Max1790 low-noise step-up dc-dc converter – Rainbow Electronics MAX1790 User Manual
Page 2
MAX1790
Low-Noise Step-Up DC-DC Converter
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= SHDN = 3V, FREQ = GND, T
A
= 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.
LX to GND ..............................................................-0.3V to +14V
IN, SHDN, FREQ, FB to GND ...................................-0.3V to +6V
SS, COMP to GND .......................................-0.3V to (V
IN
+ 0.3V)
RMS LX Pin Current ..............................................................1.2A
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) ...........330mW
Operating Temperature Range
MAX1790EUA ................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
V
SS
= 1.2V
V
FB
= 1.3V, not switching
V
LX
= 12V
V
IN
rising, typical hysteresis is 40mV,
LX remains off below this level
I
LX
= 1.2A
V
FB
= 1V, duty cycle = 65%
FREQ = IN
∆I = 5µA
FREQ = GND
FREQ = IN
Level to produce V
COMP
= 1.24V,
2.6V < V
IN
< 5.5V
V
FB
= 1.24V
V
FB
= 1.0V, switching
SHDN = GND
FREQ = GND
Level to produce V
COMP
= 1.24V
CONDITIONS
µA
1.5
4
7
Charge Current
Ω
100
Reset Switch Resistance
V/A
0.3
0.45
0.65
R
CS
Current-Sense Transresistance
µA
0.01
20
I
LXOFF
Leakage Current
Ω
0.21
0.5
R
ON
On-Resistance
A
1.2
1.6
2.3
I
LIM
Current Limit (Note 1)
84
%
79
85
92
DC
Maximum Duty Cycle
1000
1220
1500
kHz
540
640
740
f
OSC
Frequency
mA
0.18
0.35
I
IN
Quiescent Current
V
2.25
2.38
2.52
UVLO
V
2.6
5.5
V
IN
Input Supply Range
V
IN
Undervoltage Lockout
V/V
700
A
V
Voltage Gain
µmhos
70
140
240
g
m
Transconductance
%/V
0.05
0.15
Feedback-Voltage Line
Regulation
nA
0
40
I
FB
FB Input Bias Current
2
5
µA
0.1
10
I
IN
Shutdown Supply Current
V
1.222
1.24
1.258
V
FB
Feedback Voltage
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
SHDN, FREQ
SHDN, FREQ; V
IN
= 2.6V to 5.5V
SHDN, FREQ; V
IN
= 2.6V to 5.5V
µA
0.001
1
I
SHDN
SHDN Input Current
µA
1.8
5
9
I
FREQ
FREQ Pull-Down Current
V
0.1
·
V
IN
Hysteresis
V
0.7
·
V
IN
V
IH
Input High Voltage
V
0.3
·
V
IN
V
IL
Input Low Voltage
ERROR AMPLIFIER
OSCILLATOR
N-CHANNEL SWITCH
SOFT-START
CONTROL INPUTS