SC1405B

Manufacturer Part NumberSC1405B
DescriptionHigh Speed Synchronous Power MOSFET Smart Driver
ManufacturerSemtech Corporation
SC1405B datasheet
 


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POWER MANAGEMENT
Description
The SC1405B is a Dual-MOSFET Driver with an internal
Overlap Protection Circuit to prevent shoot-through. Each
driver is capable of driving a 3000pF load in 15ns rise/
fall time and has ULTRA-LOW propagation delay from in-
put transition to the gate of the power FET’s. Adaptive
Overlap Protection circuit ensures that the synchronous
FET does not turn on until the top FET source has reached
a voltage low enough to prevent shoot-through. The de-
lay between the bottom gate going low to the top gate
transitioning high is externally programmable via a ca-
pacitor to minimize dead time. The bottom FET may be
disabled at light loads by keeping S_MOD low to trigger
asynchronous operation, thus saving the bottom FET’s
gate drive current and inductor ripple current. An inter-
nal voltage reference allows threshold adjustment for
an Output Over-Voltage protection circuitry, independent
of the PWM controller.
Under-Voltage-Lock-Out circuit is included to guarantee
that both driver outputs are off when Vcc is less than or
equal to 4.4V (typ) at supply ramp up (4.35V at supply
ramp down). A CMOS output provides status indication
of the 5V supply. A low enable input places the IC in stand-
by mode, reducing supply current to less than 10µA.
SC1405B is offered in a high pitch (.025” lead spacing)
TSSOP package.
Typical Application Circuit
INPUT POWER, 5-20V
Vcc
+
10uF,6.3V
.1uF
<<
P_READY
>>
PWM IN
(20KHz-1MHz)
47pF
<<
DSPS_DR
<<< Output Feedback to PWM
Controller
Revision: January 13, 2004
High Speed Synchronous Power
Features
Fast rise and fall times (15ns with 3000pf load)
14ns max. Propagation delay (BG going low)
Adaptive and programmable shoot-through
protection
Wide input voltage range (4.5-25V)
Power saving asynchronous mode control
Output overvoltage protection/overtemp shutdown
Under-Voltage lock-out and power ready signal
Less than 10µA stand-by current (EN=low)
Improved drive version of SC1405TS
High frequency (to 1.2MHz) operation allows use of
small inductors and low cost capacitors in place of
electrolytics
Applications
High Density/Fast transient microprocessor power
supplies
Motor Drives/Class-D amps
High efficiency portable computers
+
+
+
5817
.22uF
8
14
3
13
7
2.2
2
12
4
6
SC1405
9
1
11
2.2
5
10
Over-Voltage Sense
1
SC1405B
MOSFET Smart Driver
MTB75N03
75A,30V
1.7V@30A
+
+
+
MTB75N03
75A,30V
www.semtech.com

SC1405B Summary of contents

  • Page 1

    ... A CMOS output provides status indication of the 5V supply. A low enable input places the IC in stand- by mode, reducing supply current to less than 10µA. SC1405B is offered in a high pitch (.025” lead spacing) TSSOP package. Typical Application Circuit INPUT POWER, 5-20V ...

  • Page 2

    ... µ SC1405B < ...

  • Page 3

    ... ° SC1405B ...

  • Page 4

    ... > SC1405B ...

  • Page 5

    ... POWER MANAGEMENT Timing Diagrams 2004 Semtech Corp. 5 SC1405B www.semtech.com ...

  • Page 6

    ... µ SC1405B ...

  • Page 7

    ... Class- D amplifiers. Theory of Operation The control input (CO) to the SC1405B is typically sup- plied by a PWM controller that regulates the power sup- ply output. (See Application Evaluation Schematic, Fig- ure 3). The timing diagram demonstrates the sequence 2004 Semtech Corp ...

  • Page 8

    ... FET. This is assuming that the impedance of the drive path is too high compared to the instantaneous imped- ance of the capacitors. (since dV/dT and thus the effec- tive frequency is very high). If the BG pin of the SC1405B is very close to the bottom FET, Vspike will be reduced depending on trace inductance, rate if rise of current,etc. ...

  • Page 9

    ... MOSFETs will reduce lead induc- tance and their parasitic effects. ASYNCHRONOUS OPERATION The SC1405B can be configured to operate in Asynchro- nous mode by pulling S-MOD to logic LOW, thus disabling the bottom FET drive. This has the effect of saving power at light loads since the bottom FET’s gate capacitance does not have to charged at the switching frequency ...

  • Page 10

    ... Figure 3: PWM input and Gate drive and phase node switching waveforms with time scale expanded. The MOSFETs driven are shown on Figure 4 (Evaluation Board Schematic) Ch1: PWM input signal Ch2: Top Gate Drive Ch3: Phase (Switching) Node Ch4: Bottom Gate 10 SC1405B www.semtech.com ...

  • Page 11

    ... TION EVAL AL AL ALU TION BO AL 1000uf,16V 1u,16V 2004 Semtech Corp. TION BO TION BO TION BO TION BOARD SCHEMA ARD SCHEMATIC ARD SCHEMA ARD SCHEMA ARD SCHEMA TIC TIC TIC TIC Controller. SC2422 the disables OFF VIDs All 11 SC1405B www.semtech.com ...

  • Page 12

    ... 2004 Semtech Corp SC1405B ...

  • Page 13

    ... POWER MANAGEMENT Outline Drawing -TSSOP-14 Land Pattern - TSSOP-14 Contact Information Phone: (805)498-2111 FAX (805)498-3804 2004 Semtech Corp. Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 13 SC1405B www.semtech.com ...