Datasheet
Table Of Contents
- Figure 1. Typical application circuit
- 1 Pin settings
- 2 Maximum ratings
- 3 Electrical characteristics
- 4 Functional description
- 5 Application notes - buck conversion
- 5.1 Closing the loop
- 5.2 GCO(s) control to output transfer function
- 5.3 Error amplifier compensation network
- 5.4 LED small signal model
- 5.5 Total loop gain
- 5.6 Compensation network design
- 5.7 Example of system design
- 5.8 Dimming operation
- 5.9 Component selection
- 5.10 Layout considerations
- 5.11 Thermal considerations
- 5.12 Short-circuit protection
- 5.13 Application circuit
- 6 Application notes - alternative topologies
- 7 Package mechanical data
- 8 Ordering information
- 9 Revision history
LED5000 Functional description
Doc ID 023951 Rev 1 11/51
4.1 Power supply and voltage reference
The internal regulator circuit consists of a startup circuit, an internal voltage pre-regulator,
the bandgap voltage reference and the bias block that provides current to all the blocks. The
starter supplies the startup current to the entire device when the input voltage goes high and
the device is enabled (inhibit pin connected to ground). The pre-regulator block supplies the
bandgap cell with a pre-regulated voltage that has a very low supply voltage noise
sensitivity.
4.2 Voltage monitor
An internal block continuously senses the V
cc
, V
ref
and V
bg
. If the monitored voltages are
good, the regulator begins operating. There is also a hysteresis on the V
cc
(UVLO).
Figure 4. Internal circuit
4.3 Soft-start
The startup phase is implemented ramping the reference of the embedded error amplifier in
1 msec typ. time. It minimizes the inrush current and decreases the stress of the power
components at power up.
Figure 5. Soft-start open
AM13488v1
AM13489v1