POWER MANAGEMENT
1
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SC1214
High Speed, Combi-Sense
TM
Two-Phase, Synchronous MOSFET Driver
Features
Applications
May 9, 2005
The SC1214 is a high speed, Combi-Sense
TM
, two-phase
driver designed to drive high-side and low-side MOSFETs
in two synchronous Buck converters. The driver com-
bined with Combi-Sense PWM controllers, such as
Semtech SC2643VX or SC2643, provides a cost effec-
tive two-phase voltage regulator for advanced micro-
processors
The Combi-Sense
TM
is a technique to sense the inductor
current for peak current mode control of voltage regula-
tor without using sensing resistor. It provides the follow-
ing advantages:
- No costly precision sensing resistor
- Lossless current sensing
- High level noise free signal
- Fast response
- Suitable for wide range of duty cycle
The detailed explanation of the technique can be found
in the Applications Information section.
A 30ns max propagation delay from input transition to
the gate of the power FET’s guarantees operation at high
switching frequencies. Internal overlap protection circuit
prevents shoot-through from Vin
to PGND in the main
and synchronous MOSFETs. The adaptive overlap pro-
tection circuit ensures the bottom FET does not turn on
until the top FET source has reached 1V, to prevent cross-
conduction.
High current drive capability allows fast switching, thus
reducing switching losses at high (up to 1.5MHz) frequen-
cies without causing thermal stress on the driver.
Under-voltage-lockout and over-temperature shutdown
features are included for proper and safe operation.
Timed latches and improved robustness are built into
the housekeeping functions such as the Under Voltage
Lockout and adaptive Shoot-through protection circuitry
to prevent false triggering and to assure safe operation.
The SC1214 is offered in a TSSOP-20 package.
u High efficiency
u +12V gate drive voltage
u High peak drive current
u Adaptive non-overlapping gate drives provide
shoot-through protection
u Support Combi-Sense
TM
and VID-on-fly operations
u Fast rise and fall times (15ns typical with 3000pf
load)
u Ultra-low (<30ns) propagation delay (BG going low)
u Floating top gate drive
u Crowbar function for over voltage protection
u High frequency (to 1.5 MHz) operation allows use
of small inductors and low cost ceramic capacitors
u Under-voltage-lockout
u Low quiescent current
u Intel Pentium® processor power supplies
u AMD Athlon
TM
and AMD-K8
TM
processor power
supplies
u High current low voltage DC-DC converters
Description
