V2V
IH
Logic Input High
SHDN, SYNC/PWM, LIM
V0.4V
IL
Logic Input Low
SHDN, SYNC/PWM, LIM
µA-1 1Logic Input Current
0.3 0.9
SHDN, SYNC/PWM, LIM
V0.4V
IL
Logic Input Low
VINrising, typical hysteresis is 85mV V2.3 2.4 2.5UVLOUndervoltage Lockout Threshold
SHDN, SYNC/PWM, LIM
V2V
IH
Logic Input High
FB = OUT, VIN= 2.7V to 5.5V,
I
OUT
= 0 to 600mA, LIM = IN or
I
OUT
= 0 to 250mA, LIM = GND
V
1.185 1.285
V
OUT
Output Voltage
1.74
1.76
1.80
1.78
1.82
1.84
0 400300200100 500 600 700 800 900
OUTPUT VOLTAGE vs.
LOAD CURRENT
MAX1692-10
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = 2.7V
V
OUT
= 1.8V
R1 = 138kΩ
R2 = 301kΩ
MAX1692
Low-Noise, 5.5V-Input,
PWM Step-Down Regulator
4 _______________________________________________________________________________________
0
200
100
400
300
500
600
0 300 450150 600 750 900
DROPOUT VOLTAGE vs.
LOAD CURRENT
MAX1692-01
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
V
OUT
= 2.5V
V
OUT
= 3.3V
95
50
1 100010010
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 3.3V)
65
55
85
75
100
70
60
90
80
MAX1692-02
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 5.0V
VIN = 3.6V
LIM = IN
R1 = 505kΩ
R2 = 301kΩ
95
50
1 100010010
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 2.5V)
65
55
85
75
100
70
60
90
80
MAX1692-03
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 5.0V
VIN = 2.7V
VIN = 3.6V
LIM = IN
R1 = 309kΩ
R2 = 301kΩ
95
50
1 100010010
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 1.8V)
65
55
85
75
100
70
60
90
80
MAX1692-04
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 2.7V
VIN = 5.0V
VIN = 3.6V
LIM = IN
R1 = 138kΩ
R2 = 301kΩ
0
1.5
1.0
0.5
2.5
2.0
4.5
4.0
3.5
3.0
5.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
BATTERY INPUT CURRENT vs.
INPUT VOLTAGE
MAX1692-07
INPUT VOLTAGE (V)
BATTERY INPUT CURRENT (mA)
SYNC/PWM = IN
V
OUT
= 3.3V
V
OUT
= 1.8V
V
OUT
= 2.5V
1.2
1.21
1.205
1.225
1.22
1.215
1.245
1.24
1.235
1.23
1.25
0 300100 200 400 500 600 700 800 900 1000
FEEDBACK VOLTAGE
vs. LOAD CURRENT
MAX1692-05
LOAD CURRENT (mA)
FB VOLTAGE (V)
VIN = 5.0V
R1 = 309kΩ
R2 = 301kΩ
SYNC/PWM = GND
LIM = IN
LIM = GND
60
70
65
80
75
95
90
85
100
2.7 3.53.1 3.9 4.3 4.7 5.1 5.5
BATTERY INPUT CURRENT vs.
INPUT VOLTAGE
MAX1692-06
INPUT VOLTAGE (V)
BATTERY INPUT CURRENT (µA)
V
OUT
= 1.8V
SYNC/PWM = GND
TA = +85°C
TA = +25°C
TA = -40°C
1.0
1.5
2.0
2.5
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
BATTERY INPUT CURRENT vs. INPUT
VOLTAGE AND TEMPERATURE
MAX1692-09
INPUT VOLTAGE (V)
BATTERY INPUT CURRENT (mA)
V
OUT
= 1.8V
SYNC/PWM = IN
TA = +85°C
TA = +25°C
TA = -40°C
Typical Operating Characteristics
(SYNC/PWM = GND, circuit of Figure 2, L = Sumida CD43-100, TA = +25°C, unless otherwise noted.)
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