Datasheet
MAX1954A
Low-Cost, Current-Mode PWM Buck
Controller with Foldback Current Limit
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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, FB to GND...........................................................-0.3V to +6V
LX to BST..................................................................-6V to +0.3V
BST to GND ............................................................-0.3V to +20V
DH to LX................................................... -0.3V to (V
BST
+ 0.3V)
DL, COMP to GND.......................................-0.3V to (V
IN
+ 0.3V)
HSD to GND..............................................................-0.3V to 14V
PGND to GND .......................................................-0.3V to +0.3V
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
Junction Temperature......................................................+150°C
Storage Temperature Range............................+65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V
IN
= 5V, V
BST
- V
LX
= 5V, T
A
= 0°C to +85°C, unless otherwise noted.)
PARAMETER CONDITIONS
MIN TYP MAX
UNITS
GENERAL
Operating Input Voltage Range
3.0 5.5 V
HSD Voltage Range (Note 1) 3.0
13.2
V
Quiescent Supply Current V
FB
= 1.5V 1 2
mA
Standby Supply Current
V
IN
= V
BST
= 5.5V, V
HSD
= 13.2V, LX = unconnected,
COMP = GND
2
mA
Undervoltage-Lockout Trip Level
Falling V
IN
, 50mV (typ) hysteresis 2.5 2.7 2.9 V
DC-DC CONTROLLER
Output-Voltage Adjust Range
(V
OUT
)
Maximum output voltage depends on external components
and maximum duty cycle
0.8 V
ERROR AMPLIFIER
FB Regulation Voltage
-1.0 +0.8 +1.0
%
Transconductance 70
110 160
µS
Voltage Gain
200
V/ V
FB Input Leakage Current V
FB
= 0.9V 50
500
NA
FB Input Common-Mode Range
-0.1
+1.5
V
COMP Output-Voltage Swing
0.80
2.36
V
Current-Sense Amplifier
Voltage Gain
3.15
3.5
3.85
V / V
V
FB
= 0.8V
110 135 145
Current-Limit Threshold V
PGND
- V
LX
V
FB
= 0V 21 36 51
mV
OSCILLATOR
Switching Frequency MAX1954A
240 300 360
kHz
Maximum Duty Cycle Measured at DH 89 91 93 %
Minimum Duty Cycle V
COMP
= 1.25V, LX = GND, V
BST
= V
IN
= 3.3V 2.5 3 %