MIC4826YMM TR Micrel Inc, MIC4826YMM TR Datasheet - Page 6

• Manufacturer Part Number: MIC4826YMM TR
• Description: IC DRIVER EL DC-AC 160VPP 8MSOP
• Manufacturer: Micrel Inc
• Type: EL Lamp Driverr

Specifications of MIC4826YMM TR

• 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,
• Driver Type: EL Lamp
• Operating Supply Voltage (typ): 1.8/2.5/3.3/5V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Package Type: MSOP
• Pin Count: 8
• Mounting: Surface Mount
• Operating Supply Voltage (min): 1.8V
• Operating Supply Voltage (max): 5.5V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / Rohs Status: Compliant
• Other names: 576-1226-2

Functional Diagram
Functional Description
See “Application Information” for component selection and
pre-designed circuits.
Overview
The MIC4826 is a high voltage EL driver with an AC output
voltage of 160V peak-to-peak capable of driving EL lamps
up to 6 in
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 oscil-
lators’ 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
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 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 induc-
tor to reverse polarity. The voltage across the inductor rises
until the external diode conducts and clamps the voltage at
V
into the C
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.
MIC4826
OUT
+V
D1
2
OUT
. Input supply current for the MIC4826 is typically
. The energy in the inductor is then discharged
V
capacitor. The internal comparator continues
IN
C
IN
R
EL
R
RWS
REL
SW
2
3
Oscillator
Switch
1
V
DD
Figure 1. MIC4826 Block Diagram
DD
V
REF
. The
4
6
GND
When the EL oscillator is enabled, V
posite states to achieve a 160V peak-to-peak AC output
signal. The external resistor that connects to the REL pin
determines the EL frequency.
Switching Frequency
The switching frequency of the converter is controlled via
an external resistor between RSW pin and VDD pin of the
device. The switching frequency increases as the resistor
value decreases. For resistor value selections, see “Typical
Characteristics: Switching Frequency vs. Switch Resistor”
or use the equation below. The switching frequency range
is 8kHz to 200kHz, with an accuracy of ±20%.
220µH
Oscillator
L1
EL
f
SW
Figure 2. 108Hz Typical Output Waveform
(
kHz
Q
Q
Q
Q
1
2
3
4
)
=
R
SW
36
(
M
TIME (2ms/div)
Ω
5
6
8
7
SW
CS
VA
VB
)
D1
A
EL LAMP
and V
C
OUT
B
switch in op-
March 2009
V
L = 220µH
C
Lamp = 2in
R
R
IN
OUT
SW
EL
= 3.0V
= 3.32M
= 332k
= 0.01µF
2