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RC5054A
PRODUCT SPECIFICATION
4
P
Electrical Specifications
Functional Description
Initialization
The RC5054A automatically initializes upon receipt of
power. Special sequencing of the input supplies is not neces-
sary. The Power-On Reset (POR) function continually moni-
tors the input supply voltages. The POR monitors the bias
volt-age at the V
CC
pin and the input voltage (V
IN
) on the
OCSET pin. The level on OCSET is equal to V
IN
less a fixed
voltage drop (see over-current protection). The POR function
initiates soft start operation after both input supply voltages
exceed their POR thresholds. For operation with a single
+12V power source, V
IN
and V
CC
are equivalent and the
+12V power source must exceed the rising V
CC
threshold
before POR initiates operation.
Soft Start
The POR function initiates the soft start sequence. An inter-
nal 10
m
A current source charges an external capacitor (C
SS
)
on the SS pin to 4V. Soft start clamps the error amplifier out-
put (COMP pin) and reference input (+ terminal of error
amp) to the SS pin voltage. Figure 1 shows the soft start
interval with C
SS
= 0.1
m
F. Initially the clamp on the error
amplifier (COMP pin) controls the converter’s output volt-
age. At t
1
in Figure 1, the SS voltage reaches the valley of
the oscillator’s triangle wave. The oscillator’s triangular
Symbol
VCC Supply Current
I
CC
Parameter
Test Conditions
Min.
Typ.
Max.
Units
Nominal Supply
Power-On Reset
Rising VCC Threshold
Falling VCC Threshold
Rising V
OCSET
Threshold
UGATE and LGATE Open
–
22
–
mA
V
OCSET
= 4.5V
V
OCSET
= 4.5V
–
–
–
10.4
–
–
V
V
V
8.8
–
1.26
Oscillator
Free Running Frequency
Total Variation
Ramp Amplitude
RT = OPEN
6K
W
< RT to GND < 200K
W
RT = Open
185
-15
–
200
–
1.9
215
+15
–
KHz
%
V
P-P
D
V
OSC
Reference and DAC
DACOUT Voltage Accuracy
Error Amplifier
DC Gain
GBW
Gain-Bandwidth Product
SR
Slew Rate
Gate Drivers
I
UGATE
Upper Gate Source
I
UGATE
Upper Gate Sink
I
LGATE
Lower Gate Source
I
LGATE
Lower Gate Sink
Protection
Over-Voltage Trip (V
SEN
/DACOUT)
I
OCSET
OCSET Current Source
I
OVP
OVP Sourcing Current
I
SS
Soft Start Current
Power Good
Upper Threshold (V
SEN
/DACOUT)
Lower Threshold (V
SEN
/DACOUT)
Hysteresis (V
SEN
/DACOUT)
V
PGOOD
PGOOD Voltage Low
-1.0
–
+1.0
%
–
–
–
88
15
6
–
–
–
dB
MHz
V/
m
s
COMP = 10pF
V
BOOT
- V
PHASE
= 12V
V
UGATE
- V
PHASE
= 1V
V
CC
= 12V, V
LGATE
= 6V
V
UGATE
- V
PHASE
= 1V
350
–
300
–
500
100
450
100
–
–
–
–
mA
mA
mA
mA
–
115
200
–
10
120
230
–
–
%
m
A
mA
m
A
V
OCSET
= 4.5V
DC
V
SEN
= 5.5V, V
OVP
= 0V
170
60
–
VSEN Rising
VSEN Falling
Upper and Lower Threshold
I
PGOOD
= -5mA
106
89
–
–
–
–
2
111
94
–
–
%
%
%
V
0.5