Datasheet

MAX8537/MAX8538/MAX8539
Dual-Synchronous Buck Controllers for Point-of-
Load, Tracking, and DDR Memory Power Supplies
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ELECTRICAL CHARACTERISTICS (continued)
(V+ = 12V, EN_ = VL, BST_ = 6V, LX_ = 1V, VL load = 0mA, C
VL
= 10µF (ceramic), REFIN = 1.25V, PGND = AGND = FB_ = ILIM_ =
0V, C
SS
= 10nF, C
VTTR
= 1µF, R
FREQ
= 20kΩ, DH_ = open, DL_ = open, POK_ = open, circuit of Figure 1, T
A
= 0°C to +85°C, unless
otherwise noted.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
R
FREQ
= 100kΩ 2.4 4
R
FREQ
= 20kΩ 12 18Minimum Duty Cycle
R
FREQ
= 14.3kΩ 16 25
%
DH_ Minimum Off-Time 140 200 ns
DH_ Minimum On-Time 120 ns
ERROR AMPLIFIER
FB_ Input Bias Current V
FB
_ = 0.8V 250 nA
FB1 Input-Voltage Set Point Over line and load 0.792 0.800 0.808 V
MAX8538 0.792 0.800 0.808
FB2 Input-Voltage Set Point
MAX8537/MAX8539, REFIN = 0.9V 0.894 0.900 0.906
V
Op-Amp Open-Loop Voltage
Gain
COMP_ = 1.3V to 2.3V 72 >80 dB
Op-Amp Gain Bandwidth 25 MHz
Op-Amp Output-Voltage Slew
Rate
15 V/µs
DRIVERS
Break-Before-Make Time 30 ns
DH1, DH2 On-Resistance in Low
State
0.9 2.5 Ω
DH1, DH2 On-Resistance in High
State
1.3 2.5 Ω
DL1, DL2 On-Resistance in Low
State
0.7 1.5 Ω
DL1, DL2 On-Resistance in High
State
1.6 2.8 Ω
LOGIC INPUTS (EN_)
Input Low Level 4.5V < VL < 5.5V 0.8 V
Input High Level 4.5V < VL < 5.5V 2.4 V
Input Bias Current 0V to 5.5V -1 +0.1 +1 µA
VTTR
VTTR Output Voltage Range Source or sink 15mA 0.5 2.5 V
VTTR Output Accuracy -15mA ≤ I
VTTR
≤ +15mA, REFIN = 0.9V or 1.25V -1.0 REFIN +1.0 %
REFIN
REFIN Input Bias Current REFIN = 0.9V or 1.25V -250 +250 nA