6.9 Electrical Characteristics: All Output Voltage Versions (4)
Specifications with standard type face are for TJ = 25°C, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 5V.
| PARAMETER |
TEST CONDITIONS |
TYP |
MIN |
MAX |
UNIT |
| IS |
Input Supply Current |
(Switch Off)
See(7) |
11 |
|
15.5/16.5 |
mA |
| ISWITCH = 3.0A |
85 |
|
140/165 |
mA |
| VUV |
Input Supply
Undervoltage Lockout |
RLOAD = 100Ω |
3.30 |
3.05 |
3.75 |
V |
| fO |
Oscillator Frequency |
Measured at Switch Pin
RLOAD = 100Ω
VCOMP = 1.0V |
100 |
85/75 |
115/125 |
kHz |
| fSC |
Short-Circuit
Frequency |
Measured at Switch Pin
RLOAD = 100Ω
VFEEDBACK = 1.15V |
25 |
|
|
kHz |
| VEAO |
Error Amplifier
Output Swing |
Upper Limit
See(6) |
2.8 |
2.6/2.4 |
|
V |
Lower Limit
See(7) |
0.25 |
|
0.40/0.55 |
V |
| IEAO |
Error Amp
Output Current
(Source or Sink) |
See(8) |
165 |
110/70 |
260/320 |
μA |
| ISS |
Soft Start Current |
VFEEDBACK = 0.92V
VCOMP = 1.0V |
11.0 |
8.0/7.0 |
17.0/19.0 |
μA |
| D |
Maximum Duty Cycle |
RLOAD = 100Ω
See(6) |
98 |
93/90 |
|
% |
| IL |
Switch Leakage
Current |
Switch Off
VSWITCH = 60V |
15 |
|
300/600 |
μA |
| VSUS |
Switch Sustaining
Voltage |
dV/dT = 1.5V/ns |
|
65 |
|
V |
| VSAT |
Switch Saturation
Voltage |
ISWITCH = 5.0A |
0.7 |
|
1.1/1.4 |
V |
| ICL |
NPN Switch
Current Limit |
|
6.5 |
5.0 |
9.5 |
A |
(1) Note that switch current and output current are not identical in a step-up regulator. Output current cannot be internally limited when the LM2587 is used as a step-up regulator. To prevent damage to the switch, the output current must be externally limited to 5A. However, output current is internally limited when the LM2587 is used as a flyback regulator (see the section for more information).
(2) The junction temperature of the device (TJ) is a function of the ambient temperature (TA), the junction-to-ambient thermal resistance (θJA), and the power dissipation of the device (PD). A thermal shutdown will occur if the temperature exceeds the maximum junction temperature of the device: PD × θJA + TA(MAX) ≥ TJ(MAX). For a safe thermal design, check that the maximum power dissipated by the device is less than: PD ≤ [TJ(MAX) − TA(MAX))]/θJA. When calculating the maximum allowable power dissipation, derate the maximum junction temperature—this ensures a margin of safety in the thermal design.
(3) External components such as the diode, inductor, input and output capacitors can affect switching regulator performance. When the LM2587 is used as shown in
Figure 61 and
Figure 62, system performance will be as specified by the system parameters.
(4) All room temperature limits are 100% production tested, and all limits at temperature extremes are specified via correlation using standard Statistical Quality Control (SQC) methods.
(5) A 1-MΩ resistor is connected to the compensation pin (which is the error amplifier output) to ensure accuracy in measuring AVOL.
(6) To measure this parameter, the feedback voltage is set to a low value, depending on the output version of the device, to force the error amplifier output high. Adj: VFB = 1.05 V; 3.3 V: VFB = 2.81 V; 5 V: VFB = 4.25 V; 12 V: VFB = 10.2 V.
(7) To measure this parameter, the feedback voltage is set to a high value, depending on the output version of the device, to force the error amplifier output low. Adj: VFB = 1.41 V; 3.3 V: VFB = 3.8 V; 5 V: VFB = 5.75 V; 12 V: VFB = 13.8 V.
(8) To measure the worst-case error amplifier output current, the LM2587 is tested with the feedback voltage set to its low value (specified in Note 7) and at its high value (specified in Note 8).