AAT1160 Datasheet, PDF (11/14 Pages) Advanced Analog Technology, Inc. – Step Up Current Mode PWM Converter with 4+1 Operational Amplifiers

Advanced Analog Technology, Inc.
0.04*1.25V, or 50mV. Error amplifier output
drives 50mV*105µs, or 6.25µA, across R _C to
provide transient gain. Since the current-sense
transresistance is 0.275V/A, the value of R _C that
would allow the required load-step swing is as
follows:
R _C =0.275I_IND(PK)/6.25µA
AAT1160
In a step-up DC-to-DC converter, if L_IDEAL is used,
output current would relate to inductor current as:
I_IND(PK)=1.25I_OUT/(1-D)=1.25I_OUT* V_O / V_IN
Therefore, for a 500mA output load step with
V_IN =2.5V and V_O =5V:
R _C =[1.25(0.75*0.5*5)/2)]/6.25µA=18.7kΩ
BLOCK DIAGRAM
EO
Error amplifier
IN1
Bandgap &
1.0v _{soft start}
1.24v
SHDN
Thermal SHDN
1.0v _{Fault Detect}
Comparator
Control
Logic
Driver
FREQ
CIN+
oscillator
5u
Slope compensation ∑ current sense
Clock
Com
GND
GI1
V_DD1
Gamma1
GI2
Gamma2
GI3
Gamma3
GI4
Gamma4
V_DD
SHDN
SW
GND1
V_DD1
COUT
GO1
GO2
GO3
GO4
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– Advanced Analog Technology, Inc. –
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