LTC3705_15 Datasheet, PDF (3/20 Pages) Linear Technology – 2-Switch Forward Controller and Gate Driver

LTC3705
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_CC = V_BOOST = 12V, GND = PGND = V_TS = 0V, T_A = 25°C, unless
otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
I_HUVLO
Hysteresis Current
V_UVLOOP
Voltage Feedforward Operating Range
Gate Drivers (TG and BG)
V_UVLO = 1V
Primary-Side Control
● 4.2
4.9
5.6
µA
V_UVLOF(MIN)
3.75
V
R_OS
V_OH
I_PU
t_r
t_f
Rectifier
Output Pull-Down Resistance
High Output Voltage
Peak Pull-Up Current
Output Rise Time
Output Fall Time
I_OUT = 100mA
I_OUT = –100mA
10% to 90%, C_OUT = 4.7nF
10% to 90%, C_OUT = 4.7nF
1.9
Ω
11
V
1.7
A
40
ns
70
ns
I_RECT
Oscillator
Maximum Rectifier DC Output Current
25
mA
f_OSC(P)
Oscillator Frequency
∆f_RFS(P)
Oscillator Resistor Set Accuracy
f_OSC(S)
Oscillator Frequency
Soft-Start/Fault (SSFLT)
Primary-Side Control, R_FS(P) = 100kΩ
Primary-Side Control, R_FS(P) = 25kΩ
Primary-Side Control, R_FS(P) = 300kΩ
Primary-Side Control
25k < R_FSET < 300k
Secondary-Side Control (During Start-Up),
R_FS(S) = 100kΩ
200
kHz
700
kHz
70
kHz
±15
%
300
kHz
I_SS(C)
Soft-Start Charge Current
V_LRTO
Linear Regulator Time Out-Threshold
V_FLTH
Fault Output High
I_SS(D)
Soft-Start Discharge Current
Current Sense Input (I_S)
V_IS(MAX)
Overcurrent Threshold
Volt Second Limit (V_SLMT)
V_VSL(MAX) Volt-Second Limit Threshold
I_VSLMT(MAX) Maximum Volt-Second Limit Resistor Current
Optoisolator Bias Current
Primary-Side Control, V_SSFLT = 2V
Secondary-Side Control, V_UVLO = 1.3V,
V_SSFLT = 2V
Secondary-Side Control, V_UVLO = 3.75V,
V_SSFLT = 2V
V_CC = 8V
Timing Out After Fault, V_SSFLT = 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
V_OPTO
I_OPTO
Open Circuit Optoisolator Voltage
Optoisolator Bias Current
Primary-Side Control I_FB = 0V
Primary-Side Control V_FB = 2.5V
Primary-Side Control V_FB = 0V
3.3
V
0.5
mA
1.6
mA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Operating junction temperature T_J (in °C) is calculated from the
ambient temperature T_A and the average power dissipation PD (in watts)
by the formula: T_J = T_A + θ_JA • PD. Refer to the Applications Information
section for details.
Note 3: I_CC is the sum of current into NDRV and V_CC.
Note 4: The LTC3705EGN is guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3705IGN is
guaranteed and tested over the – 40°C to 85°C operating temperature
range.
3705fb
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