MIC4827BMM Micrel Inc, MIC4827BMM Datasheet - Page 7

• Manufacturer Part Number: MIC4827BMM
• Description: IC EL DRIVER 180VPP OUT 8-MSOP
• Manufacturer: Micrel Inc
• Type: EL Lamp Driverr

Specifications of MIC4827BMM

• Frequency: 60 ~ 1000 Hz
• Current - Supply: 21µA
• Voltage - Supply: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Supply Current: 21µA
• Meter Display Type: Electroluminescent Lamp
• Supply Voltage Range: 1.8V To 5.5V
• Driver Case Style: MSOP
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Output: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant, Contains lead / RoHS non-compliant

Block Diagram
Functional Description
Overview
The MIC4827 is a high-voltage EL driver with an AC
output voltage of 180V peak-to-peak capable of driving
EL lamps up to 6in
MIC4827 is typically 21µA with a typical shutdown
current of 10nA. The high voltage EL driver has two
internal oscillators to control the switching MOSFET and
the H-bridge driver. Both of the internal oscillators’
frequencies can be individually programmed through the
external resistors to maximize the efficiency and the
brightness of the lamps.
Regulation
Referring to Figure 1, initially power is applied to V
The internal feedback voltage is less than the reference
voltage causing the internal comparator to go low which
enables the switching MOSFET’s oscillator. When the
switching MOSFET turns on, current flows through the
Micrel, Inc.
July 2009
V
IN
C
IN
2
R
. Input supply current for the
EL
R
RSW
REL
SW
2
3
Oscillator
Switch
1
V
DD
Figure 1. MIC4827 Block Diagram
V
REF
DD
.
4
GND
7
inductor and into the switch. The switching MOSFET will
typically turn on for 90% of the switching frequency.
During the on-time, energy is stored in the inductor.
When the switching MOSFET turns off, current flowing
into the inductor forces the voltage across the inductor to
reverse polarity. The voltage across the inductor rises
until the external diode conducts and clamps the voltage
at V
discharged into the C
comparator continues to turn the switching MOSFET on
and off until the internal feedback voltage is above the
reference voltage. Once the internal feedback voltage is
above the reference voltage, the internal comparator
turns off the switching MOSFET’s oscillator.
When the EL oscillator is enabled, V
opposite states to achieve a 180V peak-to-peak AC
output signal. The external resistor that connects to the
REL pin determines the EL frequency.
220µH
Oscillator
L1
EL
OUT
/Q
/Q
Q
Q
+ V
1
2
3
4
D1
. The energy in the inductor is then
5
6
8
7
SW
CS
VA
VB
OUT
D1
capacitor. The internal
EL LAMP
A
and V
M9999-070709-A
C
OUT
[phone]
B
MIC4827
switch in