the charge-current amplifier transconductance = 1µA/mV.

3.3A/V. The CCS loop is a single-pole system with a dom-

The loop transfer function is given by:

Since:

Then, the loop transfer function simplifies to:

The crossover frequency is given by:

The CCS loop dominant compensation pole:

10M

Ω.

GMS = 1µA/mV

Ω

f = 400kHz

f

RC

PCS

OGMS

CS

_

=

×

1

2

π

f

GMS

C

CO CS

CS

_

=

2

π

LTF

GMS

R

sR

C

OGMS

OGMS

CS

=×

+×

1

GM

ARS

IN

CSS

=

×

1

1

LTF

GM

A

RS

GMS

R

sR

C

IN

CSS

OGMS

OGMS

CS

=×

×

×

×

+×

1

1

f

RC

PCS

OGMS

CS

_

=

×

1

2

π

Low-Cost Multichemistry Battery Chargers

______________________________________________________________________________________

23

CCS

GMS

CLS

CSSP

CSSN

CSS

RS1

Figure 9. CCS Loop Diagram

CCS LOOP GAIN

vs. FREQUENCY

FREQUENCY (Hz)

100k

10k

110

100

1k

-40

-20

0

20

40

60

80

100

-60

0.1

1M

CCS LOOP PHASE

vs. FREQUENCY

FREQUENCY (Hz)

100k

10k

1k

100

10

1

-90

-75

-60

-45

-30

-15

0

-105

0.1

1M

Figure 10. CCS Loop Gain/Phase vs. Frequency