Datasheet

MAX8537/MAX8538/MAX8539
Dual-Synchronous Buck Controllers for Point-of-
Load, Tracking, and DDR Memory Power Supplies
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 +25V
AVL, VL to GND........................................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
FB_, EN_, POK_ to GND...........................................-0.3V to +6V
REFIN, VTTR, FREQ, SS_, COMP_ to GND....-0.3V to (AVL + 0.3V)
BST_, ILIM_ to GND ...............................................-0.3V to +30V
DH1 to LX1 ...............................................-0.3V to (BST1 + 0.3V)
DH2 to LX2 ...............................................-0.3V to (BST2 + 0.3V)
LX_ to BST_ ..............................................................-6V to +0.3V
LX_ to GND................................................................-2V to +25V
DL_ to PGND ................................................-0.3V to (VL + 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
28-Pin QSOP (derate 10.8mW/°C above +70°C)........860mW
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+ = 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
GENERAL
V+ Operating Range VL regulator drops out below 5.5V (Note 1) 4.5 23.0 V
V+/ VL Operating Range VL is externally generated (Note 1) 4.5 5.5 V
V+ Operating Supply Current IL(VL) = 0, FB_ forced 50mV above threshold 3.5 7 mA
V+ Standby Supply Current IL(VL) = 0, BST_ = VL, EN = LX_ = FB_ = 0V 350 700 µA
VL REGULATOR
Output Voltage 5.5V < V+ < 23V, 1mA < I
LOAD
< 70mA 4.75 5 5.25 V
VL Undervoltage-Lockout Trip
Level
Rising edge, hysteresis = 550mV (typ) (trip level is
typically 85% of VL)
4.18 4.3 4.42 V
Output Current
This is for gate current of DL_ /DH_ drivers, C(VL) =
1µF/10mA ceramic capacitor
70 mA
Thermal Shutdown Rising temperature, typical hysteresis = 10°C +160 °C
CURRENT-LIMIT THRESHOLD (all current limits are tested at V+ = VL = 4.5V and 5.5V)
ILIM Sink Current ILIM_ = LX - 200mV, 1.8V < LX < 23V, BST = LX +5V 180 200 220 µA
SOFT-START
Soft-Start Source Current SS_ = 100mV -7 -5 -3 µA
Soft-Start Sink Current SS_ = 0.8 or REFIN 3 5 7 µA
Soft-Start Full-Scale Voltage
0.8 or
REFIN
V
FREQUENCY
Low End of Range R
FREQ
= 100kΩ, V+ = VL = 5V 160 200 240 kHz
Intermediate Range R
FREQ
= 20kΩ, V+ = VL = 5V 800 1000 1200 kHz
High End of Range R
FREQ
= 14.3kΩ, V+ = VL = 5V 1120 1400 1680 kHz
R
FREQ
= 100kΩ 95
R
FREQ
= 20kΩ 80 Maximum Duty Cycle
R
FREQ
= 14.3kΩ 72
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