LT1166 Datasheet, PDF (1/16 Pages) Linear Technology – Power Output Stage Automatic Bias System

LT1166
Power Output Stage
Automatic Bias System
FEATURES
s _{Set Class AB Bias Currents}
s _{Eliminates Adjustments}
s _{Eliminates Thermal Runaway of IQ}
s _{Corrects for Device Mismatch}
s _{Simplifies Heat Sinking}
s _{Programmable Current Limit}
s _{May Be Paralleled for Higher Current}
s _{Small SO-8 or PDIP Package}
U
APPLICATIONS
s _{Biasing Power MOSFETs}
s _{High Voltage Amplifiers}
s _{Shaker Table Amplifiers}
s _{Audio Power Amplifiers}
DESCRIPTION
The LT^®1166 is a bias generating system for controlling
class AB output current in high powered amplifiers. When
connected with external transistors, the circuit becomes a
unity-gain voltage follower. The LT1166 is ideally suited
for driving power MOSFET devices because it eliminates
all quiescent current adjustments and critical transistor
matching. Multiple output stages using the LT1166 can be
paralleled to obtain higher output current.
Thermal runaway of the quiescent point is eliminated
because the bias system senses the current in each power
transistor by using a small external sense resistor. A high
speed regulator loop controls the amount of drive applied
to each power device. The LT1166 can be biased from a pair
of resistors or current sources and because it operates on the
drive voltage to the output transistors, it operates on any
supply voltage.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
MPS2907
R1
100Ω
47Ω
2N2907
1 I_TOP = 15mA
5.6k
V_TOP
SENSE⁺
8
I_LIM+ ⁷
4.3k
V_IN
2 _{VIN LT1166 VOUT} ³
I_LIM–
SENSE^–
6
5
V_BOTTOM
4 I_BOTTOM = 15mA
15V
R2
100Ω
300pF
1k
1µF
1µF
1k
R3
100Ω
MPS2222
R4
100Ω
2N2222
47Ω
300pF
–15V
IRF530
220µF
R_SENSE+
0.33Ω
R_SENSE–
0.33Ω
V_OUT
1Ω
IRF9530
220µF
1166 • F01
INPUT
OUTPUT
Figure 1. Unity Gain Buffer with Current Limit
Unity Gain Buffer Amp Driving 1Ω Load
0V
0V
1166 • TA01
1