1. FAN3268 and FAN3278 Low-Voltage Bridge Drivers
January, 2010
Power Conversion America

2. FAN3268/78 Low-Voltage Bridge Drivers 2A Low-Voltage PMOS-NMOS Bridge Drivers
FAN3268: 4.5 V to 18 V Operating Range
FAN3278: 8 V to 27 V Operating Range
Drives High-Side PMOS and Low-Side NMOS for
Battery-Powered Compact Brushless-dc Motor Drives in Industrial, Medical and Automotive applications such as 12-V blower motors.
Two Independent Enable Pins for Design Flexibility
Operation Default to ON if not connected
Suitable with FDD8424H Dual MOSFETs (40 V, 20 A) in 4-lead DPAK
TTL input thresholds
SOIC package
–40°C to +125°C ambient

3. FAN3268 and FAN3278 2A Low-Voltage PMOS-NMOS Bridge Drivers
Fairchild Semiconductor’s FAN3268 and FAN3278 are a special low-voltage high-performance bridge drivers for fan/pump DC motor drive applications with PMOS/NMOS Half-Bridge configuration.
Battery-Powered Compact Brushless-dc Motor Drives in Industrial, Medical and Automotive applications such as 12V blower motors.
Interface between a sensitive PWM or DSP and the MOSFETs. This device also features robust ESD protection
Key Features
TTL input thresholds to provide buffer and level translation functions from logic inputs.
Internal circuitry provides an under-voltage lockout function that prevents the switching if the VDD supply voltage is below the operating level. If an input is left unconnected, internal resistors bias the inputs such that keeps the external MOSFETs OFF.
Included also are two enable pins, a key feature during medical device power-up, that default to ON if not connected.

4. FAN3268 and FAN3278 Typical 3-Phase Blower Motor Application

5. FAN3278 vs. FAN3268 FAN3278 FAN3268 Supply Voltage
27 V Operating Maximum
30 V Absolute Maximum
18 V Operating Maximum
20 V Absolute Maximum
Gate Drive Regulator
Yes, since the maximum operating VDD can be as high as 27 V, the gate voltage to the external MOSFETs is limited to about 13V.
No gate drive regulator needed. The gate drive voltage is VDD and the FAN3268 switches rail-to-rail.
Minimum Operating Voltage
The optimum operating range is 8 V to 27 V. After the IC turns on at about 3.8 V, the output tracks VDD up to the regulated voltage rail of about 11~13 V. Below 8 V of VDD, the FAN3278 operates, but (a) slower and (b) with limited gate drive voltage until it reaches around 8 V.
4.1 V is the UVLO turn-off voltage which is the minimum operating voltage.
Start-up
The IC starts operating approximately at 3.8 V which acts as a loose UVLO threshold. It incorporates a “smart startup” feature where the outputs are held OFF before the IC starts operating.
Has the tight UVLO threshold of 4.5V on / 4.1V off. Incorporates “smart startup” (outputs held OFF before IC is fully operational at the UVLO threshold).
Output Gate Drive Architecture
Standard MOS-based output structure with gate drive clamp feature.
Compound MillerDrive™ architecture in the final output stage to provide a more efficient gate drive current during the Miller plateau stage of the turn-on/turn-off switching transition.
OUTB Gate Drive Current Strength for P-Channel MOSFETs
Optimized for P-channel: The turn-OFF
(1.5 A) is stronger than turn-ON (1.0A).
P-channel turn-ON (2.4A) is stronger than turn-OFF (1.6A).

6. High-Speed Low-Side Gate Drivers FAN3268 and FAN3278: Part of the Family
Type
Configuration
Part Num
In. Thres.
Packages
Released
Single 1A
Dual Input (CMOS); Non-Inv (Ext)
FAN3111
CMOS, Ext
SOT23-5, MLP-6
Yes
Single 2A
Dual Input (+ & -)
FAN3100
CMOS, TTL
SOIC-8, MLP-8
Dual Input (+ & -), Programmable CS
FAN3177
TTL
SOIC-8 No
Non-Inv, 3V3LDO
FAN3180
SOT23-5
Dual 2A
Dual Inverting
FAN3216
Dual Non-Inverting
FAN3217
Dual Inverting + Dual Enable
FAN3226
Dual Non-Inverting + Dual Enable
FAN3227
Dual Input (+ & -); Pin 3 GND
FAN3228
Dual Input (+ & -); Pin 8 GND
FAN3229
Dual 4A
FAN3213
FAN3214
FAN3223
FAN3224
FAN3225
Single 9A
Single Inverting + Enable
FAN3121
Single Non-Inverting + Enable
FAN3122
Bridge 2A
20V Bridge Driver + Dual Enables
FAN3268
30V Bridge Driver + Dual Enables
FAN3278
Jan’2011
Every current level & input config offers a choice of …
Duals may be connected in parallel
[selection table_LS drivers_ _VN.xls]

7. Thank You

8. The Right Technology for Your Success™
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