l6712a STMicroelectronics, l6712a Datasheet - Page 7

• Manufacturer Part Number: l6712a
• Description: Two-phase Interleaved Dc/dc Controller
• Manufacturer: STMicroelectronics

REFERENCE SCHEMATIC
DEVICE DESCRIPTION
The device is an integrated circuit realized in BCD technology. It provides complete control logic and pro-
tections for a high performance dual-phase step-down converter optimized for high current DC/DC appli-
cations. It is designed to drive N-Channel Mosfets in a two-phase synchronous-rectified buck topology. A
180 deg phase shift is provided between the two phases allowing reduction in the input capacitor current
ripple, reducing also the size and the losses. The output voltage of the converter can be precisely regu-
lated, programming the VID pins, from 0.900 to 3.300V with a maximum tolerance of ±0.9% over temper-
ature and line voltage variations. The programmable Remote Sense Amplifier avoids the use of external
resistor divider allowing recovering drops across distribution lines and also adjusting output voltage to dif-
ferent values from the available reference. The device provides an average current-mode control with fast
transient response. It includes a 150kHz free-running oscillator externally adjustable through a resistor.
The error amplifier features a 15V/µs slew rate that permits high converter bandwidth for fast transient per-
formances. Current information is read across the lower mosfets R
in series to the LS mos in fully differential mode. The current information corrects the PWM outputs in order
to equalize the average current carried by each phase. Current sharing between the two phases is then
limited at ±10% over static and dynamic conditions unless considering the sensing element spread. Droop
effect can be programmed in order to minimize output filter and load transient response: the function can
be disabled and the current information available on the pin can be used for other purposes. The device
protects against Over-Current, with an OC threshold for each phase, entering in constant current mode.
Since the current is read across the low side mosfets, the device keeps constant the bottom of the induc-
tors current triangular waveform. When an Under Voltage is detected the device resets with all mosfets
OFF and suddenly re-starts. The device also performs a crowbar Over-Voltage protection that immediate-
ly latches the operations turning ON the lower driver and driving high the FAULT pin.
GNDin
Vin
S2
S1
S0
L1
HS1
LS1
REF_IN/OUT
Rg
Rg
OSC / INH
LGATE1
VCCDR
UGATE1
PHASE1
PGNDS1
BOOT1
ISEN1
SGND
VID0
VID2
VID1
FBR
L6712A
L6712
FBG
DROOP
VSEN
VCC
BOOT2
UGATE2
PHASE2
LGATE2
ISEN2
PGNDS2
PGND
PGOOD
COMP
FB
Rg
Rg
C
R
R
F
F
FB
HS2
LS2
dsON
or across a sense resistor placed
L2
C
C
IN
OUT
L6712A L6712
PGOOD
LOAD
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