LTC3725 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC3725' PDF : 20 Pages View PDF
LTC3725
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 12V, GND = PGND = 0V, TA = 25°C, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Undervoltage Lockout (UVLO)
VUVLOR
Undervoltage Lockout Threshold Rising
VUVLOF
Undervoltage Lockout Threshold Falling
IHUVLO
Hysteresis Current
VUVLOOP
Voltage Feedforward Operating Range
Gate Driver (GATE)
Rising
Falling
VUVLO = 1V
Primary-Side Control
● 1.220 1.242 1.280
V
● 1.205 1.226 1.265
V
● 4.2
4.9
5.6
µA
VUVLOF(MIN)
3.75
V
ROS
VOH
IPU
tr
tf
Rectifier
Output Pull-Down Resistance
High Output Voltage
Peak Pull-Up Current
Output Rise Time
Output Fall Time
IOUT = 100mA
IOUT = –100mA
10% to 90%, COUT = 4.7nF
10% to 90%, COUT = 4.7nF
1.9
Ω
11
V
1.7
A
40
ns
70
ns
IRECT
Oscillator
Maximum Rectifier DC Output Current
25
mA
fOSC(P)
Oscillator Frequency
∆fRFS(P)
Oscillator Resistor Set Accuracy
fOSC(S)
Oscillator Frequency
Soft-Start/Fault (SSFLT)
Primary-Side Control, RFS(P) = 100kΩ
Primary-Side Control, RFS(P) = 25kΩ
Primary-Side Control, RFS(P) = 300kΩ
Primary-Side Control
25k < RFSET < 300k
Secondary-Side Control (During Start-Up),
RFS(S) = 100kΩ
200
kHz
700
kHz
70
kHz
±15
%
300
kHz
ISS(C)
Soft-Start Charge Current
VLRTO
Linear Regulator Time Out-Threshold
VFLTH
Fault Output High
ISS(D)
Soft-Start Discharge Current
Current Sense Input (IS)
VIS(MAX)
Overcurrent Threshold
Volt Second Limit (VSLMT)
VVSL(MAX) Volt-Second Limit Threshold
IVSLMT(MAX) Maximum Volt-Second Limit Resistor Current
Optoisolator Bias Current
Primary-Side Control, VSSFLT = 2V
Secondary-Side Control, VUVLO = 1.3V,
VSSFLT = 2V
Secondary-Side Control, VUVLO = 3.75V,
VSSFLT = 2V
VCC = 8V
Timing Out After Fault, VSSFLT = 2V
– 5.2
µA
–4
µA
– 1.6
µA
3.9
V
6.7
V
1
µA
300
mV
1.26
V
0.25
mA
VOPTO
IOPTO
Open Circuit Optoisolator Voltage
Optoisolator Bias Current
Primary-Side Control IFB = 0V
Primary-Side Control VFB = 2.5V
Primary-Side Control VFB = 0V
3.3
V
0.5
mA
1.6
mA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Operating junction temperature TJ (in °C) is calculated from the
ambient temperature TA and the average power dissipation PD (in watts)
by the formula: TJ = TA + θJA • PD. Refer to the Applications Information
section for details.
Note 3: ICC is the sum of current into NDRV and VCC.
3725f
3
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