ml4890 ETC-unknow, ml4890 Datasheet

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ml4890

Manufacturer Part Number
ml4890
Description
High Efficiency, Low Ripple Boost Regulator
Manufacturer
ETC-unknow
Datasheet

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Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ml4890-T
Manufacturer:
MICROLINEAR
Quantity:
20 000
Part Number:
ml4890CS-5
Manufacturer:
ML
Quantity:
20 000
GENERAL DESCRIPTION
The ML4890 is a high efficiency, PFM (Pulse Frequency
Modulation), boost switching regulator connected in
series with an integrated LDO (Low Dropout Regulator)
that incorporates “Silent Switcher™” technology. This
technique incorporates a patented tracking scheme to
minimize the voltage drop across the LDO and increase
the total efficiency of the regulator beyond that which can
be obtained by using a discrete external LDO regulator.
The ML4890 is designed to convert single or multiple cell
battery inputs to regulated output voltages for integrated
circuits and is ideal for portable communications
equipment that cannot tolerate the output voltage ripple
normally associated with switching regulators.
An integrated synchronous rectifier eliminates the need for
an external Schottky diode and provides a lower forward
voltage drop, resulting in higher conversion efficiency.
BLOCK DIAGRAM
Patent Pending
*Optional
*C
IN
V
MANAGEMENT
BAT
POWER
FROM
High Efficiency, Low Ripple Boost Regulator
7
2
SHDN
V
REF
CONTROL
V
BOOST
3
IN
GND
1
L1
FEATURES
V
FEEDBACK
Incorporates “Silent Switcher™” technology to deliver
very low output voltage ripple (typically 5mV)
Guaranteed full load start-up and operation at 1.0V
input and low operating quiescent current (<100 A)
for extended battery life
Pulse Frequency Modulation and internal synchronous
rectification for high efficiency
Minimum external components
Low ON resistance internal switching MOSFETs
5V, 3.3V, and 3V output versions
L
6
5
V
BOOST
CONTROL
LDO
GND
PWR
V
OUT
4
8
C2
C1
ML4890
V
OUT
+
April 1997
1

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ml4890 Summary of contents

Page 1

... LDO and increase the total efficiency of the regulator beyond that which can be obtained by using a discrete external LDO regulator. The ML4890 is designed to convert single or multiple cell battery inputs to regulated output voltages for integrated circuits and is ideal for portable communications equipment that cannot tolerate the output voltage ripple normally associated with switching regulators ...

Page 2

... PIN DESCRIPTION PIN NO. NAME FUNCTION 1 V Battery input voltage 200mV reference output REF 3 GND Analog signal ground 4 V LDO linear regulator output OUT 2 ML4890-5/-3/-T 8-Pin SOIC (S08) V PWR GND SHDN 2 7 REF GND OUT ...

Page 3

... Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case conditions. Storage Temperature Range .................... – +150 C Lead Temperature (Soldering 10s) .......................... +260 C Thermal Resistance ( Plastic SOIC .................................................... 110 C/W OPERATING CONDITIONS Temperature Range ML4890CS-X ............................................ +70 C +0.3V BOOST ML4890ES-X ......................................... – + Operating Range IN ML4890CS-X ...

Page 4

... ML4890 V IN 100 ONE SHOT S Figure 2. PFM Regulator and LDO Block Diagram (Sumida CD54) ML4890 V PWR GND IN V SHDN REF 1 F GND OUT BOOST I OUT V OUT 100 F Figure 1. Application Test Circuit – Q1 – ...

Page 5

... It also allows the LDO to provide the maximum ripple rejection over the operating frequency range of the regulator. A block diagram of the ML4890 is shown in Figure 2. The PFM stage is comprised of Q1, Q2, A1, A2, the one shot, the flip-flop, and externals L1 and C2. The LDO stage is comprised of Q3, A3, R1, R2, the offset voltage control, and external C1 ...

Page 6

... I OUT MAX ( ) ML4890-5 200 180 160 140 120 100 1.0 1.5 2.0 2.5 3.0 3.5 V (V) IN Figure 5. Output Current versus Input Voltage. is the dropout voltage OUT(MAX) ML4890-3 100 1.0 1.5 2.0 2.5 V (V) IN 4.0 4.5 taken 3.0 ...

