User Manual

MAX1540/MAX1541
Dual Step-Down Controllers with Saturation
Protection, Dynamic Output, and Linear Regulator
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 15V, V
CC
= V
DD
= ON1 = ON2 = 5V, SKIP = GND, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FB_ = GND 70 145 350
MAX1540
FB_ = V
CC
or
adjustable
50 115 220
FB1 = OUT1 400 700 1500
FB2 = GND 90 170 350
OUT_ Input Resistance R
OUT
_
MAX1541
FB2 = V
CC
or
adjustable
60 130 270
kΩ
OUT_ Discharge Mode On-
Resistance
R
D IS C H ARGE
10 25 Ω
OUT_ Synchronous-Rectifier
Discharge-Mode Turn-On Level
0.2 0.3 0.4 V
Soft-Start Ramp Time t
SS
Rising edge on ON_ to full current limit 1.7 ms
TON = GN D ( 620kH z)
149 169 190
TON = REF (485kHz) 191 216 242
TON = op en ( 345kH z) 274 304 335
DH1 On-Time t
ON1
V+ = 15V,
V
OUT1
= 1.5V
(Note 3)
TON = V
CC
(235kHz) 402 447 491
ns
TON = GN D ( 460kH z) 201 228 256
TON = REF (355kHz) 260 296 331
TON = op en ( 255kH z) 371 412 453
DH2 On-Time t
ON2
V+ = 15V,
V
OUT2
= 1.5V
(Note 3)
TON = V
CC
(170kHz) 556 618 679
ns
On-Time Tracking t
ON2
with respect to t
ON1
(Note 3) 120 135 150 %
Minimum Off-Time t
OFF
(
MIN
)
(Note 3) 400 500 ns
LINEAR REGULATOR (LDO) (Note 1)
0 < I
LDOOUT
< 10mA 4.85 5.0 5.10
MAX1540 LDO Output-Voltage
Accuracy
V
LDOOUT
ON1 = ON2 = GND,
V+ = 6V to 28V
0 < I
LD OOU T
< 100m A 4.70 5.10
V
0 < I
LDOOUT
< 10mA 4.85 5.0 5.10
MAX1541 LDO Output-Voltage
Accuracy (Fixed V
LDOOUT
)
V
LDOOUT
FBLDO = ON1 =
ON2 = GND,
V
LDOIN
= 6V to 28V
0 < I
LD OOU T
< 100m A 4.70 5.10
V
0 < I
LDOOUT
< 10mA 1.212 1.25 1.275
MAX1541 LDO Feedback
Accuracy (Adjustable V
LDOOUT
)
V
FBLDO
FBLDO = LDOOUT,
ON1 = ON2 = GND,
V
LDOIN
= 4.5V to
28V
0 < I
LD OOU T
< 100m A 1.175 1.275
V
MAX1541 LDO Output
Adjust Range
1.175 24 V
LDOOUT Short-Circuit Current 130 mA
FBLDO Input Bias Current I
FBLDO
-0.1 +0.1 µA
MAX1540: V+ - V
LDOOUT
500 800
Dropout Voltage
MAX1541: V
LDOIN
- V
LDOOUT
500 800
mV