
UC2577-ADJ
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Device Parameters (cont.)
Switch Transconductance
Switch Leakage Current
12.5
10
A/V
μ
A
μ
A
V
V
A
°
C/W
°
C/W
μ
A
μ
A
V
SWITCH
= 65V, V
FB
= 1.5V (Switch Off)
T
J
= 25
°
C
I
SWITCH
= 2.0A, V
COMP
= 2.0V (Max Duty Cycle)
TJ= 25
°
C
V
COMP
= 2.0V
Junction to Ambient
Junction to Case
V
COMP
= 0
T
J
= 25
°
C
600
300
0.9
0.7
6.0
Switch Saturation Voltage
0.5
NPN Switch Current Limit
Thermal Resistance
3.0
4.3
65
2
25
COMP Pin Current
50
40
Unless otherwise stated, these specifications apply for T
A
=
40
°
C
to
+125
°
C, VIN =
5V, V
FB
= V
REF
, I
SWITCH
= 0, and T
A
=T
J
.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating ratings
indicate conditions during which the device is intended to be functional, but device parameter specifications may not be
guaranteed under these conditions. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: Output current cannot be internally limited when the UC2577 is used as a step-up regulator. To prevent damage to
the switch, its current must be externally limited to 6.0A. However, output current is internally limited when the UC2577 is
used as a flyback or forward converter regulator.
Note 3. External components such as the diode, inductor, input and output capacitors can affect switching regulator
performance. When the UC2577 is used as shown in the Test Circuit, system performance will be as specified by the
system parameters.
Note 4: A 1.0M
resistor is connected to the compensation pin (which is the error amplifier’s output) to ensure accuracy in
measuring A
VOL.
In actual applications, this pin’s load resistance should be
≥
10M
, resulting in A
VOL
that is typically twice
the guaranteed minimum limit.
Figure 1. Circuit Used to Specify System Parameters
UDG-94035
L = 415-0930 (AIE)
D = any manufacturer
C
OUT
= Sprague Type 673D
Electrolytic 680
μ
F, 20V
R1 = 48.7k in series with 511
(1%)
R2 = 5.62k (1%)
3
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