LT1767EMS8-18 Datasheet, PDF (3/16 Pages) Linear Technology – Monolithic 1.5A, 1.25MHz Step-Down Switching Regulators

LT1767/LT1767-1.8/
LT1767-2.5/LT1767-3.3/LT1767-5
ELECTRICAL CHARACTERISTICS
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T_A = 25°C.
V_IN = 15V, V_C = 0.8V, Boost = V_IN + 5V, SHDN, SYNC and switch open unless otherwise noted.
PARAMETER
CONDITION
MIN TYP MAX UNITS
FB Input Resistance
LT1767-1.8
LT1767-2.5
LT1767-3.3
LT1767-5
q 10.5
15
21
kΩ
q 14.7
21
30
kΩ
q 19
27.5
39
kΩ
q 29
42
60
kΩ
Error Amp Voltage Gain
Error Amp Transconductance
V_C Pin Source Current
V_C Pin Sink Current
V_C Pin to Switch Current Transconductance
V_C Pin Minimum Switching Threshold
V_C Pin 1.5A I_SW Threshold
Maximum Switch Duty Cycle
0.4V < V_C < 0.9V
∆I_VC = ±10µA
V_FB = V_NOM – 17%
V_FB = V_NOM + 17%
Duty Cycle = 0%
V_C = 1.2V, I_SW = 400mA
150
q 500
q 80
q 70
85
q 80
350
850 1300 µMho
120 160
µA
110 180
µA
2.5
A/V
0.35
V
0.9
V
90
%
%
Minimum Boost Voltage Above Switch
I_SW = –1.5A, 0°C ≤ T_A ≤ 125°C and –1.3A, T_A < 0°C
q
1.8
2.7
V
Boost Current
I_SW = – 0.5A (Note 4)
q
I_SW = –1.5A, 0°C ≤ T_A ≤ 125°C and –1.3A, T_A < 0°C (Note 4) q
10
15
mA
30
45
mA
SHDN Threshold Voltage
q 1.27 1.33 1.40
V
SHDN Input Current (Shutting Down)
SHDN = 60mV Above Threshold
q –7
–10 –13
µA
SHDN Threshold Current Hysteresis
SHDN = 100mV Below Threshold
q4
7
10
µA
SYNC Threshold Voltage
1.5
2.2
V
SYNC Input Frequency
1.5
2
MHz
SYNC Pin Resistance
I_SYNC = 1mA
20
kΩ
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1767E is guaranteed to meet performance specifications
from 0°C to 125°C. Specifications over the – 40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3: Minimum input voltage is defined as the voltage where the internal
regulator enters lockout. Actual minimum input voltage to maintain a
regulated output will depend on output voltage and load current. See
Applications Information.
Note 4: Current flows into the BOOST pin only during the on period of the
switch cycle.
TYPICAL PERFORMANCE CHARACTERISTICS
FB vs Temperature (Adj)
1.22
1.21
1.20
1.19
1.18
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
1767 G01
Switch On Voltage Drop
400
125°C
350
300
25°C
250
–40°C
200
150
100
50
0
0
0.5
1
1.5
SWITCH CURRENT (A)
1767 G02
Oscillator Frequency
1.50
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
1767 G03
sn1767 1767fas
3