MAX1519 Datasheet, PDF (19/43 Pages) Maxim Integrated Products – Dual-Phase, Quick-PWM Controllers for Programmable CPU Core Power Supplies

Dual-Phase, Quick-PWM Controllers for
Programmable CPU Core Power Supplies
SHDN
VID (D0–D4)
SOFT-START
1LSB PER R_TIME CYCLE
V_CORE
DO NOT CARE
SOFT-SHUTDOWN
1LSB PER 4 R_TIME CYCLES
VROK
t_VROK(START)
3ms, TYP
Figure 2. Power-Up and Shutdown Sequence Timing Diagram
Table 2. Component Suppliers
MANUFACTURER
BI Technologies
Central Semiconductor
Coilcraft
Coiltronics
Fairchild Semiconductor
International Rectifier
Kemet
Panasonic
Sanyo
Siliconix (Vishay)
Sumida
Taiyo Yuden
TDK
TOKO
PHONE
714-447-2345 (USA)
631-435-1110 (USA)
800-322-2645 (USA)
561-752-5000 (USA)
888-522-5372 (USA)
310-322-3331 (USA)
408-986-0424 (USA)
847-468-5624 (USA)
65-6281-3226 (Singapore)
203-268-6261 (USA)
408-982-9660 (USA)
03-3667-3408 (Japan)
408-573-4150 (USA)
847-803-6100 (USA)
81-3-5201-7241 (Japan)
858-675-8013 (USA)
WEBSITE
www.bitechnologies.com
www.centralsemi.com
www.coilcraft.com
www.coiltronics.com
www.fairchildsemi.com
www.irf.com
www.kemet.com
www.panasonic.com
www.secc.co.jp
www.vishay.com
www.sumida.com
www.t-yuden.com
www.component.tdk.com
www.tokoam.com
where f_SLEW = 500kHz ✕ 30kΩ/R_TIME, V_DAC is the DAC
setting when the controller begins the shutdown
sequence, and V_LSB = 25mV is the DAC’s smallest volt-
age increment. Slowly discharging the output capacitors
by slewing the output over a long period of time
(4/f_SLEW) keeps the average negative inductor current
low (damped response), thereby eliminating the nega-
tive output voltage excursion that occurs when the con-
troller discharges the output quickly by permanently
turning on the low-side MOSFET (underdamped
response).
This eliminates the need for the Schottky diode normally
connected between the output and ground to clamp the
negative output voltage excursion. When the DAC
reaches the 0V setting, DL_ goes high, DH_ goes low,
the reference turns off, and the supply current drops to
about 1µA. When a fault condition—output undervoltage
lockout, output overvoltage lockout (MAX1545), or ther-
mal shutdown—activates the shutdown sequence, the
controller sets the fault latch to prevent the controller from
restarting. To clear the fault latch and reactivate the con-
troller, toggle SHDN or cycle V_CC power below 1V.
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