Page 7

... Many use a conservative current level, where inductance has dropped to 90% of its normal level. In any case good idea to try inductors of various current ratings with the ML4890 to determine which inductor is the best choice. Check efficiency and maximum output current, and if a current probe is available, look at the inductor current to see if it looks like the waveform shown in Figure 4 ...

Page 8

... F and 100 F. This provides the benefits of preventing input ripple from affecting the ML4890 control circuitry, and it also improves efficiency by reducing I-squared R losses during the charge and discharge cycles of the inductor. Again, a low ESR capacitor (such as tantalum) is recommended ...

Page 9

... Keep components as close as possible to the ML4890 • Use short trace lengths from the inductor to the V and from the output capacitor to the V • Use a single point ground for the ML4890 ground pins, and the input and output capacitors A sample PC board layout is shown in Figure 7. ...

Page 10

... ML4890 TABLE 1. MAXIMUM OUTPUT CURRENT AND EFFICIENCY ML4890 (mA) EFFICIENCY PERCENTAGE IN OUT 1.0 30.6 1.5 70.7 2.0 80 1.0 23.8 1.5 56.5 2.0 80.0 2.5 80.0 2.8 80 1.0 18.4 1.5 44.2 2.0 76.6 2.5 80.0 2.8 80 1.0 13.0 1.5 32.4 2.0 56.6 2.5 80.0 2.8 80 1.0 9.8 1.5 23.3 2.0 41.1 2.5 62.9 2.8 77 1.0 7.9 1.5 18.8 2.0 33.4 2.5 51.0 2.8 64.3 10 ML4890 73.5 1.0 72.0 1.5 70.3 2 78.7 1.0 77.3 1.5 74.9 2.0 74.0 2.5 73.7 3 82.0 1.0 81.1 1.5 77.9 2.0 76.9 2.5 76.7 3 85.7 1.0 85.1 1.5 82.7 2.0 80.4 2.5 80.1 3 87.4 1.0 87.2 1.5 85.8 2.0 83.7 2.5 82.6 3 88.4 1.0 88.9 1.5 87.6 2.0 86.0 2.5 84.6 3.0 I (mA) EFFICIENCY PERCENTAGE OUT 29.6 73.8 71.4 73.7 100.0 71.9 23.0 80.4 54.7 78.8 89.8 76.1 100.0 74.7 100.0 74.1 16.2 82.1 41.4 82.6 75.6 80.5 100.0 77.7 100.0 77 ...

Page 11

... TABLE 1. MAXIMUM OUTPUT CURRENT AND EFFICIENCY ML4890 (mA) EFFICIENCY PERCENTAGE IN OUT 1.0 13.6 1.5 42.7 2.0 82 1.0 9.3 1.5 31.7 2.0 60.6 2.5 95.7 3.0 137 1.0 7.4 1.5 23.1 2.0 46.1 2.5 73.9 3.0 108.9 3.5 145.1 4.0 184.5 4.5 200 1.0 6.0 1.5 18.3 2.0 34.2 2.5 57.0 3.0 82.3 3.5 106.0 4.0 137.1 4.5 169 1.0 1.5 14.2 2.0 25.7 2.5 41.4 3.0 59.4 3.5 82.9 4.0 105.5 4.5 131 1.0 1.5 2.0 17.9 2.5 31.7 3.0 46.2 3.5 63.2 4.0 82.5 4.5 99.7 67.9 77.2 78.1 69.6 80.9 81.6 80.5 79.4 73.6 83.6 84.6 84.0 83.0 82.4 81.3 80.1 76.9 85.8 86.8 86.6 86.2 85.3 84.6 84.0 87.2 88.3 88.3 88.0 87.3 86.6 86.2 88.9 89.8 89.7 89.6 89.2 88.0 ML4890 (continued) 11 ...

Page 12

... OUTPUT VOLTAGE ML4890CS-T ML4890CS-3 ML4890CS-5 ML4890ES-T ML4890ES-3 ML4890ES-5 © Micro Linear 1997 is a registered trademark of Micro Linear Corporation Products described in this document may be covered by one or more of the following patents, U.S.: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; Japan: 2598946; 2619299. Other patents are pending. ...

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