Rainbow Electronics MAX1844 - Manual (Page 2)

MAX1844
High-Speed Step-Down Controller with
Accurate Current Limit for Notebook Computers
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.
V+ to GND ..............................................................-0.3V to +28V
V
CC , V DD to GND .....................................................-0.3V to +6V
OUT, PGOOD, SHDN to GND ..................................-0.3V to +6V
FB, ILIM, LATCH, OVP, REF, SKIP,
TON, UVP to GND ..................................-0.3V to (V CC + 0.3V)
BST to GND ............................................................-0.3V to +34V
CS to GND.................................................................-6V to +30V
DL to GND ..................................................-0.3V to (V
DD + 0.3V)
DH to LX .....................................................-0.3V to (BST + 0.3V)
LX to BST..................................................................-6V to +0.3V
REF Short Circuit to GND ...........................................Continuous
Continuous Power Dissipation (T
A = +70°C)
20-Pin QSOP (derate 9.1mW/
°
C above +70
°
C)...........727mW
20-Pin 5mm ✕ 5mm QFN (derate 20.0mW/°C
above +70°C).................................................................1.60W
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
(Circuit of Figure 1, V+ = 15V, V CC = V DD = 5V, SKIP = GND, T
A
= 0
°
C to +85
°
C , unless otherwise noted. Typical values are at
T A = +25
°
C.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Battery voltage, V+ 2 28
Input Voltage Range
V
CC
, V
DD
4.5 5.5
V
FB = OUT 0.99 1.01
FB = GND 2.475 2.5 2.525
Error Comparator Threshold
(DC Output Voltage Accuracy)
(Note 1)
V+ = 4.5V to 28V,
SKIP = V
CC
FB = V CC 1.782 1.8 1.818
V
Load Regulation Error I
LOAD
= 0 to 3A, SKIP = V
CC
9 mV
Line Regulation Error V CC = 4.5V to 5.5V, V+ = 4.5V to 28V 5 mV
FB Input Bias Current -0.1 +0.1 µA
Output Adjustment Range 1 5.5 V
FB = GND 90 190 350
OUT Input Resistance
FB = V CC or adjustable feedback mode 70 145 270
k Ω
Soft-Start Ramp Time Rising edge of SHDN to full current limit 1.7 ms
TON = GND (600kHz) 140 160 180
TON = REF (450kHz) 175 200 225
TON = unconnected (300kHz) 260 290 320
On-Time
V+ = 24V,
V OUT = 2V
(Note 2)
TON = V CC (200kHz) 380 425 470
ns
Minimum Off-Time (Note 2) 400 500 ns
Quiescent Supply Current (V CC ) FB forced above the regulation point 550 800 µA
Quiescent Supply Current (V DD ) FB forced above the regulation point <1 5 µA
Quiescent Supply Current (V+) 25 40 µA
Shutdown Supply Current (V CC ) SHDN = GND <1 5 µA
Shutdown Supply Current (V
DD
) SHDN = GND <1 5 µA
Shutdown Supply Current (V+) SHDN = GND, V+ = 28V, V
CC = V DD = 0 or 5V <1 5 µA
Reference Voltage V CC = 4.5V to 5.5V, no external REF load 1.98 2.00 2.02 V
Reference Load Regulation I REF = 0 to 50µA 0.01 V