High Speed, Combi-Sense
TM
Two-Phase, Synchronous MOSFET Driver
POWER MANAGEMENT
Description
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.
SC1214
Features
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High efficiency
+12V gate drive voltage
High peak drive current
Adaptive non-overlapping gate drives provide
shoot-through protection
Support
Combi-Sense
TM
and VID-on-fly operations
Fast rise and fall times (15ns typical with 3000pf
load)
Ultra-low (<30ns) propagation delay (BG going low)
Floating top gate drive
Crowbar function for over voltage protection
High frequency (to 1.5 MHz) operation allows use
of small inductors and low cost ceramic capacitors
Under-voltage-lockout
Low quiescent current
Applications
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Intel Pentium
®
processor power supplies
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AMD Athlon
TM
and AMD-K8
TM
processor power
supplies
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High current low voltage DC-DC converter
s
May 9, 2005
1
www.semtech.com
SEMTECH [ SEMTECH CORPORATION ]
